Bufferbloat test
See how much your ping jumps when your connection is busy. A+ to F in about 20 seconds.
Press Go to start.
Results
- Download
- – Mbps
- Upload
- – Mbps
- Ping
- – ms
- Jitter
- – ms
- Packet loss (estimated)
- – %
- Bufferbloat
- –
Tests run against Cloudflare's speed servers.
What bufferbloat is
Bufferbloat is the extra delay your connection adds when it is busy. Speedhound measures your ping while it downloads and uploads, then grades the added delay from A+ (under 5 ms) to F (400 ms or more).
Routers and modems keep a queue of packets waiting to be sent. When that queue is too long, a big upload or download fills it, and everything else, including a video call or a game packet, waits in line behind it. Your speed stays high while the connection feels slow. A plain speed test does not show it because it only measures how much data moves, not how long each packet waits.
What your bufferbloat grade means
| Grade | Added latency under load | What it feels like |
|---|---|---|
| A+ | Under 5 ms | Calls and games are unaffected by other traffic. |
| A | 5–30 ms | Fine for everything, including competitive games. |
| B | 30–60 ms | Rarely noticeable. Fine for most households. |
| C | 60–200 ms | Calls and games stutter when someone else uploads or streams. |
| D | 200–400 ms | Calls break up and games lag during downloads. |
| F | 400 ms or more | The connection feels frozen while it is busy. |
Added latency is your median ping during the busier of the download and upload phases, minus your idle ping. How the grade is calculated.
How to fix bufferbloat
- Test over a cable. Plug in with Ethernet and pause other downloads, so you are measuring the router and not Wi-Fi interference.
- Turn on smart queue management. Look in your router's settings for SQM, Smart Queue, QoS, fq_codel or CAKE. These keep the queue short so small packets are not stuck behind large transfers.
- Set the limits just below your real speeds. Enter about 90% of the download and upload speeds from the test above. That moves the queue into your router, where it is managed, instead of your modem or your provider's equipment.
- Retest. Run the test again after each change. Many routers ship with queue management off; a router that supports it can turn a D into an A.
- If your router has no such option, replace it with one that supports SQM or CAKE. Provider-supplied modem-routers often cannot be changed, so a separate router behind it is the usual fix.
Low ping alone is not enough. See what a good ping is and how much speed you need.
Questions
What is bufferbloat?
Bufferbloat is the extra delay that builds up when your router or modem holds too much data in a queue while your connection is busy. Pages, calls and games wait behind that queue, so lag spikes even though your Mbps number looks fine.
What is a good bufferbloat grade?
A or A+ is good: your ping rises by less than 30 ms under load. B is fine for most people. C and below means calls and games will stutter whenever someone else is uploading or streaming.
Does bufferbloat affect gaming?
Yes. Games send small packets all the time and need them to arrive on schedule. When a download or upload fills the queue, those packets wait, and you see ping spikes, rubber-banding and delayed inputs.
Does bufferbloat affect Ethernet?
Yes. The queue is in your router or modem, not in the Wi-Fi link, so a cable does not remove it. Ethernet does remove Wi-Fi noise, which makes the test result easier to read.
Is bufferbloat real or just a gamer myth?
It is real and measurable: you can see it as the gap between your idle ping and your ping during a download or upload. This test shows that gap in milliseconds.
How long does the bufferbloat test take?
About 20 seconds. It measures idle ping, then measures ping again while downloading and while uploading, and grades the largest increase.
More from Speedhound
- Speed testDownload, upload, ping, jitter and bufferbloat in 20 seconds.
- Download time calculatorHow long a file takes at your speed.
- Good internet speedHow many Mbps you need for your household.
- Good pingWhat ping, jitter and packet loss numbers mean.