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Free online calculators for finance, health, math, and everyday life. Fast, accurate, mobile-friendly, and ad-light — no sign-up required.
50 tools, organised by what you want to do
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A real calculator, right here — switch to Scientific for functions, powers and trig.
Browse calculators by task
- Borrow & RepayWhat will borrowing really cost me?Work out the true cost of a mortgage, car loan, personal loan or credit-card balance — the monthly payment, the total interest, and how fast you clear it.8 calculators
- Save & InvestHow much will my money grow?See how savings and investments grow over time — compound interest, monthly contributions, retirement projections and what inflation does to it all.7 calculators
- Income & TaxWhat's my real pay, tax and price?Understand the money that moves every day — convert a salary between hourly and yearly, estimate income tax, add or remove sales tax, and split a bill with tip.5 calculators
- Health & FitnessWhere do my body, diet and training stand?Turn a few measurements into the numbers that guide health decisions — BMI, body fat, ideal weight, calories, protein, heart-rate zones and running pace.11 calculators
- Dates & TimeHow much time is between these?Dates and durations done exactly — your precise age, the days between two dates, adding or subtracting time, and hours worked between two clock times.4 calculators
- Measure & ConvertHow much space or material do I need?From a home project to a homework problem — square footage, area, volume, triangles and concrete, plus a converter for length, weight and temperature.6 calculators
- Math, School & ToolsCan you crunch this number for me?Everyday and advanced math plus a few handy utilities — a scientific calculator, percentages, fractions, statistics, GPA and grades, and a password maker.9 calculators
- Prefer to browse?See every calculator in one searchable list.All 50 calculators →
Popular calculators
View all →- Mortgage CalculatorEstimate your monthly mortgage payment including principal, interest, property tax, insurance and PMI, and a year-by-year amortization schedule.Open →
- BMI CalculatorCalculate your Body Mass Index (BMI) from height and weight, see your WHO weight category, and your healthy weight range.Open →
- Percentage CalculatorWork out a percentage of a number, what percent one number is of another, and percentage increase or decrease — three calculators, each showing its steps.Open →
- Scientific CalculatorA free online scientific calculator with trigonometry, logarithms, powers, roots, factorials, memory and constants — works on any device.Open →
- Loan CalculatorCalculate the monthly payment, total interest and payoff date on any fixed-rate loan, with a full amortization schedule and the saving from paying extra.Open →
- Calorie CalculatorFind your daily calorie needs for maintaining, losing or gaining weight, from your age, height, weight and activity level, with a macro breakdown.Open →
- Compound Interest CalculatorConvert an interest rate between compounding periods — APR to APY and back — so two quotes can be compared on equal terms.Open →
- Age CalculatorCalculate your exact age in years, months and days from your date of birth, plus total weeks, days and hours lived, and the time to your next birthday.Open →
- Tip CalculatorCalculate the tip and the total, then split the bill between any number of people. Pick a percentage or round to a figure and see what each person pays.Open →
From our guides
All guides →- HealthThe Complete Guide to Healthy WeightHow BMI, body fat, BMR and calories fit together — a practical, no-fads framework for reaching and maintaining a healthy weight, backed by the numbers.Read guide →
- FinanceHow Loans and Interest Really WorkA jargon-free guide to borrowing — interest vs. APR, simple vs. compound, amortization, the main loan types, and how to pay less over the life of a loan.Read guide →
- FinanceInvesting for Beginners: How to StartA plain-English starter guide to investing — why compounding matters, how to think about risk, what to actually invest in, and how to begin with any budget.Read guide →
Why BestCalculate
Instant & accurate
Results update as you type, using formulas that are unit-tested for correctness.
Private by design
Every calculation runs in your browser. Nothing you enter is sent to a server.
Free, no sign-up
No accounts, no paywalls, no clutter — just the tool you came for.
Works everywhere
Fast and responsive on phones, tablets and desktops, online or offline once loaded.
Tools you can trust
Accuracy is the whole point of a calculator. Every formula on BestCalculate is implemented transparently and backed by an automated test suite, and each tool is reviewed against authoritative sources before it goes live. We show our working in every calculator's explainer so you can understand — not just trust — the result.
How we build our calculators