Online Lecture Playback Speed Calculator
Add up online lecture durations and calculate watch time and time saved at 1.25×, 1.5×, and 2× speed. Calculate up to 300 lectures for free.
Applying this will replace the course list and speed of this tool. Date settings remain unchanged, and existing plans are recalculated.
My viewing time
First step of the plan: start with small calculations.
Enter the lecture time and calculate it.
It’s okay to first examine the example.
Share result
Share the tool link and result text together. No URL is included in the result. Check the below content and then share it.
Store my data
It can be used continuously in the same browser. If browser data is deleted, the record may disappear.
How is the calculation performed?
Watch time equals the total original lecture duration divided by playback speed. A 60-minute lecture takes 40 minutes at 1.5× speed. This calculator adds up watch time and time saved across multiple lectures.
Savings time = original time − viewing time
Listening to a 60-minute lecture at 1.5x speed takes 40 minutes and saves 20 minutes. If I listen to 45 minutes and 30-minute lectures at 1.25x speed, it takes 60 minutes total. If I listen slower than 1x speed, the additional time is displayed.
Things to note when calculating
Supports up to 300 lectures, each from 1 second to 24 hours. Set playback speed from 0.5× to 3.0×. Titles are optional and limited to 100 characters. Intermediate values are not rounded; only the final result is rounded up to the next second. For example, 3 lectures of 1 second each at 2× take 1.5 seconds, displayed as 2 seconds.
This calculates playback time only; it excludes note-taking, review, and pauses. Use the course completion planner to account for your actual study time.
Frequently Asked Questions
How many minutes is a 1.5x or 2x speed lecture for 1 hour?
1.5x speed is 60 ÷ 1.5 = 40 minutes; 2x speed is 60 ÷ 2 = 30 minutes. Each reduces the original time by 20 minutes and 30 minutes respectively. Writing and pause times are not included.
How are 1:30 and 90:00 entered?
1:30 is 1 minute and 30 seconds, and 90:00 is 90 minutes. Even if 90 is entered, it is interpreted as 90 minutes. For 1 hour and 30 minutes, enter 90 or 1:30:00.
How do you sum the durations of multiple lectures?
Enter the length of each lecture on a separate line, or enter one per line in the time input field. First, sum the original times of up to 300 lectures, then apply a common speed. Incorrect lines indicate the location and cause.
How are results with a decimal point and exceeding 24 hours displayed?
Intermediate calculations are not rounded; only the final time is displayed in seconds. If 3 lessons of 1 second are played at 2x speed, the actual 1.5 second is displayed as 2 seconds. The total time exceeds 24 hours, but the sum remains unchanged.
Can study time including writing·review also be calculated?
This tool calculates playback time only. Send the lecture list to the course completion planner to calculate daily study time based on your extra-time percentage and available study dates.
Calculation criteria and reference materials
The calculation formula and scope of this tool are disclosed in the above description. Examples can be checked by substituting input values into the formula or following the specified string and calendar handling rules.
Verification of calculation criteria: · Calculation·verification principles · Report errors