A speed test hands you a handful of numbers and no explanation: 94 Mbps down, 31 up, 12 ms ping. Whether those are good depends on what you do online, and one of them, the ping, matters more for a video call or a game than the download speed does. This guide explains each number, how much speed everyday activities actually need, why the result is almost always lower than the plan you pay for, and how to get a reading you can trust.
A speed test moves data between your device and a test server and times it. A good one reports four things:
The first two describe how much data fits through your connection per second. The last two describe how quickly and steadily it responds. You can have a very fast connection with a poor response, and the other way round.
Internet plans are sold in megabits per second (Mbps). File downloads usually show megabytes per second (MB/s). A byte is eight bits, so the two differ by a factor of eight. This is how long a 1 GB file takes at full line speed:
| Speed in Mbps | Speed in MB/s | Time for a 1 GB file |
|---|---|---|
| 10 | 1.25 | about 13 minutes |
| 50 | 6.25 | 2 min 40 s |
| 100 | 12.5 | 1 min 20 s |
| 500 | 62.5 | 16 s |
| 1,000 | 125 | 8 s |
If your download manager shows 12 MB/s on a 100 Mbps plan, the connection is doing exactly what it should. The Download Time Calculator does this arithmetic for any file size, and the Data Usage Calculator shows how much data an activity uses over a month.
Ping is the round-trip time to a server. As a rough guide, a wired connection to a nearby server is often under 20 ms, Wi-Fi adds a few milliseconds, mobile networks commonly sit between 30 and 60 ms, and a geostationary satellite link is over 500 ms because the signal travels to orbit and back. Distance matters too: a server on another continent adds tens of milliseconds that no plan can remove.
Jitter is the average change between consecutive pings. A steady connection has a jitter of a few milliseconds. When jitter climbs into the tens of milliseconds, voice cuts out and game characters stutter even though the average ping looks fine, because the packets arrive unevenly.
Two rules of thumb, which the Internet Speed Test also uses when it rates your result:
Bufferbloat is the most common reason a "fast" connection feels slow. When something saturates your line, such as a big download or a cloud backup, the packets queue up in oversized buffers in the router or modem, and every other request waits behind them. Ping while idle might be 15 ms and ping under load 400 ms. That is why your video call freezes the moment someone starts a download. A good speed test therefore also reports latency under load, the ping measured while the line is busy. A large jump between the two is bufferbloat. The usual fix is a router with smart queue management (often called SQM, fq_codel or CAKE), set a little below your real line speed, commonly 85 to 95 per cent of it.
Streaming and calling services publish what they ask for per stream. These figures are typical, and they add up when several people use the connection at once:
| Activity | Typical need | What matters most |
|---|---|---|
| Browsing, email, messaging | about 3 Mbps | Ping |
| HD video (1080p) | about 5 Mbps per stream | Download |
| 4K video | about 25 Mbps per stream | Download |
| HD video call | about 3 Mbps each way, ping under 100 ms | Upload, ping and jitter |
| Online gaming | a few Mbps, ping under 60 ms that stays steady | Ping and jitter |
| Cloud gaming | about 25 Mbps, ping under 40 ms | Download and ping |
| Large downloads and uploads | as much as you can get | Download or upload |
Some services get 4K onto about 15 Mbps; 25 Mbps is the figure that leaves headroom. To size a household, add up what runs at the same time and leave about a quarter spare. Two 4K streams (2 × 25 Mbps) and a video call (3 Mbps) already need about 53 Mbps, so roughly 70 Mbps is a comfortable line for that evening. For most households, somewhere between 100 and 300 Mbps is plenty. Beyond that, extra speed rarely changes everyday experience; a steady low ping and good Wi-Fi do.
Plans are sold as "up to" a speed, and several things stand between the line and the number on screen:
A test like the one on ArrayKit first times a handful of tiny round trips to get ping and jitter. It then downloads test data over several connections at once, leaves out the first moments while the connection is still speeding up, and averages the steady part that follows, so a short burst cannot flatter the result. It repeats the process for upload. Several parallel connections are used because a single one often cannot fill a fast line. Each phase runs for a set time, or until it hits a data cap, which is why the amount of data a test uses grows with your speed.
The Internet Speed Test measures download, upload, ping and jitter and, on connections that can measure it, latency under load. It then rates the result for browsing, HD and 4K streaming, video calls, online gaming and cloud gaming. Pick a Quick, Standard or Extended run, read the speeds in Mbps or MB/s, and keep your last ten results in your browser to compare over a week. The test sends and receives test data to a public speed-test server, which sees your IP address as any website you visit does. None of your files or text is involved.
What is a good internet speed? For one person, about 25 Mbps handles HD streaming and video calls comfortably. A household with several people streaming at once is better served by 100 Mbps or more. For gaming and calls, a ping under about 50 ms and low jitter matter as much as the speed.
Is 100 Mbps fast? Yes, for most homes. It supports several HD streams, a few 4K streams or a video call alongside normal browsing. It becomes limiting when many devices download large files at once.
What is a good ping for gaming? Up to about 30 ms is comfortable and up to about 60 ms is fine for most games, as long as the jitter stays low too. Over 100 ms is noticeable in fast games, and a wired connection to a nearby server is the surest way to keep it down.
Why is my upload speed so much lower than my download speed? Most home broadband and mobile plans are built that way, because most people download far more than they upload. Fibre plans are the common exception and often offer the same speed in both directions.
What is the difference between ping and jitter? Ping is how long one message takes to make the round trip. Jitter is how much that time varies between messages. Low ping with high jitter still feels unreliable.
Why does my speed test result change every time? Congestion, Wi-Fi quality, other devices and the test server all change from minute to minute. Results within about 10 per cent of each other are normal; compare the middle of several runs.
Does a speed test use a lot of data? It depends on your speed, because each phase runs for a set time. On a 100 Mbps connection a Standard test moves roughly 150 to 250 MB in all, both directions together. The Internet Speed Test also stops each direction at 200 MB (Quick), 400 MB (Standard) or 800 MB (Extended), so choose Quick on mobile data.