Internet Speed Tests: Measuring Bandwidth and Latency

Your Internet feels slow. Is it actually slow, or does it just feel that way? Speed tests answer this question by measuring what your connection can actually do—download speed, upload speed, and latency. But understanding what these numbers mean, and what they don't mean, is the difference between useful diagnosis and false confidence.

What Speed Tests Actually Measure

A speed test transfers data between your device and a test server, measuring three things:

Download speed — how fast data arrives at your device, measured in Mbps (megabits per second). This determines how quickly web pages load, videos stream, and files download.

Upload speed — how fast your device sends data, also in Mbps. This matters for video calls, cloud backups, and sharing files.

Latency — how long a signal takes to make a round trip, measured in milliseconds (ms). This determines how responsive your connection feels.

Modern speed tests open multiple simultaneous connections to saturate your available bandwidth, giving you the best-case measurement of what your connection can do.

The Catch: Best-Case Scenarios

Your speed test shows what your connection can do when trying its hardest. Real life is rarely trying that hard.

A 100 Mbps speed test result doesn't mean you'll download files at 100 Mbps from anywhere on the Internet. It means you achieved 100 Mbps to that specific test server under ideal conditions. The server you're actually downloading from might be slower. Your WiFi might be congested. Someone else in your house might be streaming.

Speed tests are like testing your car's top speed on an empty highway. Useful to know, but not representative of your daily commute.

Popular Speed Test Services

Speedtest by Ookla (speedtest.net) — The most recognized test, with servers everywhere. Shows download, upload, latency, and jitter.

Fast.com — Netflix's test, focused on download speed. Tests against Netflix's servers, so it shows what you'd actually get streaming Netflix.

Google's built-in test — Search "speed test" on Google. Quick and convenient.

Cloudflare Speed Test (speed.cloudflare.com) — Tests against Cloudflare's global network. Useful for seeing latency to multiple locations.

Different tests use different servers, so results vary. This isn't a bug—it reveals that your performance depends on where you're connecting to.

Reading Download Speed

1-5 Mbps — Basic web browsing works. HD video struggles. Multiple devices will fight for bandwidth.

5-25 Mbps — Handles HD streaming on one or two devices. Adequate for typical use.

25-100 Mbps — Multiple HD streams, video calls, fast downloads. Comfortable for most households.

100-500 Mbps — 4K streaming, large file transfers, many simultaneous users. More than most people need.

500+ Mbps — Often exceeds what applications can actually use. Useful for large households or businesses.

Compare your results to what your ISP advertises. They promise "up to" a certain speed—the same way a car advertises "up to" 150 mph. You're not getting that in rush hour, and you're not getting advertised speeds during peak Internet hours.

Reading Upload Speed

Upload speed matters when you're sending data: video calls, cloud backups, uploading files, streaming yourself.

Most residential connections are asymmetric—download far exceeds upload. ISPs assume you consume more than you create.

1-5 Mbps upload — Email and basic video calls work. Large uploads take forever.

5-20 Mbps upload — HD video conferencing works well. Reasonable for cloud backups.

20+ Mbps upload — Content creators, heavy uploaders, and businesses need this range.

If video calls constantly freeze on your end while everyone else looks fine, check your upload speed.

Reading Latency

Latency measures responsiveness—how quickly your connection reacts. Bandwidth is how much water your pipe carries; latency is how long it takes for the water to arrive after you turn the faucet.

0-20ms — Excellent. Gaming, video calls, and everything else works perfectly.

20-50ms — Good. Most applications work well.

50-100ms — Acceptable. Real-time applications might feel slightly sluggish.

100-300ms — Noticeable delays. Video calls lag. Gaming becomes frustrating.

300+ ms — Real-time applications become nearly unusable.

Satellite Internet inherently has 500-800ms latency because signals must travel to space and back. No amount of bandwidth fixes this.

Jitter: The Hidden Problem

Jitter measures how much your latency varies. Consistent latency (low jitter) matters more than low latency for real-time applications.

Imagine a video call where packets arrive at 30ms, then 80ms, then 20ms, then 100ms. The average is fine, but the variation causes choppy audio and frozen video.

Under 10ms jitter — Stable connection. Real-time applications work smoothly.

Over 30ms jitter — Unstable connection. Video calls suffer even if average latency looks acceptable.

Why Results Vary

Server distance — Tests to nearby servers show better results than distant ones. This is physics, not a problem.

Time of day — Everyone streams Netflix at 8 PM. Your ISP's network gets congested. Test at different times to see the pattern.

WiFi vs. Ethernet — WiFi adds overhead, interference, and variability. Test via Ethernet cable to see your connection's true capability.

Your device — Old hardware or a device running background updates can't achieve full speeds. The bottleneck might be your laptop, not your ISP.

VPNs — Testing through a VPN measures VPN performance, not your raw connection.

Running Reliable Tests

For accurate results:

1. Connect via Ethernet if possible
2. Close other applications and browser tabs
3. Make sure no one else is using the connection heavily
4. Test at different times of day
5. Run multiple tests and look for patterns

Single tests are snapshots. Patterns tell the real story.

Diagnosing Common Problems

Results far below what you're paying for: Test via Ethernet at different times. If consistently low, document results and contact your ISP. "I'm paying for 100 Mbps and getting 25 Mbps at 2 PM on a Tuesday via Ethernet" is a conversation starter.

Good speed test but slow in practice: Speed tests measure bandwidth to optimized servers. If Netflix buffers despite a good speed test, the problem is between Netflix and you—possibly ISP throttling, possibly Netflix's servers, possibly your WiFi.

WiFi slower than Ethernet: This is normal. If the gap is huge, investigate WiFi interference, router placement, or whether you need a better router.

Slow only at certain times: Network congestion. Your ISP's infrastructure might be oversubscribed in your area. This is common and frustrating—you're sharing bandwidth with your neighbors.

High latency despite good bandwidth: Distance to servers, inefficient routing, or satellite/cellular connections. Bandwidth and latency are independent—you can have plenty of one and not enough of the other.

Packet Loss

Some tests measure packet loss—what percentage of data fails to arrive.

0-1% — Normal. Every network drops occasional packets.

1-2.5% — Noticeable in video calls and gaming. Worth investigating.

2.5%+ — Significant problems. Something is wrong—congestion, bad cables, failing equipment, or ISP issues.

Mobile Testing

Mobile speeds vary wildly based on signal strength, network congestion, technology (4G vs 5G), and whether you're moving or stationary.

Test where you actually use your phone. A speed test next to a cell tower means nothing if you work in a basement.

What Speed Tests Can't Tell You

Speed tests don't reveal:

• Whether your ISP throttles specific services (like Netflix or BitTorrent)
• Why a specific website is slow (could be their servers, not your connection)
• WiFi dead spots in your house
• Whether your router is the bottleneck

Speed tests are one diagnostic tool among many. They answer "what can my connection do?" not "why is this specific thing slow?"