Calculate CD burn time, burn speed, or total data size by entering any two values with units from bytes to terabytes and seconds to hours.
Cd Burn Time Formula
The basic relationship is data size, burn speed, and burn time. The calculator converts the entered units to megabytes and seconds, performs the calculation, then converts the answer back to the unit you selected.
T = S / R
R = S / T
S = R * T
- T = burn time
- S = total data size
- R = burn speed, or write rate
If you enter total data size and burn speed, the calculator finds burn time with T = S / R.
If you enter total data size and burn time, it finds the required burn speed with R = S / T.
If you enter burn speed and burn time, it finds the amount of data that can be written with S = R * T.
Common CD Capacities and Write Speeds
These values can help you choose realistic inputs. The burn time is the ideal data-writing time only and does not include lead-in, lead-out, disc finalization, verification, or drive slowdown.
| CD type | Typical capacity | Use in calculator |
|---|---|---|
| 74-minute CD-R | 650 MB | Enter 650 MB |
| 80-minute CD-R | 700 MB | Enter 700 MB |
| 90-minute CD-R | 800 MB | Enter 800 MB |
| CD write speed | Approx. data rate | Ideal time for 700 MB |
|---|---|---|
| 4x | 0.60 MB/s | 1166.67 s, or 19.44 min |
| 8x | 1.20 MB/s | 583.33 s, or 9.72 min |
| 16x | 2.40 MB/s | 291.67 s, or 4.86 min |
| 24x | 3.60 MB/s | 194.44 s, or 3.24 min |
| 48x | 7.20 MB/s | 97.22 s, or 1.62 min |
| 52x | 7.80 MB/s | 89.74 s, or 1.50 min |
Example Problems
Example 1: Find burn time
You want to burn 700 MB at 7.80 MB/s.
T = 700 / 7.80 = 89.74 seconds
The ideal burn time is 89.74 seconds, or about 1.50 minutes.
Example 2: Find data size
You burn at 2.40 MB/s for 300 seconds.
S = 2.40 * 300 = 720 MB
The amount of data written is 720 MB.
FAQ
Why is the actual CD burn time longer than the calculated time?
The result is based only on data size divided by burn speed. Real CD burning also includes preparation, lead-in writing, lead-out writing, finalization, possible verification, and speed changes during the burn. These steps can add extra time.
What burn speed should I enter for 48x or 52x CD burning?
A CD drive’s 1x speed is about 150 KB/s, or 0.15 MB/s. For 48x, enter about 7.20 MB/s. For 52x, enter about 7.80 MB/s. Actual speed may be lower if the drive starts slowly and ramps up during the burn.
Does the calculator use decimal or binary storage units?
It uses decimal units: 1 KB = 1,000 bytes, 1 MB = 1,000 KB, and 1 GB = 1,000 MB. This matches the unit conversions used by the calculator and is common for disc capacity labels.
