Add Time Calculator

Add or subtract days, hours, minutes, and seconds from a starting date-time and get the resulting calendar date and time.

Frequently Asked Questions

Does the calculator handle leap years?

Yes. Adding 365 days to a leap-year date may give you the following year on the same calendar day or one day later, depending on which side of February 29 you start.

What format does it use?

ISO 8601 (YYYY-MM-DDTHH:MM) for input. Output is shown in the same format and as a localized string.

Can I add a negative duration?

Use subtract. The duration fields require non-negative numbers.

Important Disclaimer: Estimates for informational purposes only.

This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.