Bufferbloat test. Ping, with the line busy.
Bufferbloat is latency that climbs when the connection is busy: a router queues more data than it should, and every game packet and call waits behind it. This test measures ping on an idle line, then again every 200 ms while the line downloads and while it uploads, and grades the increase on Waveform's bands, A+ to F.
One check
- Internet
One check after another, with your progress along the top and a plain verdict on each. Nothing you show the camera or say into the microphone leaves this page.
In short
Bufferbloat test: the answer first
A bufferbloat test measures how much your ping rises when the line is busy. This one takes the median round trip idle, then again every 200 ms while the line downloads and while it uploads, and grades the larger increase on Waveform's bands, A+ to F. It talks only to this site.
Reading your result
- Read the added milliseconds, not the idle ping
- A low idle ping that jumps under load is the problem bufferbloat names. The grade follows the increase, and the worse of the two directions sets it.
- Upload is where it usually shows
- The upstream is the narrow side of most home lines. A grade that is bad only on upload points at backups, sync and the router's upstream queue.
- Run it twice, cable and Wi-Fi
- If the cable grades well and Wi-Fi does not, the queue is in the wireless link, not the router's line.
What it measures
Measured here, not assumed.
- Idle latency
- Twenty small round trips to this site with nothing else running, the first two dropped as the connection opens. The median is the baseline.
- Latency while downloading
- A small round trip every 200 ms during five seconds of download over parallel streams, after the first second of ramp. The median is the loaded figure for that direction.
- Latency while uploading
- The same during the upload. Upload is where home routers queue most, because the upstream is the narrow side of most lines.
- The grade
- The larger of the two increases over idle, graded on Waveform's bufferbloat bands: A+ under 5 ms added, A under 30, B under 60, C under 200, D under 400, F beyond. The worse direction sets the grade; that is our choice, and the stricter reading.
- Speed and jitter alongside
- Download and upload speed and RFC 3550 jitter come from the same run, because a grade means more beside the speed it was measured at.
If it fails
The usual failures, and what fixes each.
- The grade is C or worse
- Turn on Smart Queue Management (SQM) on the router, often listed under QoS and using fq_codel or CAKE, and set its limits a little below the speeds this test measured. Many provider routers have no such setting; a router of your own in front of them can.
- It is bad only while uploading
- Pause cloud backups, photo sync and uploads on every device, then run again. If the grade recovers, set an upload limit in the backup app or the router.
- It is bad only on Wi-Fi
- Run once with a cable. If the cable grades well, the queue is in the wireless link: move closer, use the 5 GHz band, or keep the console or PC on a cable.
Where a browser stops
What it cannot tell you.
- Latency to a game server or a call service elsewhere. The round trips go to this site; another server's path can queue differently.
- Packet loss. A loss test needs a relay server at the other end, which we do not run, so it is reported as not measured.
- Wi-Fi signal, band and channel, which browsers cannot read.
- A queue that only fills under heavier traffic than five seconds each way. Run the test while the house is busy to see that.
Privacy
Nothing leaves this page.
The camera and microphone are read on this page and stopped as soon as they have been measured. The clip you can play back lives in the browser's memory and is discarded when you leave. The location check discards the position. The internet test sends random bytes to this site and nothing else. The result is stored nowhere unless you ask for it by email, and then only the fact that an email was sent is kept.
Questions
Bufferbloat test, answered
- What is bufferbloat?
- Latency that rises when the line is busy, because a router or modem holds too much data in its queue. A connection with a good idle ping can still lag in a game or freeze a call whenever someone else downloads or uploads.
- What bufferbloat grade is good for gaming?
- The fewer milliseconds the line adds under load, the less a busy house shows in a game. On Waveform's bands, A+ adds under 5 ms and A under 30 ms; from C upward, 60 ms or more is added while the line is busy.
- Why is my bufferbloat worse on upload?
- The upstream is usually the slower side of a home line, so it fills first, and many routers queue deeply on it. Uploads from backups, cameras and game updates fill it without anyone noticing.
- How do I fix bufferbloat?
- Smart Queue Management on the router is the fix that targets it: it keeps the queue short by limiting the line a little below its speed. A cable instead of Wi-Fi, and pausing big uploads, help too.
- Is bufferbloat the provider's fault or my router's?
- Usually the queue that fills is in the home router or modem, on the upload side. Smart Queue Management on a router you control keeps it short; the provider's line speed is rarely the cause on its own.
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