How long is a 90 minute video at 1.5x?

1:00:00, with 0:30:00 saved. The arithmetic is the runtime divided by the multiplier: 90 minutes is 5,400 seconds, and 5,400 divided by 1.5 is 3,600. The same 90 minutes is 1:12:00 at 1.25x, 0:51:26 at 1.75x and 0:45:00 at 2x, and the three nearest player steps are worked out under the answer so you can compare them without retyping anything.

What speed do I need to finish something before a deadline?

Switch the calculator to Speed for a deadline and give it the runtime and the time you have. It inverts the same division: 1:30:00 with only 1:10:00 available needs 1.29x, which finishes in 1:09:46 and leaves 0:00:14 to spare. The unrounded requirement there is about 1.2857, and the answer is rounded up to the next hundredth on purpose: 1.28x would finish in 1:10:19, past the 1:10:00 you just typed. Each of the three nearest player steps then says whether it fits or by how much it runs over.

How much time does 2x actually save?

Exactly half the runtime, at any runtime: what takes an hour takes 0:30:00. The saving is not linear as the speed goes up, which is why the figures are worth seeing. At 1.25x an hour of runtime takes 0:48:00 and saves 0:12:00; at 1.5x it takes 0:40:00 and saves 0:20:00; at 1.75x it takes 0:34:17 and saves 0:25:43. A 10 hour audiobook at 1.75x is 5:42:51 of listening, saving 4:17:09.

Can I add up a whole playlist or a podcast queue?

Yes. Put every length in the runtime field separated by commas, semicolons, plus signs or new lines, and a column of clock times pasted straight in works too. The lengths are summed first and the multiplier is applied to the total, which is the order the accuracy line states: 12:30 and 8:05 total 0:20:35, which is 0:13:43 at 1.5x. Up to 500 items are totalled at once, and the first 100 are listed underneath with their own time at the speed you chose.

Does 1:30 mean ninety seconds or an hour and a half?

Here it means ninety seconds. Two colon parts are read as minutes and seconds, the way a player writes them, and three parts as hours, minutes and seconds. For an hour and a half write 1:30:00, 1h30m or 90. Whatever you write, the dark panel repeats the length it was read as, so an ambiguous entry is visible immediately instead of quietly changing the answer.

What is the fastest and slowest speed it will take?

Anything from 0.01x to 100x, entered as 1.5, 1.5x or 150%. A speed of 0 is refused, because nothing ever finishes at it, and so is a negative speed. The range is deliberately wider than any player: many players stop at 2x or 3x, and this page cannot know what your player allows, so it answers for the number you typed and leaves the cap to the app.

Does it work for slowing something down?

Yes, and it says so rather than reporting a negative saving. Below 1x the fourth cell changes from Saved to Added: an hour at 0.75x becomes 1:20:00, which is 0:20:00 added rather than saved. That is the speed people use for transcription and for language practice, and the arithmetic is identical, just on the other side of 1.

Does anything I type here leave my browser?

No. The arithmetic runs in the page, there is no account and nothing is uploaded or reported anywhere. Your last runtime, speed and deadline are kept in this browser so they are still there after a reload, and if storage is blocked the calculator still works, it simply opens on the worked example each time.

Playback Speed Calculator

A 1:30:00 lecture at 1.5x is 1:00:00, with 0:30:00 handed back, and at 2x it is 0:45:00. This calculator does that division both ways from the same four cells. Give it a runtime and a speed and it answers with the time at that speed and the time saved, so an hour at 1.5x takes 0:40:00 and gives back 0:20:00, while 0.75x for a language lesson stretches that hour out to 1:20:00. Give it a runtime and the time you actually have and it inverts the same relation to solve the speed: 1:30:00 inside 1:10:00 needs 1.29x, which finishes in 1:09:46 with 0:00:14 to spare, and the rounding always goes upwards so the hundredth you type into the player is still enough. Runtimes read the way people write them, as 1:30:00, 90m, 1h30, 90 minutes or a bare 90 for minutes, and the length each one was read as goes back on the dark panel, so a misread is visible at a glance rather than hidden inside the answer. A playlist goes into the same field, separated by commas or pasted as a column: 12:30 and 8:05 total 0:20:35, which is 0:13:43 at 1.5x, and both episodes are listed underneath with their own time at that speed.

At 1.5x1:00:00runtime 1:30:00 · saves 0:30:00 · 1 item

Runtime

Speed

At speed1:00:00

Saved0:30:00

1:30:00 ÷ 1.5 = 1:00:00. At 1.5x every hour of runtime takes 0:40:00 and saves 0:20:00. Two colon parts are minutes and seconds, the way a player writes them, so 1:30 is ninety seconds and 1:30:00 is an hour and a half. A bare number is minutes. Times are shown to the nearest second and speeds to four decimals, and the speed a deadline needs is rounded up to the next hundredth so the number you type still fits.

The same runtime at other speeds

The three nearest steps a player offers, worked out from whatever is in the runtime above. Copy any row on its own.

At 1.25xruntime ÷ 1.25
1:12:00, saves 0:18:00
At 1.75xruntime ÷ 1.75
0:51:26, saves 0:38:34
At 2xruntime ÷ 2
0:45:00, saves 0:45:00

Accuracy. Exact arithmetic: runtime divided by the speed multiplier, and the same relation inverted to find the speed a deadline needs. A playlist is summed before the multiplier is applied. It assumes you play straight through, so it cannot know about pauses, ads, or a player that caps its own speed lower than the number you typed.

Common questions

How long is a 90 minute video at 1.5x?: 1:00:00, with 0:30:00 saved. The arithmetic is the runtime divided by the multiplier: 90 minutes is 5,400 seconds, and 5,400 divided by 1.5 is 3,600. The same 90 minutes is 1:12:00 at 1.25x, 0:51:26 at 1.75x and 0:45:00 at 2x, and the three nearest player steps are worked out under the answer so you can compare them without retyping anything.
What speed do I need to finish something before a deadline?: Switch the calculator to Speed for a deadline and give it the runtime and the time you have. It inverts the same division: 1:30:00 with only 1:10:00 available needs 1.29x, which finishes in 1:09:46 and leaves 0:00:14 to spare. The unrounded requirement there is about 1.2857, and the answer is rounded up to the next hundredth on purpose: 1.28x would finish in 1:10:19, past the 1:10:00 you just typed. Each of the three nearest player steps then says whether it fits or by how much it runs over.
How much time does 2x actually save?: Exactly half the runtime, at any runtime: what takes an hour takes 0:30:00. The saving is not linear as the speed goes up, which is why the figures are worth seeing. At 1.25x an hour of runtime takes 0:48:00 and saves 0:12:00; at 1.5x it takes 0:40:00 and saves 0:20:00; at 1.75x it takes 0:34:17 and saves 0:25:43. A 10 hour audiobook at 1.75x is 5:42:51 of listening, saving 4:17:09.
Can I add up a whole playlist or a podcast queue?: Yes. Put every length in the runtime field separated by commas, semicolons, plus signs or new lines, and a column of clock times pasted straight in works too. The lengths are summed first and the multiplier is applied to the total, which is the order the accuracy line states: 12:30 and 8:05 total 0:20:35, which is 0:13:43 at 1.5x. Up to 500 items are totalled at once, and the first 100 are listed underneath with their own time at the speed you chose.
Does 1:30 mean ninety seconds or an hour and a half?: Here it means ninety seconds. Two colon parts are read as minutes and seconds, the way a player writes them, and three parts as hours, minutes and seconds. For an hour and a half write 1:30:00, 1h30m or 90. Whatever you write, the dark panel repeats the length it was read as, so an ambiguous entry is visible immediately instead of quietly changing the answer.
What is the fastest and slowest speed it will take?: Anything from 0.01x to 100x, entered as 1.5, 1.5x or 150%. A speed of 0 is refused, because nothing ever finishes at it, and so is a negative speed. The range is deliberately wider than any player: many players stop at 2x or 3x, and this page cannot know what your player allows, so it answers for the number you typed and leaves the cap to the app.
Does it work for slowing something down?: Yes, and it says so rather than reporting a negative saving. Below 1x the fourth cell changes from Saved to Added: an hour at 0.75x becomes 1:20:00, which is 0:20:00 added rather than saved. That is the speed people use for transcription and for language practice, and the arithmetic is identical, just on the other side of 1.
Does anything I type here leave my browser?: No. The arithmetic runs in the page, there is no account and nothing is uploaded or reported anywhere. Your last runtime, speed and deadline are kept in this browser so they are still there after a reload, and if storage is blocked the calculator still works, it simply opens on the worked example each time.

Exact arithmetic: runtime divided by the speed multiplier, and the same relation inverted to find the speed a deadline needs. A playlist is summed before the multiplier is applied. It assumes you play straight through, so it cannot know about pauses, ads, or a player that caps its own speed lower than the number you typed.