Bandwidth Calculator — data rate in Mbps

How it works

Bandwidth is a data rate — how much data moves per unit time. Storage is measured in bytes (MB, GB), but network speeds are quoted in bits per second (Mbps). Since one byte is eight bits, convert the size to megabits and divide by the time:

Mbps = (8 × file size in MB) ÷ time in seconds

The factor of 8 is the only conversion needed, because a megabyte and a megabit both use the decimal million (10⁶) — a megabyte is 10⁶ bytes and a megabit is 10⁶ bits. So a file of N megabytes is 8N megabits.

Note the units: MB (megabytes, capital B) is storage, Mb or Mbps (megabits) is rate. An internet plan sold as "100 Mbps" delivers at most 100 ÷ 8 = 12.5 MB per second, before real-world overhead.

Worked example

Downloading 100 MB of photos in 80 seconds is (8 × 100) ÷ 80 = 10 Mbps. A 4 GB (4,000 MB) movie in 10 minutes (600 s) is (8 × 4000) ÷ 600 ≈ 53.3 Mbps. A small 5 MB document in 4 seconds is 10 Mbps.

Frequently asked questions

How do I calculate bandwidth from a download?

Multiply the file size in megabytes by 8 to get megabits, then divide by the time in seconds: Mbps = (8 × MB) ÷ seconds. A 100 MB file downloaded in 80 seconds gives (8 × 100) ÷ 80 = 10 Mbps.

Why multiply by 8?

Because network speeds are measured in bits and file sizes in bytes, and one byte is eight bits. A 10 MB file is 80 megabits, so moving it in 8 seconds is a rate of 10 megabits per second. Both the megabyte and the megabit use the decimal 10⁶, so 8 is the only factor.

What is the difference between MB and Mb?

MB (megabytes) measures storage — file sizes and disk space. Mb, usually written Mbps (megabits per second), measures the rate data flows over a network. There are 8 megabits in a megabyte, so a "100 Mbps" connection transfers about 12.5 megabytes per second.

How fast should my internet be?

That depends on the task: streaming HD video needs about 5–8 Mbps, 4K around 25 Mbps, and video calls a few Mbps up and down. This calculator tells you the actual rate a past transfer achieved, which you can compare against the plan you pay for.

Does this account for overhead?

No — it gives the effective throughput of the transfer you measured, which already reflects any overhead that transfer experienced. A raw link rate is always higher than usable throughput because of protocol overhead, congestion and distance to the server.

How do I convert Mbps back to megabytes per second?

Divide the megabit rate by 8, since a byte is 8 bits. A 100 Mbps connection moves 100 ÷ 8 = 12.5 megabytes per second at best. This is the reverse of the calculation here, which multiplies megabytes by 8 to get megabits.