Calculators, converters and tools that show their work

293+ free tools for money, health, dates, units and everyday math. Every answer comes with the formula and the steps, runs privately in your browser, and loads in a blink on any phone.

    CalculatorsPaycheck, taxes, mortgage, retirement, health, home projectsConverters14 unit categories, 202 step-by-step conversionsToolsSpin the wheel, typing test, QR codes, timers, time zonesMathOnline and scientific calculators, fractions, algebra, statisticsElectricityOhm's law, AWG wire gauge, energy costWebASCII table, HTML colors, HTTP status codes

    Most popular

    Online CalculatorA fast, free online calculator with keyboard support, percent, memory keys and a tape of past calculations you can copy.Paycheck CalculatorEstimate take-home pay after federal income tax, Social Security, Medicare and state income tax for all 50 states, per paycheck, using 2026 tax rates.Spin the WheelAdd names or options, spin the wheel and let it pick a random winner.Typing TestTake a free typing speed test for 1, 2 or 5 minutes and get your words per minute, accuracy and a shareable score card, compared with typical typing speeds.Mortgage CalculatorCalculate your monthly mortgage payment, total interest and full amortization schedule.Percentage CalculatorSolve any percentage problem: X% of Y, X is what % of Y, percentage change, increase and decrease.Fraction CalculatorAdd, subtract, multiply and divide fractions and mixed numbers, then see every step: common denominators, simplifying and converting the answer to a decimal.QR Code GeneratorMake QR codes for links, Wi-Fi, text, email and phone numbers.Income Tax CalculatorEstimate your 2026 federal income tax, effective and marginal rate, and whether you will get a refund or owe, from income, filing status, deductions and withholding.Scientific CalculatorFree online scientific calculator: sin, cos, tan, logs, powers, roots, factorials and parentheses in degrees or radians.Ovulation CalculatorEstimate your fertile window and ovulation date from your last period and cycle length, and see the next three cycles.Concrete CalculatorCalculate concrete for slabs, footings, columns and steps in cubic yards, cubic feet and 40, 60 or 80 lb bags, with a waste allowance and a cost estimate.BMI CalculatorCalculate your body mass index in kg/cm or lb/ft-in, see the WHO category and your healthy weight range.Retirement CalculatorCheck whether your savings are on track: project your nest egg at retirement, how long it lasts with withdrawals and inflation, and how much more to save monthly.Amortization CalculatorBuild a full amortization schedule for any loan or mortgage.Loan CalculatorWork out the monthly payment (EMI), total interest and payoff schedule for any personal, car or business loan.

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    Games, tests and generators

    Spin the WheelAdd names or options, spin the wheel and let it pick a random winner.Flip a CoinFlip a virtual coin for heads or tails.Dice RollerRoll one or more dice online: standard six-sided dice or d4, d8, d10, d12 and d20 for tabletop games.Typing TestTake a free typing speed test for 1, 2 or 5 minutes and get your words per minute, accuracy and a shareable score card, compared with typical typing speeds.CPS TestTest how many clicks per second you can do in 1, 5, 10 or 60 seconds.Reaction Time TestTap when the screen turns green to measure your reaction time in milliseconds.QR Code GeneratorMake QR codes for links, Wi-Fi, text, email and phone numbers.Zodiac Sign CalculatorFind your sun, moon and rising (ascendant) signs from your birth date, time and place, calculated from astronomical positions, plus the dates for every sign.

    Timers and countdowns

    Quick conversions

    Guides

    How much house can I afford?Money guide with worked examples72-month vs 60-month car loans: what the longer term really costsMoney guide with worked examplesCompound interest explained, with real examplesMoney guide with worked examplesHow to calculate a calorie deficit to lose weight safelyHealth guide with worked examples

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    Shows the workingFormulas and step-by-step working with your own numbers, so you can check and learn.
    Private by defaultCalculations run in your browser. What you type is not uploaded.
    Fast everywhereNo heavy frameworks or pop-ups — pages load instantly, even on slow mobile data.
    Checked and sourcedTested against reference values and linked to official sources. How we check

    For the UAE and the Gulf

    Tools built around local rules and rates, explained with official sources.

    VAT CalculatorAdd VAT to a net price or extract VAT from a gross price.UAE Gratuity CalculatorEstimate your UAE end-of-service gratuity under Federal Decree-Law No. 33 of 2021: 21 days per year for 5 years, then 30 days.Zakat CalculatorCalculate zakat at 2.5% on cash, gold, silver, investments and business assets, checked against the gold or silver nisab you choose.

    About Reeliy

    Reeliy is a free collection of calculators, unit converters and everyday tools. We build each tool from the underlying formula, test it against independent reference values, and write a plain-English explanation alongside it — including its limits. If something looks wrong, tell us and we will fix it.