Bufferbloat Test

How to use

1. Press Start test. Keep this tab in front while it runs. The whole test happens in your browser against Cloudflare's network, with no app and no account.
2. Let it load the line. It times your ping while the connection sits idle, then saturates your download and upload and times the ping again under that load. The gap between the two is your bufferbloat.
3. Read your grade. You get a letter from A+ to F, with your idle ping next to your loaded ping. The smaller the climb between them, the better your line handles a full load.

Why test this

Your game ran clean until your roommate's phone kicked off a cloud photo backup, and now every peek rubber-bands. Or the video call freezes the second you send a large attachment. That's bufferbloat. Your router hoards a backlog of packets when the line fills up, and your latency-sensitive traffic waits behind the bulk transfer. A plain speed test misses it because it reports your peak throughput, not what your ping does while that throughput is running. This is why a gigabit plan can still feel broken during a busy evening. The test loads your line on purpose and watches how far your ping climbs, so you find out whether a full download or a big upload is about to tank your match before it happens mid-game. One run tells you whether your connection holds steady when the household piles on traffic, or buckles under it.

What the results mean

The letter grade is the headline, from A+ down to F, and it scores one thing: how far your ping rises the moment your connection gets busy. A+ means your latency barely moves under a full load, so nothing else downloading in the house can touch your game or call. A D or F means your ping balloons under load. That's the freeze you hit mid-match when someone in the house starts a Netflix binge on the same Wi-Fi. Under the grade you see idle ping beside loaded ping, so you know exactly where your numbers land. A reading of 25 ms at rest and 220 ms once the pipe is full is nearly a 9x jump, and that ratio is the whole story behind the letter. Remember this is a queue problem, not a speed problem, so the answer is a router that keeps its queue short, not a faster plan. You also get your jitter and raw download and upload numbers, all from one pass. Test once on Wi-Fi and again wired to see which setup your buffer struggles with.

FAQ

What is a good bufferbloat grade?

A+ and A mean your ping barely moves under load, which is what you want for gaming and calls. B and C are usable but you may feel the occasional stall. D and F mean your latency more than doubles when the line gets busy, and that's when real-time apps fall apart. Aim for A, and treat anything under C as worth fixing.

What causes bufferbloat?

Your modem and router ship with buffers that are too big. When you saturate the connection, those buffers fill with a backlog of data, and your latency-sensitive packets wait in line behind the bulk transfer. A big upload, a cloud backup, or a game download running in the background is usually what tips a fine connection into a bad grade.

How do I fix bufferbloat?

Look in your router's settings for Smart Queue Management or QoS, usually under Advanced or Traffic Control. Turn it on and cap your upload and download rates at about 90 percent of your measured speed, since SQM can't do its job without knowing your real ceiling. A wired connection helps, and an older router with no queue control is worth replacing.

Does a faster internet plan fix bufferbloat?

No. Bufferbloat is a queue problem, not a bandwidth problem, so a gigabit line can still earn an F. Paying for more speed gives the buffers more data to hoard, not less. The fix is controlling how your router handles its queue, not adding megabits.

What is the difference between bufferbloat and jitter?

Jitter is how much your ping varies moment to moment, even on an idle line. Bufferbloat is the specific jump in latency that shows up only when the connection is loaded. A line can have low jitter at rest and still bloat badly under a download. Run the jitter test for the first and this one for the second.