Cable vs Fiber Real-World Speeds: What You Actually Get vs What They Advertise
Both cable and fiber deliver close to or above their advertised download speed, even at peak. The real gap is upload and latency, not the headline download number. Here is the full FCC data.
Data: FCC Measuring Broadband America (13th Fixed Report, published 2024; Sept-Oct 2022 panel data), Ookla Speedtest Index Q1 2026. Updated April 2026.
Speed Reality Calculator
Based on FCC Measuring Broadband America 2024 medians. Individual results vary by provider, location, and equipment.
The FCC Data
The FCC Measuring Broadband America program measures actual delivered speeds from ISP customers using Whiteboxes installed in homes, measuring real connections during real usage hours. The key finding from the 13th Fixed report (published 2024): of the 12 ISP/technology configurations tested, eight met or exceeded their advertised download speed during peak hours (7-11pm). The four that fell short, landing at 86 to 90 percent, were all DSL. The lowest performers were DSL providers at 63 to 72 percent.
So on headline download speed, cable and fiber are close: both deliver roughly what they advertise, with fiber typically a few points higher because providers over-provision. The genuine, durable difference is elsewhere: cable upload is capped at 20 to 50 Mbps versus fiber's symmetric 900-plus, and cable latency runs 15 to 35ms versus fiber's 5 to 15ms. That is where the comparison is actually decided, not in the download column.
Full Speed Data Table
| Tech | Plan | Peak DL | Off-peak DL | Upload | Latency |
|---|---|---|---|---|---|
| Fiber | 100 Mbps | 105 Mbps | 108 Mbps | 100 Mbps | 8 ms |
| Fiber | 500 Mbps | 520 Mbps | 535 Mbps | 500 Mbps | 8 ms |
| Fiber | 1 Gbps | 1040 Mbps | 1070 Mbps | 940 Mbps | 8 ms |
| Cable | 300 Mbps | 300 Mbps | 312 Mbps | 20 Mbps | 22 ms |
| Cable | 500 Mbps | 495 Mbps | 520 Mbps | 35 Mbps | 22 ms |
| Cable | 1 Gbps | 965 Mbps | 1035 Mbps | 50 Mbps | 25 ms |
| 5G Home | Typical | 150 Mbps | 220 Mbps | 25 Mbps | 55 ms |
Your Wifi Is Probably the Real Bottleneck
Before blaming your ISP, check your router. Most households cannot use their full plan speed over wifi due to router limitations:
| Wifi Standard | Practical ceiling | Common in |
|---|---|---|
| Wifi 5 (802.11ac) | 300-600 Mbps real-world | Routers 2015-2020 |
| Wifi 6 (802.11ax) | 600-1,200 Mbps real-world | Routers 2019-present |
| Wifi 6E (6 GHz band) | 1,200-2,400 Mbps real-world | Routers 2021-present |
| Wifi 7 (802.11be) | 2,400-5,000 Mbps real-world | High-end routers 2024+ |
To test your true connection speed: connect a laptop directly to your router via ethernet and run a speed test. This isolates ISP speed from wifi. If ethernet is fast but wifi is slow, your router is the bottleneck, not your ISP.
How to Test Your Speed Properly
- 01.Plug your device into the router via ethernet cable (not wifi)
- 02.Close all other tabs and applications that might use bandwidth
- 03.Run the test at least 3 times and note the median
- 04.Test at off-peak (10am weekday) and peak (8pm weekday) for comparison
- 05.Use fast.com (Netflix CDN), speedtest.net (Ookla), and waveform.com for multi-source comparison