Countdown Calculator
Compare a target timestamp with a stated reference timestamp to find the time remaining.
Result for the values shown.
Calculations run in your browser.
What to enter
| Input | Meaning and units |
|---|---|
| Target | Include seconds and an explicit Z or UTC offset, for example 2024-01-01T12:00:00Z. At most three fractional-second digits. |
| Reference timestamp | Include seconds and an explicit Z or UTC offset, for example 2024-01-01T12:00:00Z. At most three fractional-second digits. |
Understanding your result
The result compares explicitly dated instants using their offsets. A negative countdown indicates that the target is before the reference instant.
Common mistakes
- Comparing timezone-free clock strings as though they were fully specified instants.
Check your calculation
- Use a short known UTC interval; different offsets can describe the same instant.
Calculation checks, sources and review limits
How much time remains until a timestamp compared with a stated reference time?
Compare a target timestamp with a stated reference timestamp to find the time remaining.
Common uses
- Compare a target timestamp with a stated reference timestamp to find the time remaining.
How it works
remainingSeconds=targetEpochSeconds-asOfEpochSeconds Calendar arithmetic uses the proleptic Gregorian calendar. Explicit calendar dates are independent of local daylight-saving changes. Month/year additions clamp to the last valid day of the destination month. Timestamp arithmetic requires a stated UTC offset and excludes leap seconds.
Worked example
Enter Target: 2024-01-02T00:00:00Z; Reference timestamp: 2024-01-01T00:00:00Z. The result is Remaining seconds: 86400; Past: false.
FAQ
How much time remains until a timestamp compared with a stated reference time?
remainingSeconds=targetEpochSeconds-asOfEpochSeconds Calendar arithmetic uses the proleptic Gregorian calendar. Explicit calendar dates are independent of local daylight-saving changes. Month/year additions clamp to the last valid day of the destination month. Timestamp arithmetic requires a stated UTC offset and excludes leap seconds.
What assumptions and limits apply?
Use explicit asOf for fixtures; negative values indicate past target.