152 free evidence-based calculators across 23 medical specialties
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Calculate your Body Mass Index (BMI) instantly using height and weight. Free, WHO-validated formula with personalized health category insights for adults.
Calculate your ideal body weight using multiple formulas (Devine, Robinson, Miller, Hamwi). Find a healthy weight range based on your height and sex.
Calculate your body fat percentage using the U.S. Navy method. Enter your measurements to estimate body fat and understand your fitness category.
Calculate your waist-to-hip ratio (WHR) to assess cardiovascular disease risk. A simple measurement used by the WHO as a health indicator.
Calculate your waist-to-height ratio (WHtR) to screen for cardiometabolic risk. A simple metric where keeping your waist under half your height is often recommended.
Calculate body surface area using Du Bois, Mosteller, and Haycock formulas. Free BSA calculator for chemotherapy dosing, cardiac index, and clinical calculations. BSA depends on weight — check [BMI Calculator](/tools/bmi-calculator).
Calculate your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation. Estimate how many calories your body burns at rest each day. Multiply by activity factor with [TDEE Calculator](/tools/tdee-calculator).
Calculate your Total Daily Energy Expenditure (TDEE) instantly using the Mifflin-St Jeor equation. Free, evidence-based calorie calculator with BMR breakdown and activity adjustments.
Calculate your daily macronutrient needs for protein, carbs, and fat. Free macro calculator with customizable splits for cutting, bulking, or maintenance goals.
Calculate your recommended daily water intake based on body weight and activity level. Stay properly hydrated with personalized recommendations.
Calculate your daily calorie needs based on the Mifflin-St Jeor equation. Get personalized BMR, TDEE, and target calories for weight loss, maintenance, or gain.
Track pregnancy weight gain against IOM guidelines. Calculates recommended total gain based on pre-pregnancy BMI and current gestational age.
Calculate BMI-for-age percentile for children and teens (ages 2–20). Based on CDC growth chart data for weight classification.
Look up glycemic index values for common foods to help manage blood sugar and diet planning.
Calculate recommended daily protein intake based on body weight, activity level, and fitness goals.
Calculate estimated glomerular filtration rate (eGFR) using the CKD-EPI 2021 race-free equation. Free kidney function assessment with CKD staging from serum creatinine.
Calculate creatinine clearance (CrCl) using the Cockcroft-Gault equation. Used for renal drug dosing adjustments based on kidney function.
Calculate corrected QT interval using Bazett, Fridericia, and Framingham formulas. Assess QT prolongation risk from ECG measurements.
Estimate blood alcohol concentration (BAC) from standard drinks, body weight, sex, and time since drinking started using a Widmark-style model. Screen for alcohol use disorder with [AUDIT](/tools/audit) or [CAGE Questionnaire](/tools/cage).
Calculate the MELD and MELD-Na scores to assess liver disease severity and transplant priority. Uses bilirubin, INR, creatinine, and sodium.
Calculate the Child-Pugh score to classify the severity of chronic liver disease and estimate prognosis. Uses bilirubin, albumin, INR, ascites, and encephalopathy.
Calculate the anion gap and albumin-corrected anion gap to help evaluate metabolic acidosis. Essential for the ER and ICU workup.
Calculate the alveolar-arterial oxygen gradient to evaluate the cause of hypoxemia. Differentiates lung pathology from hypoventilation.
Calculate corrected calcium adjusted for albumin levels. Essential for accurate interpretation of total calcium in hypoalbuminemic patients.
Interpret arterial blood gas (ABG) results to identify acid-base disorders. Determines primary disorder and compensation status from pH, pCO₂, and HCO₃⁻.
Estimate PaO₂ from SpO₂ pulse oximetry using the oxygen-hemoglobin dissociation curve. SpO₂ 98%≈100 mmHg, 95%≈80, 90%≈60 (critical threshold). Useful when ABG is unavailable.
Convert laboratory values between conventional (US) and SI (international) units for 20+ common tests including creatinine, glucose, cholesterol, hemoglobin, electrolytes, and thyroid function.
Calculate corrected sodium level for hyperglycemia using the Katz formula. Essential for evaluating true sodium status in patients with elevated glucose.
Calculate Mean Arterial Pressure (MAP = DBP + ⅓ × pulse pressure). Normal MAP: 70–100 mmHg. Sepsis target: MAP ≥65 mmHg. MAP <60 mmHg indicates inadequate organ perfusion requiring immediate intervention.
Calculate expected pCO₂ for respiratory compensation in metabolic acidosis using Winter's formula: expected pCO₂ = 1.5 × [HCO₃] + 8 ± 2. Compare to actual pCO₂ to identify concurrent respiratory disorders.
Calculate serum osmolality from sodium, glucose, and BUN. Normal range: 275–295 mOsm/kg. Osmolal gap >10 suggests toxic alcohol ingestion (methanol, ethylene glycol, isopropanol) or other unmeasured osmoles.
Calculate adjusted body weight (AdjBW) for drug dosing in obese patients: AdjBW = IBW + 0.4 × (TBW − IBW). Used for aminoglycosides, vancomycin, and other weight-based medications when actual weight exceeds IBW by >20%.
Calculate corrected sodium in hyperglycemia using the Katz formula: add 1.6 mEq/L per 100 mg/dL glucose above normal. Essential in DKA to reveal true sodium status hidden by osmotic dilution from hyperglycemia.
Calculate the transtubular potassium gradient (TTKG) to evaluate renal potassium handling. TTKG >7–8 in hypokalemia suggests urinary potassium wasting; TTKG <5 in hyperkalemia indicates renal tubular dysfunction or hypoaldosteronism.
Estimate calories burned from exercise using activity MET values, body weight, and duration. Useful for fitness planning and weight-management tracking. Combine with [TDEE Calculator](/tools/tdee-calculator) for full energy balance.
Estimate ideal bedtimes or wake times based on 90-minute sleep cycles and sleep latency. Helps plan schedules around 7-9 hours of sleep. Poor sleep affects calorie balance — track with [TDEE Calculator](/tools/tdee-calculator).
Calculate your estimated one-rep max using Epley, Brzycki, and Lander formulas. Determine your maximum strength from submaximal lifts. Pair with [Heart Rate Zones Calculator](/tools/heart-rate-zones) and [VO2 Max Estimator](/tools/vo2-max-calculator) for complete fitness profiling.
Calculate your personal heart rate training zones using the Karvonen method. Optimize your cardio training with zones based on age and resting heart rate. Estimate aerobic capacity with [VO2 Max Estimator](/tools/vo2-max-calculator).
Estimate your VO2 max from resting heart rate using the Uth method. Assess your cardiorespiratory fitness level and aerobic capacity. Higher VO2 max correlates with lower cardiovascular risk — see [ASCVD Risk Calculator](/tools/ascvd-risk).
Calculate the CHA₂DS₂-VASc score to estimate stroke risk in patients with atrial fibrillation and guide anticoagulation therapy decisions.
Calculate the HAS-BLED score to assess bleeding risk in patients on anticoagulation therapy. Balance stroke prevention against bleeding risk.
Calculate your 10-year risk of cardiovascular disease using the Framingham Risk Score. Based on the landmark Framingham Heart Study data.
Calculate the HEART Score to assess the risk of major adverse cardiac events (MACE) in patients presenting with chest pain.
Classify blood pressure readings into Normal, Elevated, Stage 1, Stage 2, or Hypertensive Crisis using ACC/AHA thresholds. Includes MAP and pulse pressure.
Estimate your heart age from major cardiovascular risk factors using ASCVD-based risk modeling. Compare vascular age with chronological age.
Calculate LDL cholesterol from total cholesterol, HDL, and triglycerides using the Friedewald equation. Also reports non-HDL and total/HDL ratio.
Calculate total cholesterol/HDL ratio and triglyceride/HDL ratio from a standard lipid panel. A total/HDL ratio below 3.5 is optimal. For full cardiovascular risk assessment, use [ASCVD Risk Calculator](/tools/ascvd-risk) or [Framingham Risk Score](/tools/framingham-risk).
Classify heart failure severity using the New York Heart Association (NYHA) functional classification system. Classes I–IV based on physical activity limitations.
Calculate 10-year ASCVD risk using current 2026 ACC/AHA Pooled Cohort Equations. Statin thresholds: <5% low, 5–7.5% borderline, ≥7.5% intermediate, ≥20% high.
Calculate the Duke Treadmill Score for cardiac risk stratification from exercise stress testing. Uses exercise time, ST deviation, and angina symptoms.
Calculate the TIMI risk score for STEMI to predict 30-day mortality.
Calculate the TIMI risk score for NSTEMI and unstable angina to predict 14-day adverse cardiac events.
Calculate the GRACE score for in-hospital mortality risk in acute coronary syndrome patients.
Calculate the Wells Score to assess the clinical probability of deep vein thrombosis (DVT). Guide diagnostic workup and D-dimer testing.
Calculate the Wells Score to estimate the clinical probability of pulmonary embolism (PE). Guide decisions on CTPA and D-dimer testing.
Calculate the CURB-65 score to assess pneumonia severity and determine the need for hospitalization or ICU admission.
Calculate the Glasgow Coma Scale score to assess level of consciousness. Used worldwide in emergency medicine and trauma assessment.
Calculate the APACHE II score to predict ICU mortality risk. Uses acute physiological variables, age, and chronic health status.
Apply the PERC Rule to rule out pulmonary embolism in low-risk patients without D-dimer testing. Reduces unnecessary testing.
Calculate the Shock Index (HR/SBP ratio) for rapid hemodynamic assessment. Normal: 0.5–0.7. Score ≥1.0 indicates hemodynamic compromise; ≥1.4 indicates severe shock requiring immediate intervention.
Calculate the qSOFA score for rapid bedside sepsis screening. Score ≥2 (altered mentation, RR ≥22, SBP ≤100 mmHg) identifies patients at high risk for poor outcomes — no labs required.
Calculate the SOFA score to assess organ dysfunction severity in critically ill patients. Scores range from 0 to 24 across six organ systems.
Evaluate SIRS criteria for systemic inflammatory response. Two or more criteria (temperature, HR, RR, WBC) indicates SIRS. Note: Sepsis-3 definitions now prefer qSOFA and SOFA scoring.
Calculate IV fluid requirements for burn patients using the Parkland formula: 4 mL × kg × % TBSA in 24 hours. Half given in first 8 hours from injury, half over next 16 hours.
Calculate the Revised Trauma Score (RTS) for trauma triage and survival prediction. Combines GCS, systolic BP, and respiratory rate. Maximum score 7.84; RTS <4 predicts high mortality.
Apply the Canadian CT Head Rule to determine if CT is needed after minor head injury (GCS 13–15). Achieves 98.4% sensitivity for neurosurgically significant injuries, safely reducing CT use.
Apply the NEXUS criteria to determine if cervical spine imaging is needed after trauma. All 5 criteria absent gives 99.8% NPV for significant C-spine injury, safely avoiding CT or X-ray.
Calculate your estimated due date (EDD) from your last menstrual period using Naegele's rule. Track gestational age and trimester.
Predict your next period date using your last menstrual period and average cycle length. See cycle day, fertile window, and upcoming period dates.
Estimate your ovulation date and fertile window using cycle length and last period date. See best days to conceive and estimated due date if conception occurs.
Estimate your conception date from your last menstrual period and cycle length, or from your estimated due date. Includes likely conception window and ovulation estimate.
Calculate the Bishop Score to assess cervical favorability for labor induction. Predicts likelihood of successful vaginal delivery.
Calculate the Apgar Score to quickly assess newborn health at 1 and 5 minutes after birth. Evaluates appearance, pulse, grimace, activity, and respiration.
Calculate gestational age in weeks and days from your last menstrual period (LMP). Instantly see trimester, estimated due date, and days remaining. Free and accurate.
Calculate estimated fetal weight (EFW) using the Hadlock formula from ultrasound biometry: BPD, HC, AC, and FL. Instantly classify SGA, AGA, or LGA by gestational age.
Time contractions during labor to track duration, frequency, and pattern for the 5-1-1 rule.
Live timer for Apgar scoring at 1 and 5 minutes after birth with real-time assessment.
Calculate IV infusion rates in mL/hr and drops per minute from volume, time, and drop factor. Essential nursing and pharmacy calculator for safe, accurate IV fluid and medication administration.
Calculate morphine milligram equivalents (MME) for opioid medications using CDC conversion factors. ≥50 MME/day warrants caution; ≥90 MME/day carries significantly increased overdose risk.
Calculate pediatric medication doses based on patient weight (mg/kg). Essential for safe pediatric prescribing.
Get warfarin dose adjustment guidance based on current INR and target range. Helps manage anticoagulation therapy.
Calculate gentamicin dose and interval using extended-interval (5–7 mg/kg q24h) or traditional q8–12h dosing methods based on creatinine clearance and adjusted body weight.
Determine renal dose adjustment guidance by GFR stage for antibiotics, anticoagulants, metformin, NSAIDs, and 20+ drug classes. Based on current KDIGO CKD staging and prescribing guidelines.
Convert HbA1c to estimated average glucose (eAG): 6%=126 mg/dL, 7%=154, 8%=183, 9%=212. ADA 2026 target <7% for most adults with diabetes. Shows both mg/dL and mmol/L.
Calculate the insulin correction factor (sensitivity factor) using the 1800 and 1500 rules. Determine how much 1 unit of insulin lowers blood glucose.
Interpret TSH and free T4 to assess thyroid function. Normal TSH: 0.4–4.0 mIU/L. Identifies overt and subclinical hypothyroidism, hyperthyroidism, and euthyroid sick syndrome.
Estimate the starting levothyroxine dose for hypothyroidism: ~1.6 mcg/kg/day for full replacement, ~25–50 mcg/day for subclinical hypothyroidism. Recheck TSH at 6–8 weeks.
Convert between corticosteroid doses by anti-inflammatory potency equivalence: prednisone 5 mg = hydrocortisone 20 mg = methylprednisolone 4 mg = dexamethasone 0.75 mg.
Calculate the NIH Stroke Scale (NIHSS) to quantify stroke severity. Mild ≤4, Moderate 5–15, Severe 16–20, Very Severe >20. Guides IV tPA eligibility and acute stroke unit treatment decisions.
Calculate the ABCD² score to estimate stroke risk after TIA. Score 6–7: 8.1% two-day risk. Score 4–5: 4.1%. Score 0–3: 1.0%. Guides inpatient admission vs expedited outpatient workup.
Classify subarachnoid hemorrhage severity using the Hunt & Hess scale to predict surgical outcomes.
Classify subarachnoid hemorrhage on CT using the Fisher grading scale to predict vasospasm risk.
Free PHQ-9 depression screening questionnaire. Take the Patient Health Questionnaire-9 to assess depression severity with instant scoring and interpretation. Also screen for anxiety with [GAD-7](/tools/gad7).
Free GAD-7 anxiety screening questionnaire. Take the Generalized Anxiety Disorder 7-item scale to assess anxiety severity with instant scoring and interpretation. Also screen for depression with [PHQ-9](/tools/phq9).
Quick two-question depression screen using the PHQ-2. A score of 3 or higher suggests further evaluation with the full [PHQ-9](/tools/phq9).
Quick two-question anxiety screen using the GAD-2. A score of 3 or higher suggests further evaluation with the full [GAD-7](/tools/gad7).
Screen for hazardous and harmful alcohol use with the 10-question AUDIT. Scores range from 0 to 40 across four risk zones. For quick screening use [CAGE](/tools/cage).
Quick four-question alcohol screening using the CAGE questionnaire. A score of 2 or more suggests possible alcohol problems. For comprehensive screening, use [AUDIT](/tools/audit).
Screen for postnatal depression using the Edinburgh Postnatal Depression Scale. Scores of 10 or higher suggest possible depression.
Screen for PTSD using the PCL-5 checklist. Score ranges from 0 to 80; a score of 31-33 or higher suggests probable PTSD.
Screen for suicidal ideation and behavior using the Columbia Suicide Severity Rating Scale screener version. Assesses risk level based on ideation severity.
Interpret Montreal Cognitive Assessment (MoCA) scores. The leading cognitive screening tool for mild cognitive impairment and dementia.
Screen for depression using the WHO-endorsed Major Depression Inventory (MDI). A 10-item self-report questionnaire scoring 0–50.
Interpret Mini-Mental State Examination (MMSE) scores. The classic cognitive screening test for dementia, scoring 0–30.
Interpret Beck Depression Inventory-II (BDI-II) total scores. One of the most widely cited depression severity measures, scoring 0–63.
Calculate the Psoriasis Area and Severity Index (PASI) to assess psoriasis severity across four body regions. Scores range from 0 to 72. Pair with [DLQI Score](/tools/dlqi) for biologic eligibility assessment.
Estimate total body surface area (TBSA) affected by burns using the Rule of Nines. Enter affected areas to calculate total burn percentage. Then use TBSA result in [Parkland Formula](/tools/parkland-formula) for fluid resuscitation.
Calculate the Dermatology Life Quality Index (DLQI) to measure skin disease impact on quality of life. Score >10 indicates very large effect and is the NICE threshold for biologic therapy eligibility.
Screen a mole against the ABCDE melanoma warning signs: Asymmetry, Border irregularity, Color variation, Diameter >6mm, and Evolving changes. Any positive sign warrants urgent dermatology evaluation.
Estimate total body surface area (TBSA) burned using the Rule of Nines. Head=9%, each arm=9%, each leg=18%, torso=36%. Burns ≥20% TBSA require IV fluid resuscitation with the Parkland formula.
Assess independence in six basic activities of daily living using the Katz Index. Scores range from 0 (dependent) to 6 (fully independent). Pair with [Morse Fall Scale](/tools/morse-fall-scale) for fall risk and [Timed Up and Go](/tools/get-up-and-go) for mobility.
Assess fall risk in hospitalized patients using the Morse Fall Scale. Scores categorize patients as low, moderate, or high fall risk. Pair with [Timed Up and Go Test](/tools/get-up-and-go) for objective mobility assessment.
Assess frailty using the Rockwood Clinical Frailty Scale (CFS 1–9): Very Fit to Terminally Ill. Used for ICU triage, surgical risk stratification, and goals-of-care discussions in elderly patients.
Screen for delirium using the CAM (Confusion Assessment Method). Gold standard with ~94% sensitivity and ~89% specificity. Requires acute onset + inattention, plus disorganized thinking or altered consciousness.
Assess mobility and fall risk with the Timed Up and Go (TUG) test. TUG >12 seconds indicates high fall risk. Times the performance of standing, walking 3 meters, turning, and returning to seated.
Assess level of consciousness in infants and young children using the Pediatric Glasgow Coma Scale. Scores range from 3 to 15.
Estimate pediatric weight by age using APLS formulas (ages 1–5: 2×age+8 kg; ages 6–14: 3×age+7 kg). Critical for emergency drug dosing and equipment sizing when a scale is unavailable.
Assess neonatal jaundice severity using the Bhutani nomogram. Plots total serum bilirubin against age in hours to determine risk zone (low, low-intermediate, high-intermediate, high) and guide phototherapy decisions.
Calculate the Modified Centor (McIsaac) Score for streptococcal pharyngitis probability. Score 0–1: no testing needed. Score 2–3: rapid strep test. Score 4–5: treat empirically with antibiotics.
Estimate vancomycin AUC/MIC from dose, interval, trough level, and weight. Target AUC/MIC 400–600 for MRSA per 2020 ASHP/IDSA/SIDP guidelines. Adjust dose for renal impairment.
Convert nasal cannula flow rate (L/min) to FiO₂%. Each L/min adds ~4% above 21% room air baseline. Required input for P/F Ratio and A-a Gradient calculations in ICU and ED.
Calculate the P/F ratio to classify ARDS severity by Berlin criteria. Mild: 200–300 (27% mortality). Moderate: 100–200 (32%). Severe: <100 (45%). Normal P/F is 400–500.
Calculate O2 cylinder duration for D, E, G, H/K, and M tanks. Enter PSI and flow rate (L/min) for instant results in minutes and hours. Essential for EMS and home oxygen.
Calculate pack-years from cigarettes per day and years smoked. Useful for documenting smoking burden and lung cancer screening discussions.
Calculate the Asthma Control Test score to assess asthma control over the past 4 weeks.
Classify COPD severity using 2024 GOLD spirometric stages (GOLD 1–4) and ABE exacerbation grouping. Guides inhaler step-up therapy, pulmonary rehabilitation, and oxygen therapy decisions.
Calculate the Fractional Excretion of Sodium (FENa) to differentiate pre-renal azotemia (FENa <1%) from intrinsic renal disease such as ATN (FENa >2%) in acute kidney injury.
Calculate the BUN/Creatinine ratio to distinguish pre-renal from intrinsic acute kidney injury. Normal ratio 10–20. Ratio >20 suggests pre-renal azotemia; <10 suggests intrinsic renal disease.
Calculate free water deficit for hypernatremia using TBW × (serum Na/140 − 1). Includes safe correction rate guidance: ≤10–12 mEq/L per 24h to avoid cerebral edema.
Calculate the urine anion gap to differentiate GI from renal causes of non-anion gap metabolic acidosis. Negative UAG suggests GI bicarbonate loss; positive UAG suggests renal tubular acidosis.
Calculate measured creatinine clearance from a 24-hour urine collection. More accurate than estimated GFR in certain populations.
Use the Ottawa Ankle Rules to determine if an ankle X-ray is needed after injury. A validated clinical decision rule with ~98% sensitivity for fractures.
Apply the Ottawa Knee Rules to determine if a knee X-ray is needed after acute knee injury. ~99% sensitivity for clinically significant fractures. Reduces knee X-rays by over 25% when applied correctly.
Estimate 10-year risk of major osteoporotic and hip fracture using the WHO FRAX tool. Treatment threshold: major fracture risk ≥20% or hip fracture risk ≥3% in patients without BMD testing.
Calculate the International Prostate Symptom Score (IPSS/AUA-SI) to assess BPH symptom severity. Mild (0–7): watchful waiting. Moderate (8–19): medications. Severe (20–35): surgical evaluation.
Calculate PSA density (PSAD) to differentiate BPH from prostate cancer. PSAD ≥0.15 ng/mL/mL indicates higher cancer risk and may warrant biopsy even with borderline total PSA levels.
Estimate prostate volume from TRUS or MRI measurements using the ellipsoid formula (π/6 × L × W × H). Normal prostate is 20–30 mL; volume >40 mL suggests clinically significant BPH.
Calculate the IIEF-5 to classify erectile dysfunction severity: Severe (5–7), Moderate (8–11), Mild-Moderate (12–16), Mild (17–21), No ED (22–25). Guides PDE5 inhibitor and referral decisions.
Calculate the STONE score to predict kidney stones in ED patients with flank pain. High score ≥10: 88.6% probability. Moderate 5–9: 51.3%. Low ≤4: 9.2%. Guides CT imaging decisions.
Interpret post-void residual (PVR) volume for urinary retention and BPH evaluation. PVR <50 mL: normal. 50–200 mL: equivocal. >300 mL: significant retention requiring intervention.
Calculate PSA doubling time (PSADT) to monitor prostate cancer progression after treatment. PSADT <3 months: aggressive recurrence. 3–12 months: intermediate. >12 months: lower-risk.
Calculate the UCSF-CAPRA score for prostate cancer risk stratification. Low (0–2), Intermediate (3–5), High (6–10) risk categories guide treatment choice and predict biochemical recurrence.
Calculate the Overactive Bladder Symptom Score (OABSS) to assess OAB severity. Mild (3–5), Moderate (6–11), Severe (≥12) guides anticholinergic or beta-3 agonist therapy selection.
Estimate bladder volume from ultrasound length, width, and height measurements using the ellipsoid formula (0.523 × L × W × H). Essential for urinary retention diagnosis and BPH assessment.
Estimate kidney stone recurrence risk at 2 and 5 years using the ROKS nomogram. Considers stone composition, number of episodes, and risk factors. Guides preventive treatment intensity.
Calculate EORTC risk scores for non-muscle invasive bladder cancer recurrence and progression. Low, Intermediate, or High risk guides BCG therapy, intravesical chemotherapy, and cystoscopy frequency.
Calculate the Rockall score to predict rebleeding and mortality in upper GI hemorrhage. Pre-endoscopy score ≤2: low risk for rebleeding. Post-endoscopy score 0: <5% rebleeding risk.
Calculate the Glasgow-Blatchford score to identify low-risk upper GI bleed patients. Score 0–1: safe for outpatient endoscopy without admission. Higher scores guide urgency and ICU level of care.
Calculate the 4T score for heparin-induced thrombocytopenia (HIT) pretest probability. Score ≤3: >99% NPV for HIT. Intermediate/High (≥4): stop heparin, start alternative anticoagulation.
Calculate the Revised Geneva Score to estimate clinical probability of pulmonary embolism.