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Free Online Calculators

209 free tools for finance, health, math, conversions and everyday questions—all processed locally in your browser.

  • 209 free calculators
  • No registration
  • Mobile friendly
  • Nothing leaves your device
Browse all 209 tools Try the mortgage calculator

Browse by category

Four groups covering 209 calculators.

Financial Calculators

Borrow, invest and plan with the real numbers in front of you.

Fitness and Health Calculators

Body composition, energy needs and training targets.

Math Calculators

Algebra, geometry, statistics and number theory.

Other Calculators

Conversions, dates, construction, networking and utilities.

Most used

The tools people reach for most often.

Mortgage BMI Compound Interest Loan Percentage TDEE Auto Loan Age Conversion Standard Deviation Income Tax Scientific

How it works

No sign-up, no waiting, no data collection.

  1. 1

    Find your calculator

    Search from any page — press / to jump straight to the box — or browse the four categories.

  2. 2

    Enter your numbers

    Every field is pre-filled with a realistic example. Results update as you type, so there is no submit button to hunt for.

  3. 3

    Read the full picture

    Not just one number — the breakdown, the schedule, and an explanation of what the result actually means.

Financial Calculators

Financial decisions turn on figures that are easy to guess at and hard to picture. A quarter point on a mortgage rate looks trivial until you see it compounded across thirty years; a minimum credit-card payment looks manageable until you see the payoff date. These calculators show the whole shape of a decision — the monthly figure, the lifetime cost, and the schedule underneath.

Every loan tool produces a full amortization schedule, so you can see exactly how each payment splits between interest and principal and what you would still owe at any point. Tax and retirement calculators keep statutory figures as editable inputs rather than hard-coded constants, and show the jurisdiction and basis year alongside the result.

View all 80 finance tools

Fitness and Health Calculators

Health calculators translate a couple of measurements into something you can act on: a calorie target, a training zone, a body composition estimate. They apply population-level equations to an individual, which makes them genuinely useful for tracking direction over time and unreliable as a verdict on any single day.

Where several accepted formulas exist — BMR, body fat, ideal weight — the tools show all of them rather than picking one silently, because the spread between them tells you how much confidence the number deserves. Each page explains what the measure misses as well as what it captures.

View all 34 health tools

Math Calculators

From evaluating an expression to running a full descriptive statistics pass over a data set, these tools handle the mechanical part so you can concentrate on the interpretation. Calculations run in double precision and display rounded values while retaining full accuracy internally.

The statistics tools implement the distributions properly — normal, t, chi-square — rather than approximating from lookup tables, so p-values and confidence intervals are accurate across the full range. Geometry tools return every derived property, not just the one you asked for.

View all 44 math tools

Other Calculators

The practical tools: converting between units, counting working days, sizing a concrete pour, subnetting a network, checking fuel economy. Small questions that are quick to answer wrongly in your head.

Conversion factors and physical constants are the standard published values. Where a result depends on a material property, a local code or a regional convention, that value is exposed as an input so you can match it to your situation rather than accepting a US or metric default.

View all 51 everyday tools