Utility Tools
Not every task is about code. These small utilities answer everyday date questions quickly and exactly — how old someone is on a given date, how many days are left until a birthday, or what date and time a Unix timestamp stands for.
2 free tools
Utility Tools
About these utility tools
Like every tool on this site, they run entirely in your browser. Dates you enter are not sent anywhere or stored.
Why use them
Calendar-exact
Ages are counted in whole years, months and days using real month lengths and leap years — not an average year length.
Time-zone safe
Calculations use calendar dates only, so daylight-saving changes and time zones can't shift the result by a day.
Private by default
Birth dates stay in your browser; nothing is uploaded or logged.
Frequently asked questions
Are my dates stored?
No. Calculations happen in your browser and the dates you type are not sent to a server or to analytics.
Why are these tools on a developer site?
Date arithmetic is a classic source of bugs. These utilities use the same careful calendar logic as the developer tools and are handy for checking expected values in tests, too.