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Every calculator recomputes as you type — no submit button, no page reload.
49 tools · 14 categories
Free Online Calculators
Search hundreds of calculators and unit converters for math, finance, health, physics, geometry and everyday tasks. Each page is fast, mobile friendly and shows the formula it uses.
Calculator categories
Browse the full library by subject. Every category links straight to its calculators.
Arithmetic, percentages and everyday number crunching
All MathematicsLoans, savings, interest and business numbers
All FinanceLength, mass, volume, temperature and more
All Conversions
Durations, deadlines and age math
All Time & DateBody metrics, energy needs and training math
All HealthMotion, force, energy and density
All PhysicsSpread, probability and sampling
All StatisticsEquations, roots and proportions
All AlgebraAreas, volumes and triangle math
All GeometryMaterials, areas and project estimates
All ConstructionData sizes, transfer times and screens
All TechnologyRecipe scaling and kitchen measures
All CookingPace, splits and performance numbers
All SportsEveryday odds and ends
All MiscellaneousPopular calculators
The tools people reach for most often.
- Percentage CalculatorMathematics
- Loan Payment CalculatorFinance
- BMI CalculatorHealth
- Length ConverterConversions
- Compound Interest CalculatorFinance
- Standard Deviation CalculatorStatistics
- Circle CalculatorGeometry
- Date Difference CalculatorTime & Date
- Tip CalculatorMiscellaneous
- Running Pace CalculatorSports
- Quadratic Equation SolverAlgebra
- Concrete Slab CalculatorConstruction
Popular unit converters
Metric and imperial conversions with the exact factor shown.
Featured calculators
Hand-picked tools with worked examples and formula notes.
- Loan Payment CalculatorFinanceEstimate a monthly loan payment from the amount borrowed, annual interest rate and term, including total interest paid.
- Daily Calorie Needs CalculatorHealthEstimate basal metabolic rate and daily calorie needs using the Mifflin-St Jeor equation and an activity multiplier.
- Pythagorean Theorem CalculatorGeometryFind the hypotenuse of a right triangle from its two legs using a² + b² = c².
- Download Time CalculatorTechnologyEstimate how long a file takes to download at a given connection speed in megabits per second.
- Recipe ScalerCookingScale any recipe quantity up or down by changing the number of servings you need.
- Fuel Economy CalculatorMiscellaneousConvert fuel used and distance driven into litres per 100 km, km per litre and miles per gallon.
Shown working
Results include the formula and conversion factor so you can verify the method.
Private by default
Calculations run in your browser. We never store the numbers you enter.
All calculators A–Z
Every tool in the library, alphabetically.
- Age Calculator
- Aspect Ratio Calculator
- Average (Mean) Calculator
- Basic Calculator
- BMI Calculator
- Celsius to Fahrenheit Converter
- Circle Calculator
- Compound Interest Calculator
- Concrete Slab Calculator
- Daily Calorie Needs Calculator
- Data Storage Converter
- Date Difference Calculator
- Density Calculator
- Discount Calculator
- Download Time Calculator
- Fahrenheit to Celsius Converter
- Feet to Meters Converter
- Force Calculator
- Fuel Economy Calculator
- Kilograms to Pounds Converter
- Kilometers to Miles Converter
- Kinetic Energy Calculator
- Length Converter
- Linear Equation Solver
- Loan Payment Calculator
- Mean Median Mode Calculator
- Meters to Feet Converter
- Miles to Kilometers Converter
- Oven Temperature Converter
- Paint Calculator
- Percent Change Calculator
- Percentage Calculator
- Pounds to Kilograms Converter
- Profit Margin Calculator
- Proportion Calculator
- Pythagorean Theorem Calculator
- Quadratic Equation Solver
- Race Time Predictor
- Recipe Scaler
- Running Pace Calculator
- Speed Calculator
- Sphere Volume Calculator
- Standard Deviation Calculator
- Temperature Converter
- Tip Calculator
- Triangle Area Calculator
- Volume Converter
- Weight & Mass Converter
- Z-Score Calculator
About our free online calculators
Calculvira is a growing directory of free online calculators and unit converters. Instead of hiding the math, every tool shows the formula, the numbers substituted into it and the result, so you can check the working before you rely on the answer — whether you are doing homework, quoting a job or planning a budget.
To use a calculator, search for it in the box above or open a category such as Mathematics, Finance, Health or Geometry. Fill in the fields and results update as you type; there is nothing to submit and nothing to install. Each page also lists related calculators so you can move between connected problems, such as pairing a loan payment with a compound interest projection.
Unit converters cover length, mass, volume, temperature, data storage and cooking measures, and always display the conversion factor applied. Results are estimates provided for general information and are not financial, medical or engineering advice.