Pick any time of day and watch a live countdown tick toward it, second by second. Waiting for school to let out at 3, the workday to end at 5, or midnight to arrive — the countdown shows hours, minutes, and seconds, plus decimal hours for timesheets. If the time has already passed today, it counts to tomorrow automatically.
📌 Runs live off your device’s clock and updates every second. A time that has already passed today automatically counts down to the same time tomorrow.
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How the countdown works
Every second, the calculator takes your device’s current time and subtracts it from the target time. If the target is still ahead today, that difference is the countdown; if it already passed, 24 hours are added and the countdown points at tomorrow.
remaining = target − now (+ 24 h if target ≤ now)
Worked example: at 1:23:45 PM the countdown to 5:00 PM shows 3 h 36 min 15 s. As a decimal that is 3 + 36/60 + 15/3600 = 3.60 hours — the format payroll and billing systems expect. Counting days instead of hours? The days from today calculator projects calendar dates forward, and the age calculator counts time in the other direction.
Frequently asked questions
The countdown automatically rolls over to that time tomorrow. If it is 4:30 PM and you ask how long until 3:00 PM, the calculator counts the 22 hours 30 minutes until 3:00 PM tomorrow — and labels the result "tomorrow" so there is no confusion. A time later today counts down to today.
Your device's own clock. The countdown runs entirely in your browser using the same time your phone or computer shows, so there is no timezone setting to get wrong. If you want a countdown to a time in another timezone, convert it to your local time first (3 PM Eastern is 12 PM Pacific) and enter that.
Because timesheets, payroll systems, and billing software usually want hours as decimals: 1 hour 45 minutes is 1.75 hours, not 1:45. The countdown shows both formats side by side, so if your shift ends at 5:00 PM you can read off exactly how many billable decimal hours remain without dividing minutes by 60 in your head.
Yes — it updates every second while the page is open. Browsers may slow background-tab timers to save battery, so after returning to the tab the display corrects itself immediately on the next tick, because each update recalculates from your device clock rather than counting down blindly.
Cite this calculator
APACalcBrew. (2026). How Long Until. https://calcbrew.com/how-long-until
MLA“How Long Until.” CalcBrew, 2026, calcbrew.com/how-long-until.
Link to https://calcbrew.com/how-long-until. Results are estimates; cite the underlying formula or data source for academic work.