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54 calculators · 35 categories · free

Everyday calculators, instant answers.

Money, health, school, home and more. No sign-up, results as you type, formulas explained.

Not sure which calculator? Describe your problem

Popular calculators

Percentage CalculatorX% of Y, percentage change and reverse percentages.Loan Payment CalculatorMonthly payment and total interest for any loan.BMI CalculatorBody mass index from weight in kilograms and height in metersROAS (Return on Ad Spend) CalculatorRevenue earned for every dollar spent on ads, from ad revenue and ad spendKilograms to PoundsConvert weight from kilograms to pounds (lbs)Tip CalculatorTip amount and the per-person split.VAT / Sales Tax CalculatorAdd or remove VAT and sales tax from any price.Compound Interest CalculatorFuture value of savings or an investment with interest compounded several times a year

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All calculators A–Z →
Basic Math8 calculatorsFinancial8 calculatorsHealth & Fitness2 calculatorsEducation2 calculatorsShopping & Discounts4 calculatorsHome & Construction2 calculatorsDate & TimeComing soonAutomotive & Travel2 calculatorsCooking & FoodComing soonBusiness & Freelance4 calculatorsUnit Conversion7 calculatorsGeometry3 calculatorsTax1 calculatorReal EstateComing soonTechnologyComing soonLifestyleComing soonScienceComing soonPhysics1 calculatorChemistryComing soonElectrical1 calculatorEngineeringComing soonStatistics1 calculatorProbabilityComing soonSportsComing soonPregnancy & ParentingComing soonGardeningComing soonPetsComing soonClothing & FashionComing soonPhotography & VideoComing soonMarketing & SEO7 calculatorsE-commerce1 calculatorLogisticsComing soonEnvironmentalComing soonAviation & NavigationComing soonCalendars & EventsComing soon

Recently added

Conversion Rate CalculatorPercent of visitors who bought, signed up or converted, from conversions and total visitorsCPC (Cost per Click) CalculatorAverage cost per click of an ad campaign from total ad cost and number of clicksCPM (Cost per 1,000 Impressions) CalculatorAdvertising cost per thousand impressions or views from total ad cost and impressionsCTR (Click-Through Rate) CalculatorPercent of people who clicked an ad, email or link, from clicks and impressionsCustomer Acquisition Cost (CAC) CalculatorAverage cost to win one new customer from total marketing and sales spend and new customers gainedCustomer Lifetime Value (CLV) CalculatorHow much revenue one customer brings over time from average order value, purchases per year and years as a customer

How it works

  1. 1. Pick a calculator

    Search, browse a category, or describe your problem to the helper.

  2. 2. Enter your numbers

    Results update instantly as you type — there's no button to press.

  3. 3. Read the answer

    See the result with the formula and a plain-English explanation.

Instant results

Answers update as you type.

Formulas shown

Every result shows how it's worked out.

Private by default

Calculator inputs stay in your browser.

Frequently asked questions

Are CalClu calculators free?

Yes. Every calculator is free to use and you never need an account to calculate. A free account is optional.

Do I need to sign up?

No. Open any calculator and start typing — results appear instantly. Accounts are only for extras like saving calculations, which are coming soon.

How accurate are the results?

Calculators use standard, published formulas and show how the answer is worked out. Results are estimates for general information; for important financial, medical, legal or engineering decisions, check with a qualified professional.

Can't find the calculator I need?

Search with Ctrl K, browse the 35 categories, or describe your problem in plain words in the helper box at the top of this page and it will point you to the right calculator.

Does CalClu work on my phone?

Yes. Every page works on phones, tablets and computers, with large tap targets and a dark theme option.