Files & Networking
File Transfer Time Calculator
Enter a file size and your connection speed to estimate transfer time. Add an overhead factor for a realistic figure (networks rarely hit 100% of the rated speed).
How transfer time is calculated
At its core, transfer time is just file size divided by speed — once both are in the same units. The catch is the bits-vs-bytes trap: connection speeds are sold in bits per second while files are measured in bytes. Eight bits make a byte, so a 100 Mbps line tops out at 12.5 MB/s.
time = file size ÷ (speed × overhead)
Why the overhead factor matters
No connection delivers 100% of its rated speed to a single transfer. Realistic efficiency is usually 60–90% after protocol overhead, Wi-Fi loss and server throttling. Setting an overhead factor turns an optimistic "best case" into a number you can actually plan around.
How to use this calculator
- Enter the file size and unit.
- Enter your speed in Mbps or MB/s.
- Set a realistic overhead factor.
- Read the estimated transfer time.
See more files & networking tools.
Frequently asked questions
Why is the real transfer slower than this?
Rated speeds are theoretical maximums. Protocol overhead, disk speed, Wi‑Fi and congestion typically cut throughput to 60–90%. Use the overhead slider to model this.
Mbps vs MB/s — what's the difference?
8 megabits (Mb) = 1 megabyte (MB). A 100 Mbps line moves at most 12.5 MB/s. The calculator handles the conversion for you.
Why is my real download slower than advertised?
Rated speeds are theoretical maximums. Protocol overhead, Wi-Fi, disk speed, server limits and congestion typically cut real throughput to 60–90%. Use the overhead factor to model this.
What's the difference between Mbps and MB/s?
8 megabits (Mb) = 1 megabyte (MB). A 100 Mbps connection moves at most 12.5 MB/s. The calculator converts between them automatically.