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Calculators That Show Their Working

Most calculator sites hand you a number and nothing else. Every CalculatorPlus tool shows the formula it used and walks through a worked example, so you can check the answer instead of trusting it.

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Browse by Category

Pick a category to see every calculator in it. Each tool runs instantly in your browser — nothing is uploaded, and there is no sign-up.

Construction & Materials

Estimate materials, volumes and coverage for any build or landscaping job.

13 calculators

Finance & Money

Loans, taxes, investing and everyday money math, with every rate sourced.

21 calculators

Algebra & Math

Algebra, geometry and everyday math with step-by-step working shown.

25 calculators

Health & Medical

Dosage, fluids and health math — educational tools with cited formulas.

14 calculators

Legal & Insurance

State child support, estate tax, settlements and insurance estimates.

6 calculators

Calculus & Symbolic Math

Derivatives, integrals and transforms, worked symbolically and numerically.

7 calculators

Sports & Hobbies

Scoring, sizing and gear math for sports and hobbies.

7 calculators

Physics & Engineering

Energy, motion, power and mechanics with the equations shown.

6 calculators

Biology & Genetics

Inheritance, blood type and population math made visual.

9 calculators

Statistics & Probability

Regression, distributions and variance, computed in the browser.

9 calculators

Automotive & Racing

Quarter-mile, power and performance estimates for gearheads.

5 calculators

Chemistry

pH, enthalpy and concentration math with equations shown.

8 calculators

Sewing & Crafts

Fabric, thread and pattern math for makers.

4 calculators

Education & Academic

GPA, grades and academic math for students.

8 calculators

Food & Baking

Baker's math and recipe ratios that actually work.

3 calculators

Lifestyle & Misc

Dates, breaks and everyday odds and ends.

5 calculators

Popular Calculators

Cubic Yard Calculator

Convert length, width and depth into cubic yards for concrete, gravel, dirt or mulch.

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Reverse Sales Tax Calculator

Strip sales tax out of a total to find the pre-tax price and the tax paid.

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Break-Even Calculator

Find how many units you must sell to cover fixed and variable costs.

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Discriminant Calculator

Find b² − 4ac and what it tells you about a quadratic's roots.

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Perimeter Calculator

Find the perimeter of a rectangle, square, triangle or circle.

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mg to mL Calculator

Convert a drug dose in milligrams to a volume in millilitres using its concentration.

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Why the Working Matters

A calculator that only shows a result is impossible to sanity-check. When the number looks wrong, you have no way to tell whether the tool made a mistake or you typed the wrong input.

Every tool here publishes the formula it uses and a worked example underneath, so you can verify the result in about thirty seconds. Where a calculation depends on a tax rate, bracket or price set by an outside authority, we cite the source, show the date we last checked it, and let you edit the number if it has since changed.

Built to Be Fast and Honest

  • Runs entirely in your browser — no data leaves your device
  • The formula and a worked example are shown on every page
  • Rates and brackets are cited to their source and dated
  • Educational tools carry a plain disclaimer where the stakes are high
  • Works on your phone without pinching or zooming

Latest Guides

How to Calculate Cubic Yards (Without Getting It Wrong)

The ÷27 rule, why depth in inches trips everyone up, and how much extra to order.

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Reverse Sales Tax: How to Find the Price Before Tax

Why you divide instead of subtract, and the mistake that makes the tax look bigger than it is.

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How to Calculate Your GPA (College and High School)

The credit-weighted method, the 4.0 grade-point scale, and why credit hours change everything.

Read guide →

Frequently Asked Questions

Are the calculators free to use?

Yes. Every calculator on CalculatorPlus is free, needs no account, and runs entirely in your browser. The site is supported by display advertising, never by charging for the tools.

Do you store the numbers I enter?

No. Calculations happen locally in your browser and nothing you type is sent to a server or saved. Refreshing the page clears everything.

How do I know a result is correct?

Each tool shows the exact formula it uses and a worked example with real numbers. You can follow the same steps by hand to confirm the answer, and every formula's source is stated on the page.

Looking for a different calculator?

CalculatorPlus has free tools across finance, construction, math, health and more — each one showing the formula and a worked example.

Browse All Calculators How We Check Accuracy