15 free calculators · no sign-up
Free online calculators for every calculation
Work out finance, maths, health, construction, dates, percentages and unit conversions in seconds. Every tool runs entirely in your browser — accurate, instant and completely free.
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The tools opened most often across the site.
Percentage Calculator
Answer all three percentage questions: X% of Y, X as a percent of Y, and the whole behind a percentage.
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Percentage Increase Calculator
Find the percentage rise between two values, or add a percentage to a starting number.
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Percentage Change Calculator
One tool for rises and falls — a signed percentage change measured from the original value.
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Discount Calculator
Find the sale price, the saving and the final cost after a discount — including stacked offers.
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Average Calculator
Mean, median, mode and range from one list of numbers, with the sorted data shown.
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Reverse Percentage Calculator
Recover the original figure from a price that already includes a markup, tax, discount or increase.
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Weighted Average Calculator
Average values that carry different importance — credits, portfolio sizes, category weights.
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Browse by category
Fifteen topic areas covering 15 calculators, each with its own worked examples and formulas.
Math Calculators
Fractions, roots, exponents, factors, primes and everyday arithmetic solved step by step.
5 calculators
Percentage Calculators
Percentage of a number, increase, decrease, change, difference, discounts and markups.
10 calculators
Finance Calculators
Loans, mortgages, compound interest, savings, retirement, investment returns and debt payoff.
0 calculators
Business Calculators
Margin, markup, break-even, ROI, pricing, cash flow, depreciation and growth metrics.
0 calculators
Salary & Tax Calculators
Salary conversions, hourly rates, overtime, take-home pay and rate-driven tax estimates.
0 calculators
Health & Fitness Calculators
BMI, BMR, TDEE, calories, macros, body fat, ideal weight, pace and hydration.
0 calculators
Date & Time Calculators
Days between dates, age, business days, date arithmetic, durations and time conversions.
0 calculators
Unit Conversion Calculators
Length, weight, temperature, volume, area, speed, energy, pressure and data conversions.
0 calculators
Construction Calculators
Concrete, paint, flooring, roofing, decking, fencing, gravel, drywall and material costs.
0 calculators
Geometry Calculators
Area, perimeter, volume and surface area for triangles, circles, polygons and solids.
0 calculators
Statistics Calculators
Mean, median, standard deviation, z-scores, confidence intervals, correlation and tests.
0 calculators
Science Calculators
Physics and chemistry: motion, energy, force, density, molarity, pH, gas laws and more.
0 calculators
Engineering Calculators
Electrical and mechanical: Ohm’s law, power, voltage dividers, energy cost and torque.
0 calculators
Education Calculators
GPA, weighted grades, final grade needed, test scores, percentages and study planning.
0 calculators
Everyday Calculators
Tips, bill splitting, discounts, fuel costs, unit pricing and other daily arithmetic.
0 calculators
Why use CalcVerse
Instant, offline-capable
Calculations run in your browser with plain JavaScript. Once a page has loaded it keeps working without a connection.
Your inputs stay put
Nothing you type is transmitted anywhere. There is no account, no server-side calculation and no analytics on your figures.
Formulas shown, not hidden
Every tool prints the formula it applies and the substituted working, so you can check the result rather than trust it.
Built for a phone first
Large touch targets, a numeric keypad on numeric fields, and the answer visible without scrolling on small screens.
A calculator for the question you actually have
Most calculator sites give you a box, a button and a number. That is fine until the number is not the one you needed — because “percentage change” and “percentage difference” are not the same calculation, because a loan quote assumes a compounding frequency nobody stated, or because a concrete estimate quietly ignored waste. CalcVerse is built around the idea that the framing matters as much as the arithmetic.
Every calculator names the exact question it answers, shows the formula it uses, and prints the substituted working beside the result. Where a convention is involved — 52 weeks in a year, 2,080 working hours, a 10% concrete waste allowance, the Mifflin-St Jeor equation for resting metabolism — the assumption is visible on the page and, wherever it is reasonable to do so, adjustable.
The whole library is static: HTML, CSS and vanilla JavaScript. There are no third-party APIs, no live market feeds and no keys to expire, which is why a page you loaded this morning still calculates correctly on a train with no signal. It also means the site never sees your salary, your weight or your loan balance — those values never leave the tab they were typed into.
Where to start
If you are here for a specific number, use the search box above — typing “bmi”, “mortgage” or “percent” gets you there in one keystroke each. If you are exploring, the 15 category pages each open with an explanation of what the tools in that area do and when to reach for one over another.
Common questions
Are these calculators free to use?
Yes. Every calculator on CalcVerse is free, with no account, no usage limit and no paid tier. The site is static HTML and JavaScript, so there is nothing to sign up for.
Do my inputs get sent anywhere?
No. All arithmetic happens in JavaScript inside your own browser tab. Nothing you type is uploaded, logged or shared. A few calculators remember your last inputs in your browser's local storage so the page is convenient to return to, and the health, finance and salary tools deliberately do not.
How accurate are the results?
The formulas are standard and are unit-tested against known values on every build. Where a result depends on an assumption — a compounding frequency, a waste allowance, a metabolic equation — the page states the assumption. Financial and health outputs are estimates, not advice.
Do the calculators work offline?
Once a calculator page has loaded, yes. Nothing depends on a network request, so you can lose your connection mid-calculation and the tool keeps working.
Why does the site not show live exchange rates or share prices?
Live data needs a third-party API, a key and a subscription, and it breaks the moment any of those lapse. CalcVerse deliberately uses only deterministic formulas, so a page that worked last year still works today. Where a rate is needed, you supply it.
Can I use these calculators on a phone?
Yes. The layout is built mobile-first with large touch targets, numeric keypads on numeric fields and the result visible without scrolling on small screens.