Time Converter

How to convert time units

Enter a duration, pick the unit it is in, and pick the unit you want. The result and the whole ladder from milliseconds to years update as you type, entirely in your browser.

The second is the internal base. The small units (ms, s, min, h, d, wk) are exact. The month and the year are fixed at 30 and 365 days, so treat them as approximations rather than calendar facts.

• Type the duration in the Value box, for example 90.
• Pick the From unit, for example Minute.
• Pick the To unit, for example Hour.
• Read the result and scan the table for seconds and milliseconds if you are feeding a config or a timeout.
• For anything that must respect a real calendar, do the month and year math elsewhere.

Where the exact units stop and the approximations begin

Six of the eight units are exact and always will be. A millisecond is a thousandth of a second, a minute is 60 seconds, an hour is 3,600, a day is 86,400, and a week is 604,800. None of those numbers depends on a calendar, a season, or a country, which is why software timers, cron expressions, cache lifetimes, and rate limits are all expressed in them.

The month and the year are different. A calendar month runs from 28 to 31 days and a calendar year from 365 to 366, so any converter has to pick a fixed stand-in. This one uses 30 days and 365 days respectively. That makes them useful for a rough sense of scale and wrong for anything that has to line up with a real date, which is the distinction most conversion mistakes come down to.

• Exact: ms, s, min, h, d, wk.
• Fixed approximations: month = 30 d, year = 365 d.
• Never exact here: leap years, leap seconds, and calendar month lengths.

Durations in configuration files and code

Most of the traffic to a time converter is someone translating a human duration into the unit a config file wants. A cache header wants seconds, a JavaScript timer wants milliseconds, a Kubernetes probe wants seconds, and a cron comment wants minutes. Typing the human figure once and reading the row you need is faster than doing the multiplication in your head and safer than doing it wrong.

The classic errors are all order-of-magnitude slips: a 30-minute cache written as 30 instead of 1,800 seconds, a 5-second timeout written as 5 instead of 5,000 milliseconds, or a one-day expiry written as 24 rather than 86,400. Reading the value off the table removes the arithmetic step where those happen.