Count days or working days
Date CalculatorChoose endpoints, weekends and extra days off. Check whether the boundary dates count.
Calculators & dates tools
Choose calendar arithmetic or measurement conversion. A calendar month is not a fixed number of days, and an age is not simply elapsed seconds divided by a year.
Which tool fits your job?
Calculate calendar age and milestones
Age CalculatorUse the birth date for calendar age. Life-statistic estimates have separate assumptions.
Convert a measurement
Unit ConverterChoose units or type a command. Read the factor or formula alongside the result.
3 tools ready to use
Search and filter these toolsDates
Date CalculatorCount days between dates, add or subtract time and skip days off. Turn your result into a shareable date card.No file neededOpen toolLocal processingAge CalculatorSee your age in days, minutes and seconds. Explore life in numbers, find your next milestone and make a keepsake poster.No file neededOpen toolLocal processing
Measurements
Before you start
Month ends and leap days can change a result. Check endpoint choices and units. Life-statistic cards use estimates, and personal dates stay out of discovery analytics.
Guides for these tools
How to count days between datesChoose your endpoints, skip non-working days and understand month ends. Check the same dates in a spreadsheet.How to calculate age, days lived and life statisticsUnderstand calendar age, elapsed seconds, leap-day birthdays and the assumptions behind life-in-numbers cards.How to convert units: factors and roundingA reliable factor method for length, area, volume and temperature, with worked examples and the rounding mistakes that change an answer.
2 more in build
Named and planned, with no working page or promised release date.
Scientific CalculatorFull keyboard entry, a visible tape of what you typed, and no ads between you and the answer.In build
Percentage CalculatorPercentage of, increase, decrease and change, each with the working shown.In build