Download Time Calculator
Estimate how long a download will take from file size and your internet connection speed in Mbps, free right in your browser.
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Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the file size in MB and your speed in Mbps.
- Press Calculate for the download time.
How it works
File size is in bytes but speed is in bits, and there are 8 bits in a byte, so time (seconds) = file size (MB) × 8 ÷ speed (Mbps).
Worked example
100 MB at 8 Mbps. 100 × 8 ÷ 8 = 100 seconds.
Common mistakes
- Mixing megabits and megabytes — divide your Mbps speed by 8 to get MB/s before estimating time.
- Using the plan's headline speed; real throughput is usually lower from overhead and congestion.
Frequently asked questions
How is download time calculated?
Time = file size ÷ speed, with units matched. A 5,000 MB file on a 100 Mbps line (12.5 MB/s) takes about 400 seconds, under 7 minutes, ignoring overhead.
Why is my real download slower?
Protocol overhead, server limits, Wi-Fi and congestion all cut into the headline speed, so allow extra time over the theoretical figure.
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Cite this tool
Zerdly. (2026). Download Time Calculator. Retrieved from https://www.zerdly.com/tools/download-time-calculator/
Tip: Enter any known values to calculate the remaining results.
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