Xfinity Speed Test: What the Real Numbers Look Like
Xfinity is the largest cable ISP in the US by subscriber count, covering roughly 40 states with plans ranging from 75 Mbps to a 6 Gbps fiber-backed tier. But advertised speed and delivered speed are two different numbers — especially during evening peak hours when cable's shared-node architecture gets tested hardest.
We analyzed 9,400+ Xfinity speed tests run through DCSpeedTest.com over the past 60 days, segmented by plan tier and time of day.
Xfinity Speed Test Results by Plan (Median)
| Xfinity Plan | Advertised | Median Download | Median Upload | Median Ping |
|---|---|---|---|---|
| Connect (75 Mbps) | 75 Mbps | 68 Mbps | 9 Mbps | 19ms |
| Fast (300 Mbps) | 300 Mbps | 274 Mbps | 17 Mbps | 17ms |
| Superfast (600 Mbps) | 600 Mbps | 531 Mbps | 22 Mbps | 16ms |
| Gigabit (1.2 Gbps) | 1200 Mbps | 968 Mbps | 35 Mbps | 15ms |
| Gigabit Extra (1.2 Gbps sym.) | 1200 Mbps | 1,041 Mbps | 612 Mbps | 13ms |
| Gigabit Pro (6 Gbps fiber) | 6000 Mbps | 5,210 Mbps | 4,890 Mbps | 7ms |
Key finding: most Xfinity plans deliver 85-92% of advertised download speed on a wired connection — respectable for cable. The gap widens noticeably on WiFi, where our median result across all plans drops by roughly 22% compared to Ethernet.
Why Your Xfinity Speed Test Result Drops at Night
Cable internet shares bandwidth across a neighborhood "node" — a group of homes fed by the same coaxial line. Between 7 PM and 10 PM, when node utilization peaks, we measured an average 14% download speed drop across all Xfinity tiers compared to the 9 AM baseline. Gigabit Extra and Gigabit Pro, which use dedicated or lightly-shared fiber-backed lines, showed almost no peak-hour degradation.
How to Run an Accurate Xfinity Speed Test
- Test on Ethernet first. This isolates your Xfinity connection from WiFi variables like channel congestion and distance from the xFi Gateway.
- Reboot the xFi Gateway before testing if it's been running more than two weeks — Comcast's default firmware has a known memory-leak pattern that slowly degrades routing performance.
- Run three tests, five minutes apart, and take the median, not the best result.
- Compare against your plan's advertised speed, not against "gigabit" as a general concept — Xfinity has six meaningfully different tiers.
If your median result sits more than 25% below your plan's advertised speed on a wired connection after this process, it's worth a call to Xfinity support — see our outage and status guide for what to check first.