Broadband is sold on download speed, but an increasing share of what you do online — video calls, cloud backups, sending files, live streaming — depends on the other direction. Upload is the figure buried in the small print, and on many plans it's a tiny fraction of the headline number. A “500 Mbps” cable plan with 20 Mbps upload is a sports car with a bicycle for a return journey.
Why upload is so much smaller on cable
It's not malice so much as legacy engineering. Cable broadband runs over coaxial networks originally built to push TV one way — into homes. DOCSIS, the cable data standard, historically allocates most of the usable spectrum to downstream and a thin slice to upstream, which is why cable plans are so asymmetric. Full fibre has no such constraint: light travels both ways equally well, which is why fibre providers increasingly sell symmetric plans — the same speed up and down. If you regularly send as much as you receive, that symmetry is the single best reason to switch to fibre where it's available; our ISP guides cover what to look for.
What upload-hungry activities actually need
- Video calls: roughly 2–4 Mbps upload per HD call. Modest — until two parents and a teenager are all on calls at once over a 10 Mbps upstream.
- Cloud backup & sync (OneDrive, iCloud, Google Photos, Dropbox): will happily saturate whatever upload you have. On a thin upstream, a phone backing up holiday videos can cripple every call in the house.
- Live streaming: Twitch and YouTube both recommend single-digit Mbps for a solid 1080p stream — commonly in the ~5–9 Mbps range depending on settings. The catch is that streaming needs that rate sustained and stable, with headroom for everything else. Streaming at 6 Mbps on an 8 Mbps upstream is asking for dropped frames.
- Sending large files: a 5 GB video file takes roughly an hour at 10 Mbps up, and a few minutes at 100 Mbps up. For anyone who works with media, upload is the job.
- Security cameras: each cloud-recording camera adds a constant 1–4 Mbps of upstream, around the clock.
The hidden failure mode: saturated upload breaks everything
Here's the part most people miss. When your upload pipe is completely full, even downloads and calls suffer, because the small acknowledgement packets your connection needs to send back get stuck in the queue. The symptom is a house where everything goes treacly whenever one device is uploading — classic bufferbloat. It's also why gaming ping spikes when someone starts a backup; competitive players should read our gaming connection guide alongside this one.
How to diagnose slow uploads
- Measure it. Run a free NetStartr test — the upload figure sits right next to download. Test wired if possible to take Wi-Fi out of the equation.
- Compare against your plan's advertised upload, not its download. Many people discover at this step that 20 Mbps up is all they ever paid for.
- If wired upload matches the plan but calls still break up, look at contention inside the house: pause cloud sync clients and camera uploads, then re-test. A router with smart queue management (SQM / QoS) can stop one uploader starving everyone else.
- If wired upload is far below plan, test at different times of day. Cable upstream is shared and congests at peak; consistently poor upload at 7 AM is grounds for a support ticket. Timestamped tests are your evidence.
- If Wi-Fi upload is much worse than wired, it's a signal problem — weak links degrade upload first because your device transmits with far less power than the router.
Rules of thumb when choosing a plan
- Casual household: 10–20 Mbps upload is liveable.
- Remote workers on daily calls: aim for 20–50 Mbps up.
- Streamers, creators, big-file workers, camera-heavy smart homes: 100 Mbps+ up, ideally symmetric fibre.
Next time an ISP flashes a big download number at you, ask the question they're not volunteering: and what's the upload?