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Calculators, converters, generators and checkers — free, fast and checked by our research team. Filter by type or topic to find the right one.
Age Calculator
Enter a date of birth to get the exact age in years, months and days —…
Aspect Ratio Calculator
Work out the missing width or height for any aspect ratio — or find the ratio…
BMI Calculator
Calculate your body mass index from your height and weight — with the WHO category, the…
Calorie Calculator
How many calories do you need a day? Find your maintenance calories and daily targets to…
CPC Calculator
Work out cost per click from your budget and clicks — or how many clicks a…
CPM Calculator
Work out cost per mille — the price of 1,000 ad impressions — or the budget…
Days Between Dates Calculator
Count the days between two dates — with weeks, months, business days and hours — or…
Margin Calculator
Enter any two of cost, selling price, profit, margin or markup — the calculator fills in…
Password Generator
Create strong, random passwords in one click. Choose the length and characters — everything happens in…
Percentage Calculator
Work out a percentage of a number, what percent one number is of another, or the…
ROI Calculator
Calculate the return on investment of any project: how much you gained as a percentage of…
Steps Calculator
Convert your steps into distance, calories and walking time — or find how many steps a…
Test Grade Calculator
Enter the number of questions and how many you got wrong to get your percentage and…
Time Calculator
Add or subtract days, hours, minutes and seconds — or add a length of time to…
Free online tools you can trust
Every tool is built from a documented formula or standard, written by a subject specialist and checked by a second reviewer before it goes live. We show the method under each tool so you can verify the result yourself.
All tools are free, work in your browser and don’t require an account.
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