Coding & Dev
Download Time Calculator
Calculate how long it takes to transfer files at a given network speed.
Understanding file transfer time is essential for planning software deployments, estimating user wait times, and sizing infrastructure. This calculator handles any combination of file size and network speed.
Transfer Time
40.0 sec
- speed Effective
- 100 Mbps
- file Size M B
- 500.0 MB
- theoretical
- At 100% efficiency — real-world typically 50-80% of rated speed
Formula and method
Time = (File Size in Megabits) / Speed (Mbps)
1 byte = 8 bits. File size converted to megabits, divided by speed in megabits per second.
Worked examples
Deploy 1GB Docker image on 1Gbps
- File Size:
- 1
- File Size Unit:
- Gigabytes (GB)
- Network Speed:
- 1
- Speed Unit:
- Gbps
Transfer Time: 8.0 sec
Home user downloading 4K movie
- File Size:
- 50
- File Size Unit:
- Gigabytes (GB)
- Network Speed:
- 100
- Speed Unit:
- Mbps
Transfer Time: 1.14 hours
Assumptions and limits
- Constant speed throughout transfer
- No overhead or protocol inefficiency
This tool provides an educational estimate. Rules, rates and personal circumstances can change the answer. Review the assumptions before relying on a result. Report a correction.
Common mistakes to avoid
- Confusing Mbps (megabits) with MB/s (megabytes) — ISP speeds are in bits, file sizes in bytes. 8× difference.
- Using theoretical max speed — real-world transfer is typically 50-80% of rated speed due to protocol overhead, congestion, and latency.
Frequently asked questions
Why is my 100Mbps internet slow for file downloads?
100 Mbps = 12.5 MB/s (divide by 8 to convert bits to bytes). A 1GB file should take about 80 seconds at 100Mbps. If it's slower, you may have Wi-Fi overhead, server-side limits, or contention on your ISP's network.