Free Online Calculators
53 free online calculators for money, health, maths and everyday questions, from mortgage repayments and BMI to percentages, fractions and unit conversion. Each one explains its formula, and nothing you type leaves your browser.
All 53 calculators, grouped by category
Financial Calculators
5 calculators
Loans, mortgages, interest, returns and VAT: plan the numbers before you commit.
Fitness & Health Calculators
5 calculators
BMI, energy needs, body fat and heart-rate zones for general wellness planning.
Math Calculators
38 calculators
Algebra, number theory, statistics and geometry tools with the working shown.
General maths
- Scientific Calculator
- Fraction Calculator
- Percentage Calculator
- Random Number Generator
- Percent Error Calculator
- Exponent Calculator
- Binary Calculator
- Hex Calculator
- Half-Life Calculator
- Quadratic Formula Calculator
- Log Calculator
- Ratio Calculator
- Root Calculator
- LCM Calculator
- GCF Calculator
- Factor Calculator
- Rounding Calculator
- Matrix Calculator
- Scientific Notation Calculator
- Big Number Calculator
Statistics & probability
Other Calculators
5 calculators
Dates, ages, tips, fuel costs and unit conversion for everyday questions.
How these free online calculators work
Every calculator has its own page with the inputs explained, the formula written out, a worked example and the assumptions behind the answer, so you can check the result instead of just trusting a number. They are grouped into financial, fitness and health, maths and everyday tools.
The calculations run in your browser. Where conventions differ between countries, such as VAT versus sales tax, EMI versus mortgage payment, litres per 100 km versus miles per gallon, or stone versus kilograms, the page says what it assumes. Results are estimates for planning and learning, not professional financial, medical or legal advice.
Calculator questions
The collection has 53 calculators in four groups: financial (mortgage, loan, compound interest, ROI and VAT), fitness and health (BMI, BMR, calories, body fat and heart-rate zones), maths (arithmetic, algebra, statistics and geometry) and everyday tools (age, dates, tips, fuel cost and unit conversion).
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