Why is my upload so slow? Causes and fixes

Uploads are usually slow for one of three reasons: your internet plan has a much lower upload speed than download speed, your Wi-Fi is losing speed between the device and the router, or something else is already using your upload bandwidth, such as a cloud backup or a video call. The good news is that most of these can be checked in a few minutes and fixed without changing provider.

Below, the ten most common causes in order of likelihood, a step-by-step diagnosis, and practical ways to make large uploads faster and more reliable.

Why is upload speed slower than download speed?

Most home connections are built that way. Cable and DSL lines dedicate most of their capacity to downloads, because that is what streaming and browsing need. The US Federal Communications Commission says it plainly in its consumer guide: applications would work best with equal upload and download speeds, “but service providers generally don’t offer that option”. Its own broadband benchmark, maintained in August 2026, is 100 Mbps down and 20 Mbps up.

Fibre to the home is often symmetric or close to it, which is why France, with widespread fibre, shows upload speeds near its download speeds. If your plan is asymmetric, no setting will make uploads faster than the line allows; the fixes below help you get the full speed you pay for.

The 10 most common causes of slow uploads

1. Your plan’s upload speed is low. Check the typical upload speed on your contract or broadband label; in the US, providers must state it.
2. Wi-Fi. Distance, walls and interference cut speed. Ofcom, the UK regulator, notes that Ethernet cables often give a better connection than Wi-Fi, and that brick walls and devices such as microwaves or baby monitors can degrade the signal.
3. Cloud backups and sync. iCloud, Google Photos, OneDrive or Dropbox may be uploading in the background and using all your upstream bandwidth.
4. Other people and devices. Video calls, game streams, security cameras and another family member’s uploads all compete for the same upload capacity.
5. A VPN. Traffic is encrypted and routed through a remote server, which adds overhead and distance.
6. Bufferbloat. When the upload link is saturated, some routers queue too much data, which makes everything feel sluggish. The internet engineering community has documented this “at the consumer edge” and developed queue management such as CoDel and FQ-CoDel to fight it.
7. Mobile data. Median mobile upload speeds in September 2026 were 13.99 Mbps globally and around 10 Mbps in the US, UK and France, according to Ookla.
8. An old router or cable. Outdated Wi-Fi standards or damaged cables cap speeds well below your plan.
9. The device itself. Low Power Mode, a laptop going to sleep, or a browser tab in the background can slow or pause uploads.
10. Data caps or traffic management. The FCC notes that some providers limit the total amount of data you can upload and download each month.

How to diagnose a slow upload, step by step

1. 1

   Step 1

   Run a speed test on the uploading device

   Note the upload figure. Compare it with the upload speed in your plan.

2. 2

   Step 2

   Repeat with a cable

   Connect the computer to the router with Ethernet and test again. If the result jumps, Wi-Fi is the bottleneck.

3. 3

   Step 3

   Pause everything else

   Stop cloud backups, close video calls and ask others to pause big uploads. Test again.

4. 4

   Step 4

   Turn off the VPN

   If your policy allows, test without it to see how much it costs you.

5. 5

   Step 5

   Test at another time

   If speeds are much lower in the evening, congestion at your provider is likely.

6. 6

   Step 6

   Restart the router

   It clears stuck sessions and sometimes oversized queues. If nothing helps, contact your provider with your test results.

How to make large uploads faster

• Use Ethernet for big transfers, or move closer to the router.
• Schedule uploads at night, when networks are quieter and nobody else is on a call.
• Pause cloud sync during the upload and resume it afterwards.
• Keep the device awake and plugged in; change the sleep settings for long transfers.
• Do not compress media just to save time: zipping photos or videos barely reduces their size; see should you zip files before sending?.
• Upload once, share many times: a transfer link means you upload a file once, whatever the number of recipients.

What your upload speed means for real files

The full table, up to 1 TB, and the formula behind it are in our article how long does it take to upload large files?. If your units are fuzzy, the file size guide explains why 100 Mbps means about 12.5 MB per second.

Why a browser upload can stall, and how Transfr handles it

On Transfr, files are uploaded in chunks, several in parallel, and an interrupted chunk is retried automatically when the connection comes back; the upload pauses while you are offline instead of failing. If the page is reloaded, a large file can be resumed by adding the same file again (for transfers without end-to-end encryption). Even so, a closed tab or a sleeping laptop stops the upload, so keep the page open until it completes.

Slow uploads from a phone

Phones add their own bottlenecks: mobile upload speeds are much lower than fixed ones, and phones aggressively save battery. Connect to Wi-Fi, keep the browser in the foreground with the screen on, plug in the charger and turn off Low Power Mode or battery saver during long uploads. Check, too, that photo backup apps are not uploading your whole gallery at the same time. Our guides to sending large files from iPhone and to sending large files from Android cover the device-specific settings.

Slow uploads at the office or school

Shared networks have their own reasons: dozens of people on the same line, firewalls or proxies that inspect traffic, and sometimes rules that slow down or block uploads to unknown services. If uploads are fast at home and slow at work, talk to your IT team before trying workarounds; they may have an approved tool or be able to allow the one you need. For big deliveries, uploading from home in the evening is often the pragmatic answer.

When should you upgrade your plan?

If you regularly send large files and your tests on a cable match your plan’s upload speed, the line itself is the limit. Fibre plans with symmetric or high upload speeds make the biggest difference for video professionals, photographers and anyone who backs up a lot. Before upgrading, check what upload speed your provider actually guarantees, not just the headline download figure. For a broader view of the options for sending big files, see how to send large files, and for very large deliveries, our pages on sending 10 GB and 100 GB.