Free Online Calculators
Free calculators for math, finance, health, and everyday decisions โ with instant results, clear formulas, worked examples, and practical explanations.
Calculator categories
Start with a topic to find related tools, then move between calculators through contextual links.
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Search and browse the calculators that are currently part of the public working catalog.
Percentage Calculator
Calculate percentages instantly. Find what % of a number is, what percent one number is of another, or % change.
Percentage Increase Calculator
Percentage Increase Calculator with verified inputs, formula, and calculation logic.
Percentage Decrease Calculator
Percentage Decrease Calculator with verified inputs, formula, and calculation logic.
Average Calculator
Calculate average with explicit client-side inputs.
Square Root Calculator
Square Root Calculator with verified inputs, formula, and calculation logic.
Exponent Calculator
Calculate a number raised to a power.
Circumference Calculator
Circumference Calculator with verified inputs, formula, and calculation logic.
Slope Calculator
Calculate slope and intercept from two points.
Pythagorean Theorem Calculator
Calculate pythagorean theorem with guarded client-side formulas.
Discount Calculator
Calculate sale price and discount savings.
Sales Tax Calculator
Calculate sales tax and total purchase amount.
Margin Calculator
Calculate margin from revenue and cost.
Markup Calculator
Markup Calculator with verified inputs, formula, and calculation logic.
Simple Interest Calculator
Calculate simple interest using principal, annual rate, and years.
Compound Interest Calculator
Project compound growth with compounding frequency and recurring contributions.
BMI Calculator
Calculate your Body Mass Index (BMI) using metric or imperial units. Get your weight category and healthy weight range.
Calorie Calculator
Calculate your daily calorie needs using the Mifflin-St Jeor formula. Find your BMR and TDEE for weight loss or gain.
Speed Calculator
Calculate average speed from distance in miles and elapsed time in hours.
Force Calculator
Force Calculator with verified inputs, formula, and calculation logic.
Density Calculator
Calculate density from mass and volume with explicit gram and cubic-centimeter units.
Acceleration Calculator
Acceleration Calculator with verified inputs, formula, and calculation logic.
Molarity Calculator
Calculate solution molarity from moles of solute and final volume in liters.
Probability Calculator
Calculate probability using explicit client-side inputs.
Z-score Calculator
Calculate z-score from explicit statistical inputs.
Calculator menu
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Debt & Credit Calculators
Plan payoff order, credit utilization, consolidation, and borrowing costs with transparent estimates.
Mortgage & Loan Calculators
Compare home payments, amortization, affordability, refinancing, and personal-loan costs.
Savings & Investing Calculators
Project compound growth, retirement balances, inflation effects, and annualized investment performance with stated assumptions.
Health & Fitness Calculators
Explore educational estimates for body metrics, nutrition, exercise, and pregnancy timing with limitations stated.
Math & Everyday Utility Calculators
Solve common math, conversion, time, construction, science, and practical planning problems in the browser.
Built for useful answers
More than a number
A useful calculator should do more than return a result. Where supported, our calculator pages explain what the inputs mean, show the formula or method, include a worked example, and link to related tools so you can understand and act on the result.
Why use CalculatorFree
Privacy-first
Supported client-side calculators process inputs in your browser instead of requiring an account.
Instant results
Change an input and see the calculation update without a signup or page reload.
Real calculation logic
Published tools are connected to calculation logic, not just calculator names or empty metadata pages.
Clear methods
Calculator pages explain inputs, formulas, examples, assumptions, and related tools where available.