Key points
- A speed test measures download, upload, ping and jitter.
- Speed is reported in megabits per second (Mbps) - Bigger is faster.
- For accuracy, use a wired connection and pause other downloads.
- Run the test a few times and compare against the plan you pay for.
What an internet speed test actually is
An internet speed test is a quick benchmark that measures the real performance of your connection at this moment. Your provider sells you a plan - Say "300 Mbps" - But that headline number is a maximum under ideal conditions. A speed test tells you what you're actually getting, right now, on the device you're using.
The test works by moving real data between your browser and a nearby test server and timing how long it takes. Because it measures the whole path - Your device, your Wi-Fi, your router, your provider's network and the wider internet - It reflects your true day-to-day experience rather than a theoretical figure.
The four core metrics
Every reputable speed test reports the same four values. Here is what each one means and why it matters.
Download speed
Download is how quickly data travels to you. It governs streaming video, loading web pages, downloading files and receiving updates. It's the number most people mean when they talk about "internet speed," and it's usually the largest. Read the full download-speed guide →
Upload speed
Upload is how quickly data travels from you to the internet - Sending email attachments, backing up photos, joining a video call or posting a clip. On cable and DSL connections it's much slower than download. Read the full upload-speed guide →
Ping (latency)
Ping, measured in milliseconds, is the round-trip delay for a small packet to reach the server and come back. Low ping means a responsive connection - Essential for gaming and video calls. A great connection can have high download speed but still feel sluggish if ping is high. Read the full ping guide →
Jitter and packet loss
Jitter is how much your ping varies from one moment to the next, and packet loss is the share of data that never arrives. Both measure stability. High jitter or any packet loss is what makes calls stutter and games rubber-band, even when your speed looks fine. Read the full jitter guide →
How the test works, step by step
- Ping phase. The test sends a series of tiny requests to the server and times each round trip to calculate ping, jitter and any packet loss.
- Download phase. Your browser pulls a stream of data from the server for several seconds, continuously calculating throughput in megabits per second and settling on a stable figure.
- Upload phase. The process reverses: your browser sends data to the server and measures how fast it leaves your connection.
Modern tests - Including this one - Open several connections at once ("multi") to fully saturate a fast line, or a single connection to mimic one real transfer. You can switch between the two modes on our home page.
Speed is measured in megabits per second (Mbps), but file sizes are in megabytes (MB). There are 8 bits in a byte, so a 100 Mbps connection downloads about 12.5 MB every second - Divide Mbps by 8 to estimate real download rates.
How to get an accurate result
- Use a wired connection where possible - Wi-Fi adds variability and can cap your speed below your plan.
- Pause other activity - Streaming, cloud backups and big downloads on other devices all compete for bandwidth.
- Close background apps and pause VPNs, which route traffic through distant servers and lower results.
- Test more than once and at different times of day; evenings are typically the most congested.
- Test near your router first to separate a Wi-Fi problem from a connection problem.
Reading your numbers
Compare your download result to the plan you pay for. Landing within about 10–20% of the advertised figure over a wired connection is normal. If you're consistently far below it, the cause is usually Wi-Fi, an aging router, or congestion - See our guide to fixing slow internet. If wired results are still far off, it's worth contacting your provider.
Not sure how much speed you actually need? Our speed requirements guide breaks it down by activity, from casual browsing to a 4K household.