How download speed is measured
The test asks Cloudflare’s servers for files of increasing size, starting at 100 KB and stepping up to as much as 250 MB per request. It times each transfer using your browser’s own timing data, then works out the speed from the size and duration.
Small files finish too quickly to show a fast connection’s full speed, so the test keeps moving to larger files until each transfer takes long enough to be meaningful. The reported number is a high percentile (the 90th) of the measured transfers. That reflects what your connection can sustain, without letting one slow request drag the number down or one lucky burst inflate it.
The full details are on the methodology page.
Mbps, MB/s and download times
Speed tests report megabits per second (Mbps). Game stores, browsers and download managers often show megabytes per second (MB/s). There are 8 bits in a byte, so divide Mbps by 8 to get MB/s.
| Speed | MB/s | 1 GB file | 50 GB game |
|---|---|---|---|
| 25 Mbps | 3.1 | 5 min 20 s | 4.4 hours |
| 100 Mbps | 12.5 | 1 min 20 s | 67 min |
| 300 Mbps | 37.5 | 27 s | 22 min |
| 1 Gbps | 125 | 8 s | 6.7 min |
Real downloads are often slower than the table, because the server you are downloading from may be busy or far away, or may limit each download.
How much download speed you need
Start from what the services say they need, then add up what happens at the same time in your home:
- HD (1080p) video: 5 Mbps per stream (Netflix and YouTube).
- 4K video: 15 Mbps per stream (Netflix) to 20 Mbps (YouTube).
- Browsing, email, social media: a few Mbps, though pages feel snappier with more.
- Large downloads: no fixed requirement; more speed simply means shorter waits.
Three people each watching 4K at once need roughly 45–60 Mbps for the video alone. Our guide to what counts as a good internet speed shows how to size this for your household.
Why your download result might be low
- You are on WiFi far from the router. Compare with a WiFi test near the router or a wired test.
- Another device is downloading, streaming or updating.
- It is a busy time on your provider’s network.
- Your device, browser or VPN is limiting the result.
Work through the causes in our guide to fixing slow internet.