Data Transfer Time Calculator
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
Enter Values
How to use this calculator
- Enter the file size in MB (1 GB = 1000 MB).
- Enter your connection speed in Mbps.
- Read the estimated transfer time.
How it works
The Data Transfer Time Calculator estimates how long a download or upload takes from the file size and the link speed. The catch most people miss: file sizes are in bytes (MB) but speeds are in bits (Mbps), and there are 8 bits in a byte.
Time (seconds) = file size in MB × 8 ÷ speed in Mbps. The result is a theoretical best case; real transfers run 10–30% slower because of protocol overhead, network contention and disk speed.
Worked example
A 1.5 GB file on a 100 Mbps line. 1500 MB × 8 ÷ 100 = 120 seconds (2 minutes) at best.
Frequently asked questions
Why isn't 100 Mbps the same as 100 MB per second?
Speeds are quoted in megabits (Mbps) but files are measured in megabytes (MB), and a byte is 8 bits. So 100 Mbps is about 12.5 MB per second, not 100.
Why is my real download slower?
Overhead, shared bandwidth, server limits and your disk all add up. A 10–30% margin over the theoretical time is typical.
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Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.