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ISO 8601 duration converter

Enter an ISO 8601 duration to break it down and convert it to seconds.

How ISO 8601 duration converter works

ISO 8601 duration parser breaks down a duration string in the P1Y2M3DT4H5M6S format into its human-readable components, years, months, days, hours, minutes, seconds, and also gives the total in seconds for quick comparisons. It is the tool for developers and data engineers who work with ISO 8601 durations in APIs, databases, calendaring systems and standards-compliant date arithmetic.

This is distinct from the Time duration tool, which works with two plain clock times and is aimed at everyday use. And it is distinct from the Timesheet tool, which is for tracking worked hours. ISO 8601 duration parser is narrowly focused on the standard format and its numeric decomposition, and it also works in reverse, assembling a canonical duration string from individual year, month, day and time values.

Frequently asked questions

Is the ISO 8601 string I paste sent to a server for parsing?

No. Parsing is done by JavaScript running in your browser. The string you enter stays on your device and is never transmitted to Sunasty or any external service.

What is the ISO 8601 duration format?

It starts with P (for "period"), followed by date components (Y years, M months, W weeks, D days), then a T separator before time components (H hours, M minutes, S seconds). For example P1Y6M means one year and six months; PT2H30M means two hours and thirty minutes.

Can it convert the other way, from components to an ISO 8601 string?

Yes. Enter individual year/month/day/hour/minute/second values and the tool assembles the canonical ISO 8601 duration string for you, ready to paste into your API payload or code.

Does it work offline?

Yes, once the page has loaded. Because the processing happens on your device, you can disconnect from the network and the tool keeps working. This is the clearest proof that your data never leaves your machine.

Is it free? Do I need an account?

It is completely free and requires no sign-up. There are no watermarks, no daily limits and no tracking cookies needed to use the tool.