Download Time Calculator

Estimate how long a file takes to download or upload.

Estimated transfer time

1 min 32 sec

1.00 GB at 12.50 MB/s

Theoretical minimum

1 min 20 sec

Effective speed

12.50 MB/s

File size in bytes

1,000,000,000

Speed in megabits

100.0 Mbps

Time = file size in bytes ÷ (speed in bits ÷ 8). Megabits divide by 8 to give megabytes.

Providers quote megabits and file sizes are in megabytes — a 100 Mbps connection delivers about 12.5 MB/s at best. That factor of eight is the usual reason a download feels slower than expected.
Real transfers also lose speed to protocol overhead, server limits, Wi-Fi contention and shared bandwidth.

The same file across common connection speeds.
Connection	Speed	Estimated time
ADSL (8 Mbps)	1.0 MB/s	19 min 10 sec
Basic broadband (25 Mbps)	3.1 MB/s	6 min 8 sec
Standard fibre (100 Mbps)	12.5 MB/s	1 min 32 sec
Fast fibre (500 Mbps)	62.5 MB/s	18 seconds
Gigabit (1000 Mbps)	125.0 MB/s	9 seconds
4G average (25 Mbps)	3.1 MB/s	6 min 8 sec
5G average (150 Mbps)	18.8 MB/s	1 min 1 sec

What does Download Time Calculator do?

Estimate transfer time from file size and connection speed, with the bits-versus-bytes conversion handled correctly — the single most common reason people think their connection is underperforming.

How to Use Download Time Calculator

1
Enter the file sizeAnd pick its unit.
2
Enter your connection speedUsually quoted in Mbps.
3
Read the estimateBoth theoretical and with overhead.

Key Features

File size in any unit, from KB to TB
Speed in Mbps, MB/s or any other rate unit
Correct bits-to-bytes conversion, shown explicitly
Optional protocol overhead allowance for a realistic estimate
Comparison table across common connection speeds
Reverse mode: the speed needed to finish in a target time

Frequently Asked Questions

Why is my download slower than my connection speed?

Mostly the bits-and-bytes confusion: a 100 Mbps connection delivers about 12.5 MB/s at absolute best. On top of that, protocol overhead, server limits, Wi-Fi contention and shared bandwidth typically cost another 10–20%.

What is the difference between Mbps and MB/s?

Mbps is megabits per second, MB/s is megabytes per second. Divide Mbps by 8 to get MB/s. Internet providers quote bits because the number is eight times larger.

How long does a 1 GB file take?

At 100 Mbps, about 80 seconds theoretically and closer to 95 with overhead. At 10 Mbps it is around 13 minutes. The comparison table covers common speeds.

Does upload speed differ from download?

Usually yes. Most residential connections are asymmetric, with upload often a fifth of download or less. Check your actual upload figure when estimating backup or file-sharing times.

Runs in your browser

This is a pure calculation performed in your browser. No connection test is run and no data is transmitted.

How the rest of the site handles data