Upload Speed Test
Upload speed — the half of the connection that breaks calls and backups.
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Measured against one Cloudflare edge with 4 parallel streams. A commercial speed test picks a server from a large fleet, often on your own provider's network — this measures the path to a CDN, which is closer to what a real download does and reads lower than the figure your provider quotes.
How this check works
Four parallel streams post one-megabyte bodies for eight seconds, and the steady-state rate is taken after the ramp is discarded. Upload is worth measuring separately because home connections are asymmetric by design — frequently by a factor of ten or more — and it is the direction that limits the things people notice: a video call sends as much as it receives, a cloud backup is entirely upload, and a large attachment leaves at this speed rather than the one on the box.
What the results mean
- Asymmetry
- Most home connections have far less upload than download. It is a design decision in the access technology rather than a fault.
- HD video call
- Wants around 4 Mbps in each direction. A connection with 2 Mbps of upload cannot hold one however fast the download is.
- Ramp discarded
- Slow-start affects uploads exactly as it does downloads, and averaging over it understates the line.
- What saturating upload does
- Filling the upload queue delays acknowledgements for downloads too, which is why a backup can make everything else feel slow.
Common problems and fixes
- My upload is a tenth of my download
- That is normal for cable and most fixed-wireless connections. Fibre is usually symmetric or close to it, and it is the main practical difference between them.
- Everything slows down when I upload something
- A saturated upload delays the acknowledgements downloads depend on. That is bufferbloat, and the bufferbloat test measures how bad it is on your line.
- Video calls freeze when I share my screen
- Screen sharing multiplies upload demand. Compare this figure against the platform's stated requirement for sharing rather than for a plain call.
Frequently asked questions
Why is my upload speed so much slower than my download?
Because most access technologies are asymmetric on purpose. Cable and DSL allocate the bulk of their capacity downstream on the assumption that people consume more than they send, and a ten-to-one ratio is ordinary. Fibre is usually symmetric, which is the practical difference people notice when they switch.
How much upload do I need for video calls?
Around 4 Mbps for an HD call, and appreciably more if you share your screen or run several calls in a household. Upload is the direction that limits calls far more often than download, and it is the number worth checking before blaming the software.
Why does uploading slow down everything else?
Downloads depend on small acknowledgement packets travelling upstream. When the upload queue fills, those acknowledgements wait in it, so downloads stall too. That is bufferbloat rather than a bandwidth shortage, and queue management on the router fixes it.