Fibre vs cable vs DSL: what's actually delivering your broadband?
Three very different technologies are sold under the same word: “broadband.” Which one is feeding your house decides what speeds you can realistically expect, how even your upload is, and how stable the line gets in bad weather or peak hours. Here's the honest comparison.
- Full fibre (FTTP / FTTH) is the best: symmetric speeds up to 8 Gbps, low latency, low jitter, very stable.
- Cable is fast on download (typically 300–1200 Mbps) but uploads are far slower and a single neighbourhood shares one segment.
- DSL uses telephone wire. Real-world speeds usually 10–80 Mbps. Fine for one or two people; struggles for modern households.
- If you have “fibre” on your bill, check — the marketing word covers both true full fibre and copper-to-the-home with fibre only to the cabinet (FTTC).
The three technologies, very briefly
All three deliver the same internet, but the last stretch into your house is wildly different physics.
Full fibre (FTTP / FTTH)
Strands of glass run from a local exchange all the way to a small box on the outside of your house. Data travels as pulses of light. Fibre has no electrical interference, doesn't degrade with distance the way copper does, and can carry obscene amounts of bandwidth. In the UK this is sold as “Full Fibre” or “FTTP”; in the US it's most commonly Verizon Fios, AT&T Fiber, Frontier Fiber, Google Fiber and similar.
Cable (DOCSIS)
The coaxial cable originally laid for cable television. The signal is digital these days (DOCSIS 3.1 is the dominant standard; DOCSIS 4.0 is rolling out). Cable is fast for download, slower for upload, and your local segment is shared with the neighbourhood — so evening congestion is real. Comcast Xfinity, Spectrum, Virgin Media, and Cox are the big names.
DSL / ADSL / VDSL
The same copper telephone wire that once carried your landline, repurposed for data. DSL degrades sharply with distance from the local exchange or street cabinet, so two houses on the same street can get very different speeds. The newest variant (G.fast / vectored VDSL) can push 300 Mbps over very short copper runs, but most households see 20–80.
Real-world speeds (not marketing speeds)
Marketing tends to quote the top of the range. Here's what each technology typically delivers on a healthy line — not the worst case, not the brochure case.
| Technology | Typical download | Typical upload | Ping | Stability |
|---|---|---|---|---|
| Full fibre (FTTP) | 300 Mbps – 8 Gbps | Symmetric (same as download on most plans) | 3–10 ms | Excellent |
| Cable (DOCSIS 3.1) | 300 Mbps – 1.2 Gbps | 20–50 Mbps (asymmetric) | 8–25 ms | Good off-peak, drops in evening |
| VDSL / G.fast | 40–300 Mbps | 5–50 Mbps | 10–30 ms | OK; sensitive to distance & weather |
| ADSL2+ | 5–20 Mbps | 0.5–1 Mbps | 20–50 ms | OK; fades with line length |
| 5G fixed wireless | 100–800 Mbps | 10–80 Mbps | 15–40 ms | Variable with mast load |
How to tell what you actually have
ISP marketing happily uses “fibre” to mean anything where there's a strand of glass somewhere in the path, even if your house is still connected over copper. Three quick checks:
- Look at the cable coming into your house. If it's a phone-style RJ11 going into a master socket, that's DSL/VDSL. A coax screw-on connector to the wall is cable. A small white or grey termination box (an “ONT”) with a tiny fibre cable into it is true full fibre.
- Check the upload speed. Run a speed test. Anything above 80 Mbps upload on a residential plan almost certainly means full fibre. Symmetric speeds (download equals upload) are full fibre's tell.
- Check the wording on your contract. “FTTP” or “Full Fibre” means glass to the house. “FTTC” or “Fibre to the Cabinet” means copper into the house. “Gigabit” usually means cable or full fibre but isn't a guarantee.
Run a speed test now
The upload number especially will tell you a lot. Symmetric = full fibre.
Side-by-side: who wins for what
Full fibre wins for
- Households uploading large files (creators, photographers, backups).
- Multiple simultaneous 4K streams.
- Video calls and remote work (low jitter, fast upload).
- Future-proofing — the same fibre easily supports 10 Gbps when ISPs roll it out.
- Anyone who hates buffering.
Cable is fine for
- Heavy download users who barely upload.
- Households where fibre isn't yet available on the street.
- Areas with low evening congestion (apartment blocks vary wildly).
DSL is fine for
- Singles or couples with light usage.
- Backup line for outages.
- Rural areas where it's all you can get.
5G fixed wireless is fine for
- Renters who can't pull new cable.
- Temporary setups.
- Areas with strong, lightly-loaded 5G coverage.
What about the UK vs the US specifically?
The big-picture story is similar — full fibre is the best, cable is fast for download and weak for upload — but the rollout state differs.
UK: the Ofcom Connected Nations data shows roughly two-thirds of UK premises now reach full fibre at least one network, with Openreach, CityFibre and a wave of altnets driving build. Virgin Media's network is mostly DOCSIS cable, with patches of XGS-PON fibre rolling out. Most “fibre” plans sold under 100 Mbps are actually FTTC over copper.
US: FCC data shows full fibre coverage growing fastest in urban areas (Verizon Fios, AT&T Fiber, Frontier, Google Fiber) while wide swathes of the country are still served primarily by cable (Comcast, Spectrum, Cox). DSL is increasingly being phased out as the legacy carriers retire copper.
The simple recommendation
If full fibre is available at your address, take it — even if a cable plan looks cheaper or faster on download. The upload, latency and stability difference is the kind of thing you stop noticing after a week because it just works.
If you're stuck on cable or DSL, focus less on the headline Mbps number and more on the upload and ping figures. Those are what make a connection feel responsive day to day.