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Finance & Business (35)
Discount Calculator
Calculate sale prices, savings, and discount amounts.
Open ∑Tip Calculator
Calculate tips and split the bill easily.
Open ∑VAT Calculator
Add or remove VAT from any amount.
Open ∑GST Calculator
Calculate GST-inclusive and exclusive amounts.
Open ∑Sales Tax Calculator
Calculate US sales tax for any state.
Open ∑Loan EMI Calculator
Calculate monthly loan payments and total interest.
Open ∑Margin Calculator
Calculate profit margin, markup, and revenue.
Open ∑Percent Off Calculator
See how much you save on any percent-off deal.
Open ∑Triple Discount Calculator
Stack three percentage discounts in sequence.
Open ∑Stamp Duty Calculator
Estimate stamp duty on property transfers.
Open ∑Stamp Duty Calculator Australia
Estimate Australian stamp duty by state.
Open ∑Price Elasticity of Demand Calculator
Compute price elasticity of demand instantly.
Open ∑Annuity Depreciation Calculator
Depreciate assets using the annuity method.
Open ∑Car Depreciation Calculator
See how fast your car loses value each year.
Open ∑MACRS Depreciation Calculator
US tax depreciation under the MACRS system.
Open ∑Depreciation Comparison Calculator
Compare depreciation methods side by side.
Open ∑Percentage Depreciation Calculator
Depreciate assets by a fixed yearly percentage.
Open ∑Straight Line Depreciation Calculator
Straight-line depreciation with salvage value.
Open ∑Inflation Calculator
See how inflation erodes purchasing power.
Open ∑UK Inflation Calculator
Calculate the impact of UK inflation over time.
Open ∑Stock Profit Calculator
Calculate stock profit, loss, and ROI.
Open ∑WACC Calculator
Compute Weighted Average Cost of Capital.
Open ∑Debt to Asset Ratio Calculator
Calculate the debt-to-asset ratio.
Open ∑Earnings Per Share Calculator
Calculate Earnings Per Share (EPS).
Open ∑EBIT Calculator
Calculate Earnings Before Interest & Tax.
Open ∑EBITDA Calculator
Calculate EBITDA from net income and adjustments.
Open ∑Pre & Post-Money Valuation Calculator
Compute pre- and post-money startup valuation.
Open ∑Return on Assets Calculator
Calculate Return on Assets (ROA).
Open ∑ROCE Calculator
Calculate Return on Capital Employed.
Open ∑CPM Calculator
Calculate Cost Per Thousand impressions.
Open ∑CPC Calculator
Calculate cost-per-click for paid ads.
Open ∑Enterprise Value Calculator
Calculate enterprise value (EV) of a company.
Open ∑Market Capitalization Calculator
Calculate market capitalization of a stock.
Open ∑Ending Inventory Calculator
Calculate ending inventory for accounting.
Open ∑LTV Calculator
Calculate Loan-to-Value ratio.
OpenHealth & Fitness (22)
BMI Calculator
Calculate Body Mass Index with category.
Open ∑BMR Calculator
Estimate daily calorie burn at rest (BMR).
Open ∑Calorie Calculator
Daily calorie needs for any weight goal.
Open ∑Macro Calculator
Daily protein, carb, and fat targets.
Open ∑Weight Loss Calculator
Plan a calorie deficit to hit your goal weight.
Open ∑Ideal Body Weight Calculator
Estimate ideal body weight via clinical formulas.
Open ∑Lean Body Mass Calculator
Estimate lean body mass from weight and body fat.
Open ∑FFMI Calculator
Calculate Fat-Free Mass Index for lifters.
Open ∑BSA Calculator
Calculate Body Surface Area (BSA).
Open ∑BMI & BSA Calculator
Combined BMI + BSA clinical calculator.
Open ∑RMR Calculator
Calculate Resting Metabolic Rate.
Open ∑EER Calculator
Estimated Energy Requirement (IOM equation).
Open ∑McArdle BMR Calculator
BMR via the McArdle LBM-based formula.
Open ∑Meal Calorie Calculator
Split daily calories across meals.
Open ∑Army Body Fat Calculator
US Army circumference body fat formula.
Open ∑Navy Body Fat Calculator
US Navy circumference body fat method.
Open ∑Heart Rate Calculator
Target training heart rate zones.
Open ∑Maximum Heart Rate Calculator
Estimate maximum heart rate.
Open ∑Cardiovascular Risk Calculator
10-year cardiovascular risk estimate.
Open ∑ABV Calculator
Alcohol-by-volume for homebrewing.
Open ∑1RM Calculator
Estimate one-rep max from a submax set.
Open ∑Calorie Burn Calculator
Calories burned per exercise (MET).
OpenMedical Scoring (37)
Blood Type Calculator
Predict a child's blood type from parents.
Open ∑Depression Self-Test (PHQ-9)
PHQ-9 depression screening self-test.
Open ∑ANC Calculator
Absolute Neutrophil Count from WBC.
Open ∑ALC Calculator
Absolute Lymphocyte Count from WBC.
Open ∑QTc Calculator
Corrected QT interval on an ECG.
Open ∑Calcium Correction Calculator
Albumin-corrected serum calcium.
Open ∑Creatinine Clearance Calculator
Cockcroft-Gault creatinine clearance.
Open ∑Total Body Water Calculator
Total Body Water via Watson / Hume.
Open ∑Reticulocyte Count Calculator
Corrected reticulocyte count and index.
Open ∑LDL Calculator
LDL via Friedewald formula.
Open ∑Cholesterol Calculator
Cholesterol ratios for cardio risk.
Open ∑Bicarbonate Deficit Calculator
Bicarbonate deficit in metabolic acidosis.
Open ∑4AT Delirium Screening Score
4AT rapid delirium screening.
Open ∑6 Minute Walk Test Calculator
Predicted 6-minute walk distance.
Open ∑AMTS Calculator
Abbreviated Mental Test for cognition.
Open ∑ABCD2 Score for TIA
2-day stroke risk after TIA.
Open ∑ABC Score for Massive Transfusion
Predict massive transfusion in trauma.
Open ∑Acute Gout Diagnosis Calculator
Clinical prediction for acute gout.
Open ∑Adult ADHD Self-Report Scale
ASRS adult ADHD screening.
Open ∑AIMS65 Score Calculator
AIMS65 upper GI bleed mortality.
Open ∑ASPECT Score
ASPECT score for CT stroke.
Open ∑Alvarado Score for Appendicitis
Alvarado score for appendicitis.
Open ∑Asthma Control Test
5-item Asthma Control Test.
Open ∑AUDIT-C Alcohol Screening
AUDIT-C alcohol use screening.
Open ∑Bacterial Meningitis Score
Rule-out pediatric bacterial meningitis.
Open ∑BAP-65 Score for COPD
Acute COPD exacerbation mortality risk.
Open ∑Barthel Index Calculator
ADL functional status score.
Open ∑BISAP Score for Pancreatitis
Acute pancreatitis mortality score.
Open ∑Centor Score for Strep Pharyngitis
Strep pharyngitis probability.
Open ∑CHA₂DS₂-VASc Score
AFib stroke risk stratification.
Open ∑CHADS₂ Score
Legacy A-fib stroke risk score.
Open ∑Child-Pugh Score
Cirrhosis severity classification.
Open ∑CURB-65 Score
CAP severity with CURB-65.
Open ∑EGSYS Score for Syncope
Cardiac syncope prediction.
Open ∑4Ts Score for HIT
HIT pretest probability.
Open ∑Geriatric Depression Scale
15-item GDS depression screen.
Open ∑Blood Pressure Calculator
AHA-2017 BP category check.
OpenMath & Statistics (27)
Percentage Calculator
Calculate percentages, increases, decreases, and more.
Open ∑Log Calculator
Natural log, base-10, and any-base log.
Open ∑Antilog Calculator
Inverse logarithm in any base.
Open ∑Rounding Calculator
Round numbers to decimals or sig figs.
Open ∑Standard Deviation Calculator
Standard deviation, variance, and mean.
Open ∑Average Calculator
Mean, median, and mode of a list.
Open ∑Percent Error Calculator
Percent error for measurements.
Open ∑Percentage Increase Calculator
Calculate percent increase or decrease.
Open ∑Proportion Calculator
Solve a : b = c : x style proportions.
Open ∑Critical Value Calculator
Critical values for z, t, chi-sq, F.
Open ∑Margin of Error Calculator
Survey / sample margin of error.
Open ∑Poisson Distribution Calculator
Poisson PMF and CDF.
Open ∑Hypergeometric Calculator
Hypergeometric probability PMF.
Open ∑Confidence Interval Calculator
CIs for mean and proportion.
Open ∑Factorial Calculator
Compute n! for any integer n.
Open ∑Significant Figures Calculator
Round to N significant figures.
Open ∑Covariance Calculator
Covariance of two data sets.
Open ∑Modulo Calculator
Compute a mod b with big numbers.
Open ∑Remainder Calculator
Division remainder + quotient.
Open ∑Midpoint Calculator
Midpoint between two points.
Open ∑Cross Product Calculator
3D vector cross product.
Open ∑Arcsin Calculator
Inverse sine in degrees or radians.
Open ∑Arithmetic Sequence Calculator
Nth term + sum of arithmetic sequence.
Open ∑Binary Translator
Translate binary to/from text or decimal.
Open ∑Octal Calculator
Octal arithmetic in base-8.
Open ∑Hexadecimal Calculator
Add, sub, mul, div in hex.
Open ∑Binary Calculator
Base-2 addition, subtraction, multiplication, division.
OpenGeometry (17)
Slope Calculator
Slope m between two points.
Open ∑Circumference Calculator
Circle circumference.
Open ∑Circle Area Calculator
Area of a circle (πr²).
Open ∑Sector Area Calculator
Circular sector area.
Open ∑Ellipse Area Calculator
Ellipse area (πab).
Open ∑Rectangle Area Calculator
Rectangle area and perimeter.
Open ∑Parallelogram Area Calculator
Parallelogram area (b×h).
Open ∑Trapezoid Area Calculator
Trapezoid area ((a+b)/2 × h).
Open ∑Triangle Centroid Calculator
Centroid of a triangle.
Open ∑Pythagorean Theorem Calculator
Right-triangle a² + b² = c².
Open ∑Arc Length Calculator
Circle arc length.
Open ∑Cubic Meter Calculator
Cubic meters for cargo volume.
Open ∑Cylinder Volume Calculator
Cylinder volume (πr²h).
Open ∑Sphere Calculator
Sphere volume and surface area.
Open ∑Cone Volume Calculator
Cone volume ((1/3)πr²h).
Open ∑Board Foot Calculator
Lumber board-foot volume.
Open ∑Mulch Calculator
Cubic yards of mulch needed.
OpenPhysics & Engineering (5)
Everyday & Misc. (10)
GPA Calculator
Calculate your grade point average (US 4.0 scale).
Open ∑Bill Splitter
Split a bill fairly among any number of people.
Open ∑MPG Calculator
Calculate miles per gallon and fuel cost.
Open ∑Age Calculator
Calculate exact age in years, months, and days.
Open ∑Yu-Gi-Oh! Life Point Calculator
Track duel Life Points easily.
Open ∑ERA Calculator
Baseball earned run average.
Open ∑Days Between Dates Calculator
Exact days between two dates.
Open ∑Shoe Size Converter
Shoe sizes US/UK/EU/JP.
Open ∑Speed Converter
Speed conversion in any unit.
Open ∑US Tipping Guide
US tipping guide + calculator.
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