In short: to check whether your line delivers what you pay for, use Speedtest. It picked a nearby server and showed 6 ms latency and 154 Mbps average download. FAST.com has no ads and shows a download result in about 9 seconds, but it tests against Netflix servers abroad, so latency was 39 ms and download a little lower at 133 Mbps.
- ✓ Same PC · same connection · 3 alternating runs
- Tested 2026-09-29 · Seoul, South Korea
- ! Results depend on your line, time of day and Wi-Fi
We ran both sites three times each, alternating, on the same computer and internet connection, logged out and with default settings. The numbers below are averages of three runs.
Results (average of 3 runs)
| Tool | Download | Upload | Latency (idle) | Latency (while downloading) | Test server | Ads |
|---|---|---|---|---|---|---|
| Speedtest by Ookla | 154.4 Mbps | 244.5 Mbps | 6 ms | 134 ms | Local (in Korea) | Yes |
| FAST.com | 133.3 Mbps | 303.3 Mbps | 39 ms | 408 ms | Abroad (Hong Kong, Tokyo, US) | No |
Each run
| Run | Speedtest down/up | FAST.com down/up |
|---|---|---|
| 1 | 157.4 / 240.5 | 130 / 360 |
| 2 | 153.0 / 243.1 | 140 / 260 |
| 3 | 152.8 / 250.1 | 130 / 290 |
Why the numbers differ
- Different server locations. Speedtest picked a nearby server; FAST.com measures against Netflix servers, which were in Hong Kong, Tokyo and the US this time. That is why FAST.com shows higher latency.
- Different purpose. Speedtest is closer to “how fast is my line”, FAST.com to “how fast is it when streaming from abroad”. If overseas sites feel slow, the FAST.com result is more useful.
- Upload was higher on FAST.com. The two sites measure upload differently and use different servers; it does not mean either one is wrong.
Which one to use
- Before calling your ISP about speed: Speedtest. You get a local-server result and a result ID to compare.
- A quick check with no ads: FAST.com. It starts on its own and shows download speed in 9–15 seconds.
- When games or video calls lag: look at “latency while downloading” on either site. If it jumps far above idle latency, check your router and other devices on the network.
How we tested
- Same Windows PC, Chromium-based browser and connection on 2026-09-29, alternating Speedtest and FAST.com three times each.
- Speedtest was started with the GO button, with the automatically chosen server. Each run creates a result ID.
- FAST.com starts automatically; we waited for upload and latency to finish. Download showed in 9–15 seconds and the full test took about 30 seconds.
- This is one connection in one place, so your numbers will differ. Use it to understand why results differ rather than as a ranking.
Left out
Benchbee, a Korean speed test, was left out: its old domain (benchbee.co.kr) now points to an unrelated VPN affiliate blog, and the real test page (speed.benchbee.kr) has no HTTPS and needs you to agree to data collection and choose your ISP and region first.
Tested 2026-09-29 · Results vary by connection and time of day. Got different results? Let us know.