Download time calculator

How long a file takes to transfer at a given connection speed.

Formula Digital data

Time (h:mm:ss)

Seconds: 4,000.00 s
Minutes: ≈ 66.67 min
Hours: ≈ 1.111 h

How it works

Internet speeds are quoted in bits per second, while file sizes are in bytes. One byte is 8 bits, so the size in bytes is multiplied by 8 and divided by the speed.

Storage units come in two families: decimal (1 GB = 1,000,000,000 bytes) and binary (1 GiB = 1,073,741,824 bytes). Operating systems often show binary sizes labelled “GB”, so check which one you have.

The result is the best case at the full speed you enter. The overhead allowance reduces the speed to account for protocol headers, Wi-Fi and server limits.

Formula

Time (s) = size (bytes) × 8 ÷ (speed (bit/s) × (1 − overhead))

Worked example

A 50 GB file at 100 Mbit/s takes 50 × 10⁹ × 8 ÷ (100 × 10⁶) = 4,000 seconds, which is 1:06:40. With a 10% overhead allowance it takes about 1:14:04.

Questions people ask

What is the difference between Mbps and MB/s?

Mbps (Mbit/s) is megabits per second; MB/s is megabytes per second. 100 Mbit/s is 12.5 MB/s, because a byte is 8 bits.

Why is my download slower than this?

Protocol overhead, Wi-Fi, other devices on the network and the server’s own limits all reduce the real speed.