208 free tools · no sign-up

Every calculator you need, in one clean place.

Fast, accurate, mobile-friendly calculators and converters for finance, health, math, dates and everyday life — all free.

Mortgage Calculator Percentage Calculator BMI Calculator Scientific Calculator Date Calculator Tip Calculator Loan Calculator Calorie Calculator

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45 tools

Financial Calculators

Loans, mortgages, savings, investing and money math

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31 tools

Fitness & Health

Body metrics, calories, nutrition and wellness

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49 tools

Math Calculators

Percentages, statistics, geometry, algebra and number tools

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21 tools

Converters

Length, weight, temperature, speed and more

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18 tools

Date & Time

Dates, ages, durations and day counting

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44 tools

Other Calculators

Everyday, home, auto, weather and developer utilities

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Financial Calculators

Mortgage Refinance Auto Loan Compound Interest Credit Card Payoff Loan Salary Income Tax Simple Interest Interest Payment Amortization View all 45 →

Fitness & Health Calculators

BMI Calorie BMR Ideal Weight Body Fat TDEE Macro Protein Carbohydrate Fat Intake Lean Body Mass Pace View all 31 →

Math Calculators

Percentage GCF Average Standard Deviation Fraction Triangle Scientific Exponent Log Root Ratio Percent Error View all 49 →

Converters

Length Weight Temperature Speed Roman Numeral Byte Timezone Age in Seconds Morse Code Translator Binary Text to Binary JSON Formatter View all 21 →

Date & Time Calculators

Date Day Counter Age Time Hours Time Duration Time Card Date Time Countdown Timer Business Days Meeting Time Finder Sunrise Sunset View all 18 →

Other Calculators

Square Footage URL Encode / Decode Tip GPA Grade Password Generator Base64 Encode Decode Fuel Cost Gas Mileage Mileage Concrete Tile View all 44 →

From the Blog

Finance How to Use the Mortgage Calculator Step-by-step guide to estimating payments and comparing loan scenarios. Health Understanding Your BMI Results What your BMI number means and its limitations. Finance The Power of Compound Interest How compounding works and how to project your savings.

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Free online calculators for everything

123calcs is a growing collection of 208 free calculators and converters built to be fast, accurate and pleasant to use. Whether you are planning a mortgage, checking your BMI, solving a maths problem, converting units or counting the days to a deadline, every tool runs instantly in your browser with no sign-up and no downloads.

Organised by category

Tools are grouped into finance, health, math, converters, date & time, and other utilities, each with its own page so you can browse everything in one place. Use the search box above to jump straight to any calculator.

Always free

All tools are completely free. We keep the site running with unobtrusive ads, so you can calculate as much as you like.