The 138 Hour Timer on FinalTimer.com is a free countdown for 5 days and 18 hours. It runs in any browser, works in fullscreen and alerts you with one of 13 alarm sounds when the 138 hours are over.
When a 138 Hour Timer Comes in Handy
A 138 hour timer is useful in many situations:
- Contest or Giveaway: Run a contest, a giveaway or a sign-up phase with a visible end date for all participants.
- Product Launch: Show the whole team how much time is left until launch. A shared countdown creates focus and urgency.
- Fermentation: Sauerkraut, kimchi and kombucha ferment for days to weeks, and the 138 hour timer reminds you when to taste.
- Project Deadline: Visualise the time left until a deadline. 5 days and 18 hours feels very different when you see it ticking.
- Exam Countdown: See how many days are left until the exam and plan your revision backwards from the deadline.
Fun Fact About 138 Hours
The dramatic Apollo 13 mission of April 1970 lasted 142 hours and 54 minutes. The 138 hour timer is just 4 hours and 54 minutes shorter than that.
In binary, the language of computers, 138 is written as 10001010, a 8-digit number.
How to Set a 138 Hour Timer
- The timer at the top of this page is already set to 5d 18:00:00. Simply press Start Timer.
- Give your countdown a name in the text field, switch on the alarm and pick the sound you like best.
- Combine the 138-hour block with breaks or other phases by adding timers; the whole sequence runs on its own.
- Switch to fullscreen for big digits and save your configuration with Export Settings to load it again later.
Tip for long timers: leave the page open in a pinned tab and keep your device charging. The timer uses the actual clock time, so it stays accurate for the full 5 days and 18 hours.
Recommended Timers for Specific Activities
Want more than a single countdown? These presets combine several timers into a routine:
- For mindfulness and calm breathing, the Meditation Timer guides you through every phase.
- For structured workout sessions, try the HIIT Workout Timer with work and rest intervals.
- Prefer longer focus blocks? The 52/17 Productivity Timer alternates 52 minutes of work with 17 minutes of rest.
- Creators plan writing, filming and editing with the Content Creation Timer.
More Timer Options
Frequently Asked Questions About the 138 Hour Timer
How long is a 138 hour timer?
A 138 hour timer runs for exactly 5 days and 18 hours. That equals 496,800 seconds, 8,280 minutes or 5.75 days.
Can I pause or repeat the 138 hour timer?
You can pause at any moment (also with the space bar) and resume exactly where you stopped. To run the 138 hours several times, switch on Repeat Timer and choose how often.
Will I hear an alarm when the time is up?
Activate Enable Alarm, pick one of the 13 sounds and the 138 hour timer will ring when it reaches zero. Make sure the tab stays open and your device is not muted.
Does the timer keep running if my computer goes to sleep?
The countdown is calculated from the real clock time. If your device sleeps, the display jumps to the correct remaining time when it wakes up. The alarm itself can only play while the device is awake, so for long timers keep it plugged in and disable sleep mode. If you reload the page, FinalTimer offers to resume the running timer.
Make Every Second of the 138 Hour Timer Count
Even a single countdown can change the way you manage time. Use the 138 hour timer as often as you like, save your favourite setup as a JSON file and share it with friends, students or your team.
Plan Your 138 Hours
Numbers that help you use the 138 hour timer in practice, all calculated for exactly 5 days and 18 hours.
When Does a 138-Hour Countdown End?
For long countdowns the weekday matters. If you start the timer on …
| Start | Timer ends |
|---|---|
| Monday 08:00 | Sunday 02:00 (6 days later) |
| Wednesday 12:00 | Tuesday 06:00 (6 days later) |
| Friday 18:00 | Thursday 12:00 (6 days later) |
| Sunday 21:00 | Saturday 15:00 (6 days later) |
Countdown Milestones
- A quarter done: after 34 hours and 30 minutes, with 4 days, 7 hours and 30 minutes remaining.
- Halfway point: after 2 days and 21 hours, with 2 days and 21 hours remaining.
- Three quarters done: after 4 days, 7 hours and 30 minutes, with 34 hours and 30 minutes remaining.
- Last 10 percent: after 5 days, 4 hours and 12 minutes, with 13 hours and 48 minutes remaining.
For long countdowns, checking in at these points helps you see whether you are on schedule.
Intervals That Fit Into 138 Hours
- Days: 5 full days and 18 hours.
- Sleep: enough time for 5 nights of 8 hours sleep, in total 40 hours of rest.
- Work: the same number of hours as 17.3 eight-hour workdays, or 3.5 full 40-hour workweeks.
138 Hours Compared With Real-World Durations
- 5.95 days: The dramatic Apollo 13 mission of April 1970 lasted 142 hours and 54 minutes. (4 hours and 54 minutes longer than this timer)
- 6 days: Building a new sourdough starter from flour and water usually takes about five to seven days. (6 hours longer than this timer)
- 6.13 days: Apollo 8, the first crewed flight around the Moon in December 1968, lasted about 147 hours. (9 hours and 42 seconds longer than this timer)
- 6.39 days: A day on Pluto lasts about 6.4 Earth days, or roughly 153 hours. (15 hours and 18 minutes longer than this timer)
- 7.38 days: The Moon needs about 7.4 days to go from new moon to first quarter. (39 hours and 12 minutes longer than this timer)