Why is my upload speed so much slower than my download?
On most UK connections the asymmetry is designed in, not a fault. What sets your upload figure, when it genuinely matters, and the one symptom that means something is actually wrong.
- Difficulty
- beginner
- Time
- 10 min
- Read
- 3 min
Short answer
Most UK broadband is deliberately asymmetric: the line is configured to give far more download than upload because that is what most households use. On part-fibre connections the upload is typically a small fraction of the download. Full fibre packages vary from similarly asymmetric to fully symmetric. It is only a fault if your upload has dropped from what it used to be.
Nobody notices upload speed until they start working from home, sending large files, or running cameras. Then it becomes the number that governs everything, because a video call, a cloud backup and a doorbell all push data outward. The frustration is that the headline figure on every broadband advert is the download, and the upload is often only in the small print.
Step by step
- Find out what technology your line actually uses.Part fibre — fibre to a street cabinet and copper for the last stretch — is inherently asymmetric because of how the copper section is configured. Cable is asymmetric by design. Full fibre to the property can be either, and the package decides.
- Look up the upload figure in your contract, not the advert.Providers must publish an upload speed alongside the download. It is in the contract information document you were sent when you signed up, and on the provider's own package page rather than the banner.
- Test it properly.Run the test on a device connected by ethernet, with nothing else in the house active. A speed test over wifi measures your wifi, and an upload test with a cloud backup running measures whatever is left.
- Compare against what you were sold, not against the download.An upload that is a tenth of the download is completely normal on part-fibre. An upload that is a tenth of your contracted upload is a fault.
- Work out whether it is actually limiting you.Video calls need surprisingly little — a couple of megabits per participant. Cloud backup of a large photo library, sending video files, or several 4K cameras uploading continuously are what genuinely need a big upload figure.
- If it matters, look at what is available at your address.Full fibre providers increasingly sell symmetric packages, where upload equals download. That is the only real fix for a genuine upload constraint. Check what is available at your postcode rather than assuming.
If it doesn't work
Upload has dropped compared with a few months ago
Cause: A line fault, or something in the house uploading constantly — Fix: Check for a cloud backup, a photo sync or a camera uploading. If the house is quiet and the upload is still down, report it with dated test results from an ethernet-connected device.
Video calls freeze when someone else is at home
Cause: The upload is being shared and it is the smaller number — Fix: Upload congestion is what breaks calls, not download. Prioritise the work device on the router, or pause backups during working hours.
Upload is fine on ethernet, terrible on wifi
Cause: A weak wifi link, which degrades in both directions — Fix: The wifi is the limit rather than the line. Move closer, change band, or wire the device.
Questions people ask
Is a slow upload the reason my video calls are bad?
Very often, yes. A call pushes your camera out continuously, so it depends on upload. But stuttering with plenty of upload headroom points at latency and jitter instead, which are different measurements.
Can I pay to increase just the upload?
Not usually as a separate item. Upload is set by the technology and the package, so increasing it means changing package or provider — and on part-fibre the ceiling may be fixed regardless of what you pay.
What upload speed do I actually need?
For calls and ordinary use, very little. For a household backing up phones and photos automatically while someone works from home, a genuinely constrained upload starts to hurt. Look at what is uploading, not at a rule of thumb.