Countup Timer
Countup Timer — runs in your browser. Inputs are not stored.
Count-up timer
Enter values, then press Calculate.
Shows elapsed time in real time from the start you set until now.
How to use
- Enter a start datetime or leave it empty. Empty plus Start fills the start datetime with now.
- Press Start so status becomes running and elapsed time grows from 00:00:00 by the second.
- A past datetime shows elapsed from then until now immediately. Use it for a quit-smoking or workout start date.
- Pause sets status to paused and freezes the numbers. Start again continues from the same start datetime.
- Reset sets elapsed to 00:00:00 and status to idle. It does not clear the start datetime field.
- A broken datetime format shows an invalid datetime status. Pick again from the calendar field.
Key concepts
A count-up timer shows now minus start time. A countdown shrinks time left; this grows time already passed. It uses device local time and does not sync with a server.
Past one day, a day count prefixes elapsed. For date-only D-Day notation, the D-day calculator is simpler. For lap splits, use a stopwatch. Values stay in the browser tab. Refreshing resets the elapsed display; if the start datetime field still has a value, press Start again to count from that origin. For official tenure or legal start dates, follow the HR system date.
Example
If you quit smoking at 00:00 on the 1st of last month, put that in start datetime and Start. Days, hours, minutes, and seconds until today appear as elapsed. To count from now, leave start datetime empty and press Start to fill now. To keep the same start time every day like a workout streak, do not clear the field—just press Start again.
Related: countdown timer · stopwatch · D-day calculator
Frequently asked questions
What if I leave the count-up timer start datetime empty?
The local time when you press Start is filled into start datetime automatically, and elapsed counts from then.
How does a count-up timer differ from a stopwatch?
A stopwatch has laps and tenths of a second and no datetime input. Count-up shows elapsed from a specific start datetime as days, hours, minutes, and seconds.
Can I count up from a past date?
Yes. Elapsed from then until now appears immediately. A future datetime can show elapsed as 0.
Are count-up timer values saved on a server?
No. Calculation runs only in the browser and disappears when you close the page.
If I pause the count-up timer then start again, does elapsed reset?
If the start datetime is unchanged, elapsed from that origin is counted again. Full reset is the Reset button.
Should I use the D-day calculator or the count-up timer?
For date-only D−n, use D-day; to see how many seconds have passed, use the count-up timer.
Last reviewed: 2026-09-04