Terms used on this site
Mbps, jitter, TURN. There's a bit of jargon around internet checks. Here's what the words mean, roughly in the order you'll meet them on the site.
Capacity
How much data your connection can move each second, usually in megabits per second (Mbps). We estimate download and upload separately. Even with plenty of capacity, calls and games can struggle if responses are slow or uneven.
Responsiveness
How quickly a small message gets an answer. We measure it as response time in milliseconds (ms). Lower means less waiting. Once there's enough capacity, games and calls rely on quick responses to keep things moving.
Response time
How long a small probe takes to reach the test destination and come back. We report the median, or middle reading, so one unusually slow reply cannot dominate the result.
Consistency (jitter)
How much response times jump around. Lower jitter means steadier replies. Uneven timing can accompany choppy audio or characters snapping back in a game, though our check measures the path to Cloudflare rather than your app's route.
Idle response
Response time before the check starts its download or upload transfers. We use it as the starting point for the busy comparison. Other people or apps may still be using your connection.
Busy response (added delay)
Response time while the check downloads or uploads. We grade the added delay by subtracting the idle median from the busy median, showing zero when there's no increase. A big jump can fit with traffic waiting in a queue, sometimes called bufferbloat. These readings cannot locate that queue or prove why a call froze.
Busy jitter
How much response times vary during a transfer. You'll see the reading without a grade. A short check cannot separate your connection's behavior from the effects of the traffic it creates.
Packet delivery (packet loss)
Whether small probes sent through a relay arrive. Full check sends 500 probes, so one missing probe is 0.2% loss. If none go missing, that describes this short window only. A failed relay connection leaves the reading unavailable.
Relay (TURN)
A server that forwards the packet-delivery probes using the WebRTC mechanism calls can use when a direct path is not available. If the relay connection fails, packet delivery is reported as unavailable rather than guessed.
Check profile
The set of measurements you choose. Full check includes download, upload, busy response, and packet delivery, using about 192 MB including estimated overhead. Lower data uses about 4 MB and skips upload and packet delivery. Actual usage can vary. Both profiles give estimates rather than measuring your line's maximum speed.
Test destination
Where the test traffic goes: Cloudflare's network. The check measures your path to Cloudflare, not to a particular game server, meeting service, or website.
Mbps versus MB/s
Bits and bytes. Eight bits make a byte, so 200 Mbps works out to about 25 MB/s before overhead. Speed tests quote Mbps. Download windows often show MB/s. Check those letters before comparing the numbers.
Baseline
A saved result taken before you change anything. Change one condition, repeat the same profile on the same device, then compare the two links.
Result link
A shareable URL holding a check's readings. Anyone with the link can see those readings. Links exclude network context and individual samples. Comparisons stay in page memory and disappear on reload.
Ethernet
A wired connection from the PC to the router. Comparing Wi-Fi against Ethernet helps investigate whether the wireless connection contributes to a symptom. A difference does not prove which device or network component is faulty.
ISP
Your internet service provider, the company you pay for the connection. Our check gives you readings to discuss with support. It cannot prove the provider caused a problem.
Want to see these in use? Start with a guide or check your connection.