Time Duration Calculator
Compose or expand durations between total seconds and days/hours/minutes/seconds.
Tool workspace
Fractional seconds are truncated toward zero (not rounded).
Compose duration parts into total seconds, or expand total seconds into days/hours/minutes/seconds. Pure duration math — no timezone conversion.
How it works
Compose mode sums days/hours/minutes/seconds into a normalized breakdown and total seconds. Expand mode converts total seconds into the same parts.
Rounding: fractional total-seconds input is truncated toward zero (not rounded). This is pure duration math — no timezone conversion. Empty inputs clear the result—no error.
Rounding: fractional total-seconds input is truncated toward zero (not rounded). This is pure duration math — no timezone conversion. Empty inputs clear the result—no error.
Examples
- 1 hour + 1 minute + 1 second → 0 days, 1 hour, 1 minute, 1 second = 3661 total seconds
- 3661.9 total seconds → truncated to 3661 seconds
Privacy
Privacy: this tool processes values locally in your browser. We do not log or store what you enter. Login is not required.
FAQ
Does this use my timezone?
No. Duration composition does not involve clock timezones.
How are fractions handled?
Fractional total seconds are truncated toward zero.
Do I need an account?
No. All published tools work for guests without login.