Internet speeds are in megabits per second while file sizes are in megabytes, so there is an 8× conversion.
How to use the Download Time Calculator
- File size
- Connection speed
- Efficiency (overhead)
Results update as you type, and every field accepts the units shown in its menu.
How it works
Convert the file size to bits, divide by the connection speed, and allow for overhead.
Tips
- Use the figures printed on your product or its manual when you have them.
- Round quantities up so you are never short.
- Measure twice before you buy anything cut to size.
- Everything runs in your browser – try different values to compare options.
Common mistakes to avoid
- Mixing units (inches and centimetres, mAh and Ah).
- Ignoring efficiency losses and safety margins.
- Treating rules of thumb as exact.
Inputs explained
| Field | What to enter |
|---|---|
| File size | Units: GB, MB, TB, GiB |
| Connection speed | Units: Mbit/s, Gbit/s, kbit/s |
| Efficiency (overhead) | In % |
What each result means
- Download time = [File size]×8÷([Connection speed]×[Efficiency (overhead)]÷100)
- Effective speed = [Connection speed]×[Efficiency (overhead)]÷100÷8÷1e6
Formula
Time = file size (bits) ÷ (speed × efficiency)Worked example
Inputs — File size: 4 GB; Connection speed: 100 Mbit/s; Efficiency (overhead): 90 %.
Results — Download time = 5:56; Effective speed = 11.25 MB/s.
Frequently asked questions
Why is my download slower than this?
Server limits, Wi-Fi, and other devices on your network reduce speed.
What is 1 Gbps in MB/s?
About 125 MB/s before overhead.
What formula does the Download Time Calculator use?
Time = file size (bits) ÷ (speed × efficiency).