A packet loss test that uses real UDP
This packet loss test sends a steady stream of small UDP packets from your browser to the nearest Cloudflare edge and back, fifty a second, and counts how many return. Each packet also carries the time it left, so the same run tells you your ping and your jitter. At the end you get the three numbers, a timeline of the whole run, and a plain verdict on what the connection is good for.
The UDP part matters. Games, voice chat and video calls all send their data over UDP because it never waits for a lost packet to be resent: a late voice sample is worthless, so it is simply dropped. A test that runs over an ordinary web request uses TCP instead, and TCP quietly resends anything that goes missing. That kind of test can only ever report 0% loss, however bad your line is. Here the packets travel on a WebRTC data channel set to never retransmit, so a packet the network drops stays dropped and shows up in the count.
How to read the packet strip
The strip under the numbers draws every packet in the run from left to right. The height of each tick is how long that packet took to come back, so a flat, low strip is a healthy connection. A red mark means the packet never returned.
Where the red marks fall tells you more than the percentage. Marks scattered evenly across the run point to a constant fault, such as a damaged cable or a line that is running close to its limit. Marks bunched into one or two clumps point to something that happened at that moment: a microwave, a neighbour's wifi, somebody starting a big download. Tall ticks with no red marks are latency spikes, which feel like lag even when nothing is lost.
What your result means
For most people the answer is clear from the verdict list under the test, which rates the run separately for online gaming, voice calls, video meetings, streaming and ordinary browsing. The same connection can be fine for one and poor for another, because each use tolerates loss, ping and jitter differently. Streaming video buffers ahead and shrugs off a few percent of loss. A competitive shooter notices half a percent.
| Measure | Good | Noticeable | A problem |
|---|---|---|---|
| Packet loss | Under 0.5% | 0.5% to 2% | Over 2% |
| Ping | Under 40 ms | 40 to 100 ms | Over 150 ms |
| Jitter | Under 5 ms | 5 to 30 ms | Over 30 ms |
Why a run lasts 30 seconds
Packet loss is rarely constant. A connection can run clean for ten seconds and then drop a burst of packets when the wifi router changes channel or another device on the network starts uploading. A three-second test often misses that burst entirely, and a result of 0% from a short test only means nothing went wrong in those three seconds.
The default run sends 1,500 packets over 30 seconds, which is long enough to catch most intermittent loss and short enough to sit through. If your problem comes and goes, choose the 60-second run, or use the internet stability test, which starts at 60 seconds and counts the seconds where loss or ping spiked. At fifty packets a second of 160 bytes each, the whole test uses less than one megabyte, so it does not load your connection or change the result it is measuring.
Where the packets go
The test connects through Cloudflare's TURN relay, which runs in hundreds of cities worldwide. Your browser is routed to the nearest one automatically, so the result reflects your own connection, meaning your wifi, your router and your internet provider, rather than the distance to one far-away test server. A packet leaves your device, reaches that nearby edge, and comes straight back.
That is also the limit of what this measures. It will show loss on your side of the internet, which is where nearly all fixable loss happens. It cannot see loss on the path between your provider and a particular game server on another continent. If this test is clean and one game still drops packets, the problem is likely on that route or on the game's own servers.
What to do if you have packet loss
- Test on a cable. Plug your computer into the router with an Ethernet cable and run the test again. If the loss disappears, the cause is your wifi. See wifi or ethernet: where packet loss comes from.
- Restart the router and modem. It clears overloaded connection tables and memory leaks that build up in cheap routers, and it is free.
- Stop other traffic. Pause downloads, cloud backups and streams on other devices, then test again. A full upload is the most common cause of lag nobody notices.
- Check the cables. A worn Ethernet cable or a loose coax connector causes steady, even loss. Swap it for a known good one.
- Call your provider with the result. If loss persists on a cable with nothing else running, copy the result and send it to your ISP. A timestamped number is harder to dismiss than "my internet is laggy".
The full walk-through, from the five-minute checks to what to say to your ISP, is in how to fix packet loss.
No sign-up, nothing stored
The test runs in your browser and needs no account, app or download. Your result is calculated on your own device and is not saved anywhere; the relay only sees anonymous test packets that carry a sequence number and some padding. The short-lived relay credentials each run uses expire after five minutes.