How to read a speed test: download, upload, ping and jitter

You just ran a speed test and four numbers appeared. What do they mean, and above all, is your connection good? This guide shows you how to read each value, compare it with your plan and turn it into a useful diagnosis.

The four values of a speed test

Download: the number everyone looks at

Download speed is how much data your connection can receive each second. It sets how fast pages load, the highest video quality you can stream and how long downloads take. It is measured in megabits per second (Mbps); do not confuse it with the megabytes per second your browser shows, see Mbps vs MB/s.

How to judge it: compare it with your plan. Over an Ethernet cable, a healthy fibre line usually delivers more than 90% of the subscribed speed. Over Wi-Fi, a 20 to 50% loss is common depending on distance and walls.

Upload: often forgotten, yet essential

Upload measures how fast you send data. It drives the quality of your image in video calls, sending photos on WhatsApp, cloud backups and live streaming. On ADSL, upload rarely exceeds 1 Mbps, which explains pixelated video calls. Fibre changes that. More in why upload speed matters.

Ping: how responsive your connection is

Ping, or latency, is the time in milliseconds a small packet takes to go from your device to the server and back. The lower it is, the snappier the connection. It depends on the technology (fibre, ADSL, 4G), your home network and the distance to the server.

• Under 20 ms: excellent.
• 20 to 50 ms: very good for gaming and video calls.
• 50 to 100 ms: fine for browsing and video.
• Over 100 ms: noticeable lag.

Jitter: stability

Jitter measures how much ping varies from one packet to the next. An average ping of 30 ms with 2 ms of jitter is excellent; the same ping with 40 ms of jitter will cause call drop-outs and "teleporting" in games. Congested Wi-Fi is the most common cause of high jitter. Everything is covered in ping, latency and jitter explained.

Interpreting your result in 4 steps

1. Compare download with your plan by entering your plan speed in the result: the percentage appears.
2. Test again over a cable: if the result becomes good, the problem is Wi-Fi.
3. Test at different times: a systematic evening drop points to peak-hour congestion.
4. Look at ping and jitter: good speed with high jitter means an unstable home network.

Measure your connection now. Start the test

The most common reading mistakes

• Comparing a Wi-Fi test with your plan: like measuring water pressure at the end of a leaking hose.
• Testing during a download: a background update can halve the result.
• Trusting a single test: keep the middle value of three.
• Forgetting device limits: an old phone or a 100 Mbps Ethernet port tops out around 94 Mbps even on a 1 Gbps line.

And if the result is poor?

Start with slow internet: causes and fixes. If your fibre is fast on cable but slow on Wi-Fi, read why Wi-Fi slows down fibre.

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Frequently asked questions

The SpeedFibre team Guides written and reviewed by a telecom engineer specialised in fibre optics (FTTH), with more than 8 years of hands-on network maintenance and measurement. Editorial policy.