Download / Upload Time Calculator
Estimate how long it takes to transfer a file of a given size over a connection of a given speed, accounting for real-world overhead.
Runs locally in your browser
Accounts for protocol overhead and congestion.
Mbps means megabits per second; MB/s means megabytes per second. 1 MB/s = 8 Mbps.
Assuming 90% effective throughput. Real transfers vary with disk speed, latency, and network contention.
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What is the Download / Upload Time Calculator?
This tool estimates transfer time from a file size and a connection speed, and shows the effect of protocol and real-world overhead.
How to use it
- 1Enter the file size and unit.
- 2Enter the connection speed and unit (note bits vs bytes).
- 3Optionally set an efficiency factor.
- 4Read the estimated transfer time.
How it works
Time = file size in bits / (speed in bits × efficiency). The tool handles the bit/byte conversion (1 byte = 8 bits) that trips up most manual estimates.
Limitations & notes
- Real throughput rarely equals the advertised link rate; 70–90% efficiency is typical.
- Latency, congestion and disk speed can dominate for small files.
Frequently asked questions
How long does it take to download 50 GB on a 100 Mbps connection?
In theory 50 GB is 400 billion bits, which at 100 Mbps takes 4,000 seconds, about 1 hour 7 minutes. At a realistic 90% efficiency it is about 1 hour 14 minutes. On a 1 Gbps connection the same download takes about 7 minutes 24 seconds at 90%, if the server and your storage can keep up.
What is the difference between Mbps and MB/s?
Mbps is megabits per second, the unit internet providers advertise. MB/s is megabytes per second, which download managers and game launchers usually show. One byte is 8 bits, so a 400 Mbps plan peaks at about 50 MB/s. If a launcher shows 45 MB/s on that plan, you are getting roughly 90% of the advertised speed.
Why is my upload so much slower than my download?
Most cable, DSL and many fixed wireless plans are asymmetric. A plan advertised as 300 Mbps download may offer only 10 to 35 Mbps upload. To estimate a cloud backup or video upload, enter your upload speed rather than the headline figure. Uploading 20 GB at 20 Mbps and 90% efficiency takes about 2 hours 28 minutes.
What efficiency percentage should I use?
For a large file from a fast server over a wired connection, 90 to 95% is realistic, since TCP and IP headers take a few percent. Wi-Fi often delivers 50 to 70% of the link rate. Use lower values for busy networks, VPNs or distant servers. The tool shows both the adjusted time and the theoretical minimum at 100% so you can see the range.
Does this calculator account for GB versus GiB?
Yes. The size menu offers decimal MB, GB and TB and binary MiB, GiB and TiB, and converts each to bytes before calculating. This matters for large files: 100 GiB is about 107.4 GB, so it takes about 7% longer than 100 GB. Speeds can be entered in Mbps, Gbps or MB/s.
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