Days between dates, one time across cities, and an exact age — the three date questions that go wrong most often.
Counting days between two dates sounds like subtraction until you hit a month boundary, a leap year, or the question of whether you count both ends. “Three days from Friday” means different things to a project manager and a shipping system. Most date errors are not arithmetic errors — they are definition errors, and a good calculator makes the definition visible.
Date Calculator works in both directions. Give it two dates and it returns the difference in days, weeks and months, with the inclusive and exclusive figures shown separately so you can pick the one your deadline uses. Give it one date and an offset and it returns the resulting date, skipping or including weekends as you choose.
The month-length handling is where most hand calculations break: adding one month to 31 January lands on 28 or 29 February, not 31. That case is handled explicitly rather than silently rolling into March.
Time Zone Converter takes one time and shows it across the cities you add, with the date change flagged when a city has already crossed midnight. Daylight saving is applied per zone from the browser’s own time zone database, so a call scheduled for March is corrected for the week when North America and Europe switch on different dates — the single most common cause of a missed international meeting.
Age Calculator returns years, months and days rather than a decimal, because “34.7 years old” is not a thing anyone says. It also gives total days lived and a countdown to the next birthday, which is the version people actually want when filling in a form that asks for age in months, or when checking whether a visa deadline falls before or after a birthday.
Every calculation uses your device’s time zone unless you say otherwise, and the tool states which one it used. This matters more than it sounds: a date entered as 1 March in Tokyo is still February in London, and a countdown that ignores this is off by a day for half the planet. When a result looks wrong by exactly one day, the time zone is almost always the reason.
Each city is resolved through the browser’s IANA time zone database at the specific date you entered, not at today’s date. That means a call in late March is correct even though the two countries switch over on different weekends. Browsers update that database with the operating system, so recent rules are applied automatically.
Both figures are shown. The exclusive count is the plain difference — Monday to Wednesday is two days. The inclusive count treats both endpoints as days worked, which is what most leave requests and hotel bookings mean.
Yes, the date tool can skip weekends, so ten business days from a Friday lands two calendar weeks later rather than ten days later. Public holidays are not modelled, because they differ by country and change every year.
Everything on this site is free. All-Access removes the upgrade prompt and unlocks every tool.