Overview: What Happens During a Speed Test?
When you click "Start Test" on Speed Test Plus, our tool performs a series of carefully orchestrated measurements to determine four key metrics about your internet connection: ping (latency), jitter, download speed, and upload speed.
Each measurement uses different techniques and runs in a specific order to ensure accuracy. The entire process typically takes 15-30 seconds depending on your connection speed.
Phase 1: Ping & Jitter Measurement
The test begins by measuring latency (commonly called "ping"). This is the time it takes for a tiny data packet to travel from your device to our test server and back.
How We Measure Ping
- We send 20 consecutive small HTTP requests to Cloudflare's edge servers
- Each request measures the round-trip time in milliseconds
- We use the median value (not average) to eliminate outliers
- The first and last readings are trimmed for accuracy
How We Calculate Jitter
Jitter represents the variation in ping times. We calculate it by measuring the average difference between consecutive ping readings. Low jitter means your connection is stable; high jitter indicates inconsistency that can affect real-time applications like gaming and video calls.
Pro Tip: A ping under 30ms and jitter under 5ms is considered excellent for gaming and video conferencing.
Phase 2: Download Speed Test
After measuring latency, the tool tests your download speed — how fast data can travel from the internet to your device.
Our Download Testing Methodology
- We start with small file downloads (256KB) and progressively increase size (up to 25MB)
- This adaptive approach ensures both slow and fast connections are tested accurately
- Each download uses streaming to measure speed in real-time as data arrives
- We track bytes received per second and convert to Megabits per second (Mbps)
- Multiple rounds at optimal file sizes improve statistical accuracy
- We take the top 60% of measurements to exclude slow-start effects
The total download test runs for up to 10 seconds, adapting the number of rounds based on your connection speed. Fast connections will test with larger files, while slower connections use smaller ones to provide quicker results.
Phase 3: Upload Speed Test
The upload test measures how fast data travels from your device to the internet.
Our Upload Testing Methodology
- We generate random data blocks of increasing size (256KB to 2MB)
- Each block is sent to the test server via HTTP POST
- We measure the total time from request start to server acknowledgment
- Multiple rounds improve accuracy, similar to the download test
- Upload tests run for up to 8 seconds total
Upload speeds are typically lower than download speeds because most ISP plans are asymmetric — designed to prioritize downloading over uploading.
Ensuring Accuracy
Speed Test Plus employs several techniques to maximize accuracy:
- Cloudflare Edge Network: We test against Cloudflare's servers, which are located in 300+ cities worldwide, minimizing geographic distance effects
- Statistical Analysis: We use median values and top-percentile filtering to remove outliers and slow-start artifacts
- Adaptive Sizing: File sizes automatically scale based on your connection speed
- Cache Prevention: Every request includes unique parameters to prevent browser caching
- Stream-Based Measurement: Download speeds are measured using the Streams API for real-time accuracy
Factors That Affect Your Results
Several factors can influence your speed test results:
| Factor | Impact | Solution |
|---|---|---|
| Wi-Fi vs Ethernet | Wi-Fi can reduce speeds by 20-50% | Use a wired Ethernet connection for true speeds |
| Network congestion | Peak hours slow everyone down | Test at different times of day |
| Other devices | Bandwidth shared across devices | Pause other devices during test |
| VPN/Proxy | Adds extra routing and encryption overhead | Disable VPN for accurate results |
| Browser extensions | Ad blockers can interfere | Disable extensions or use incognito mode |
| Router quality | Older routers bottleneck speed | Upgrade to Wi-Fi 6/6E router |
Understanding Speed Units
Internet speed is measured in Mbps (Megabits per second). Here's a quick reference:
- 1 Mbps = 1,000,000 bits per second
- 1 byte = 8 bits
- 1 MB/s (Megabytes per second) = 8 Mbps
- So a 100 Mbps connection can download about 12.5 MB per second
ISPs typically advertise in Mbps, while file managers show download progress in MB/s. Don't confuse the two — they differ by a factor of 8!
Best Practices for Accurate Testing
- Use Ethernet: Connect directly to your router for the most accurate results
- Close other apps: Stop all downloads, streams, and background processes
- Disconnect other devices: Or at least ensure they're not using heavy bandwidth
- Disable VPN: VPNs add latency and may reduce throughput
- Run multiple tests: Take 3+ tests and average the results
- Test at different times: Peak vs off-peak hours can show significant differences
- Restart your router: If speeds seem abnormally low, a restart often helps