Measure download speed, upload speed, idle latency, jitter, and latency under load with Cloudflare's official browser speed-test engine. For a deeper diagnosis, also try the Bufferbloat Test.
Speed Test
LiveAbout this calculator
This browser-based tool uses the official Cloudflare SpeedTest engine. It runs progressively larger download and upload requests against Cloudflare's edge network, filters unusably short samples, and summarizes the valid measurements. Download speed describes data arriving at your device; upload speed describes data sent from it.
The test also measures idle latency and jitter, then sends small latency probes while the download and upload phases are active. This makes it possible to distinguish a fast connection from one whose responsiveness degrades when busy. For a focused explanation and grading of that behavior, use the Bufferbloat Test.
Why results differ between speed tests
Server location, routing, protocol, connection count, test duration, Wi-Fi conditions, device performance, and other traffic all affect a result. Therefore, a Numeros result does not have to match Speedtest.net, Fast.com, or an ISP-hosted test. Compare repeated tests made with the same tool, device, and connection conditions when tracking performance over time.
| Activity | Recommended download | Recommended upload |
|---|---|---|
| Basic browsing, email | 5–10 Mbps | 1–3 Mbps |
| HD video streaming (per stream) | 5–25 Mbps | — |
| 4K streaming (per stream) | 25+ Mbps | — |
| Video calls (per person) | 3–5 Mbps | 3–5 Mbps |
| Cloud backup, large uploads | — | 20–50 Mbps |
| Busy household, multiple 4K streams | 100+ Mbps | 10–20 Mbps |
How to interpret the activity guidance
The streaming, gaming, and video-call labels are practical estimates based on bandwidth, idle latency, jitter, and loaded latency when available. They are not service guarantees. For a more detailed gaming check, use the Gaming Network Quality Calculator.
What to expect from your result
A single run is a snapshot, not a permanent rating of your connection. For a useful comparison, run three tests at different times, keep the device and connection method the same, and compare the median result with the typical speed stated for your plan. If repeated wired tests remain much lower than expected, save the results and contact your Internet provider.
Frequently asked questions
Why is my upload speed so much lower than download?
Most residential plans are asymmetric by design — cable and DSL in particular allocate far more capacity to download than upload, since most household traffic (streaming, browsing) is download-heavy. Fiber plans are more often symmetric.
My result is much lower than my plan speed. What's wrong?
Check Wi-Fi vs Ethernet first, then confirm nothing else on the network is active during the test. If a wired, otherwise-idle test still comes in well under 80% of your advertised speed across several runs, that's worth documenting for your ISP.
Why do different speed test tools give different numbers?
Different test servers, connection counts, test durations, and network paths all produce genuinely different (and each individually valid) measurements of a connection that itself fluctuates. Pick one tool and track your own trend on it rather than treating any single number as absolute truth.
Is this test accurate on a gigabit or multi-gigabit connection?
Browser-based tests can be limited by your device's own network stack well above 1 Gbps. For lines faster than roughly 2–5 Gbps, a dedicated speed-test application often measures more accurately than any browser-based tool, this one included.
What happens to my test result?
Numeros does not create a personal speed-test history. The official engine sends completed measurement results to Cloudflare for aggregated Internet-quality insights. Review Cloudflare's privacy information if you need more detail before running the test.
Should I use this or the Bufferbloat Test?
Use this one for "how fast is my connection" — a quick download/upload/ping number. Use the Bufferbloat Test when the number here looks fine but calls and games still feel laggy while the connection is busy; it measures how much your latency degrades specifically under load, which this tool doesn't dig into.
Why does the speed change during the test?
The engine starts with smaller transfers and progresses to larger ones so it can reach a useful measurement duration without immediately wasting large amounts of data. Available capacity can also change from moment to moment. Record the completed result rather than an early live update.
Sources
- FCC Measuring Broadband America — guidance and reports about fixed broadband performance.
- Cloudflare SpeedTest — official engine, configuration, measurement methodology, and result API.
- Cloudflare Speed Test — Cloudflare's reference implementation of the same measurement engine.
Related networking calculators
See the full list of Networking tools, or continue with:
- Bufferbloat Test — measure how latency changes while the connection is busy
- Ping Calculator — interpret round-trip delay for gaming, calls, and browsing
- Jitter Calculator — analyze variation between consecutive latency readings
- Packet Loss Calculator — calculate lost packets and connection reliability
- Download Time Calculator — estimate file-transfer time from the measured speed
- Gaming Network Quality Calculator — combine ping, jitter, packet loss, and speed into a gaming assessment