How Internet Speed Tests Actually Work
A speed test moves a known amount of data and times it. Download the test file, count the megabytes, divide by seconds, convert to bits, that number in megabits per second is what you see.
Why your numbers jump around
A few things skew results:
- Wi-Fi vs ethernet, wireless adds interference and overhead
- Other devices, streaming on one TV can halve another device’s reading
- Server distance, a test endpoint far from you adds latency
- Time of day, ISP congestion peaks in the evening
For a cleaner number, plug in over ethernet, pause downloads, and run the speed test a few times at different hours.
What “good” looks like
- Streaming HD video: around 5–10 Mbps per stream
- Video calls: 3–5 Mbps up and down
- A household of four: 100 Mbps down feels comfortable
Related tools
Run the speed test, and if results look off, read why downloads can crawl despite 100 Mbps.
Further reading
How tests measure your connection
- A small ping measures how long a tiny request takes to reach the server and come back.
- A download test pulls a known chunk of data and times it. Larger and steadier transfers give a more stable number.
- An upload test does the same in the other direction.
Most modern tests run several short transfers and average them, which smooths out dips from Wi-Fi interference or a busy network.
Factors that quietly change your result
- The distance and load of the test server
- Whether you test on Wi-Fi or Ethernet
- Background updates, cloud sync, or streaming on other devices
- Time of day, especially on shared cable networks
- The plan you pay for, since upload is often much lower than download
FAQ
What is a good download speed?
For one or two people, 25 to 100 Mbps is comfortable. Families with 4K streaming and remote work often want 100 to 300 Mbps.
What is a good upload speed?
For normal use, 10 to 20 Mbps is fine. Content creators and remote teams that upload large files benefit from 50 Mbps or more.
What is a good ping?
Under 50 ms feels instant. 50 to 100 ms is acceptable. Above 150 ms, online games and calls start to feel laggy.
Why do results differ between test sites?
Each site uses different servers, different file sizes, and different averaging. Our tool uses a real transfer you can watch live, while others average several runs. Both approaches are valid.