Why is my upload speed so slow?
Your upload speed may be slow because your broadband plan provides limited upstream capacity, your Wi-Fi connection is weak, another application is using bandwidth, or your device or network equipment is restricting performance. The receiving server or application can also affect how quickly a file uploads.
Start by comparing your measured upload speed with the upload rate included in your internet package. Then test your connection under controlled conditions, preferably using Ethernet where supported.
The result helps you narrow down the problem:
| What you notice | What to investigate |
|---|---|
| Upload speed is consistently below your plan's expected rate | Broadband service, equipment or ISP |
| Ethernet performs better than Wi-Fi | Wireless signal or interference |
| Upload improves when other activities stop | Background transfers |
| Only one device is slow | Device, adapter or software |
| Speed test is good but file uploads are slow | Application or destination server |
Do not buy a new router or upgrade your package until you have identified a likely bottleneck.
How to test your upload speed properly
Before changing network settings, establish a reliable baseline. A single result may not represent your connection's normal performance.
Check the upload speed included in your internet plan
Find your package details through your ISP's website, customer account or service agreement. Look for the upload speed rather than relying only on the advertised download speed.
Some broadband packages provide different download and upload rates. Others offer similar capacity in both directions. Your result should be compared with the upstream rate specified for your particular service.
Also check whether your provider lists an advertised, estimated, typical or minimum speed. These terms can have different meanings depending on the provider and country.
Run an upload speed test under comparable conditions
Use the upload speed test to measure your connection's outgoing throughput.
For a useful baseline:
- Pause large file uploads, cloud backups and other major transfers temporarily.
- Use one connected device.
- Close applications that are actively transferring large amounts of data.
- Run the upload test and record the result.
- Note the time, device and whether you used Ethernet or Wi-Fi.
- Repeat the measurement to check whether the result is consistent.
The test measures performance toward its selected endpoint. It does not guarantee that every website or cloud-storage service will receive data at exactly the same rate.
Test at different times if performance changes
If uploads become slower during particular hours, repeat the test at different times of day while keeping the conditions as similar as possible.
Record the results rather than assuming that one evening slowdown proves your ISP is throttling your connection. Repeated measurements help distinguish a temporary fluctuation from a recurring performance problem.
Ofcom also recommends testing more than once because broadband speed can vary by time and day. See its broadband and Wi-Fi troubleshooting guidance.
Why is upload speed slower than download speed?
Upload and download speeds measure data moving in opposite directions. Download speed measures data received by your device, while upload speed measures data sent from your device toward a destination.
Your broadband plan may provide different capacity for each direction.
Does your broadband plan offer asymmetric speeds?
An asymmetric broadband connection provides different download and upload capacities. For example, a package might offer a higher download rate than upload rate because its service design allocates different capacity to each direction.
Other providers offer symmetric or near-symmetric packages, where the advertised upload and download rates are similar.
Check the actual package details before deciding that a lower upload result indicates a fault. A lower upload speed may be normal for your subscription.
Does your connection technology affect upload capacity?
Fiber, cable, DSL and fixed wireless services can have different upstream characteristics. However, you should not assume that every service using the same technology has an identical upload-to-download ratio.
The provider's network design, equipment, service configuration and package all matter.
For a broader explanation of upstream and downstream rates, read understanding Mbps.
How to find out what is limiting your upload speed
The most useful troubleshooting step is to compare results under controlled conditions. This helps you identify whether the limitation is within your home network, device, broadband service or destination application.
Compare Ethernet and Wi-Fi results
Run an upload test using Ethernet if your device supports a suitable wired connection. Then compare it with a Wi-Fi test on the same device under similar conditions.
A much better wired result suggests that the wireless connection may be limiting performance. Distance, walls, interference and device capabilities can all affect Wi-Fi.
However, Ethernet is not automatically faster in every situation. Its performance also depends on the network adapter, router ports, cable condition and negotiated link speed.
See Ethernet vs. Wi-Fi for a more detailed comparison.
Test another device on the same network
If possible, test another laptop or computer using the same connection method.
Use the results as diagnostic clues:
| Observation | What it may indicate |
|---|---|
| One device is slow, others perform normally | A device-specific issue |
| Multiple devices are slow over Wi-Fi but improve over Ethernet | A wireless limitation |
| Multiple wired devices have poor upload results | A shared equipment, service or ISP issue |
These observations narrow down the possibilities, but they do not independently prove the exact cause.
Check whether other uploads are running
Another device may already be uploading data while you run your test. Common examples include:
- Cloud backups and photo synchronization.
- Large file transfers.
- Video uploads.
- Shared work folders.
- Other computers sending files.
- Applications synchronizing data in the background.
Pause unnecessary transfers temporarily and repeat the test. If performance improves, identify which device or application was consuming upstream capacity.
Microsoft recommends avoiding other applications and network activity during large OneDrive transfers. Its guidance also explains that file size, computer performance, ISP upload limits and proximity to its servers can influence transfer time.
Read Microsoft's guide to maximizing upload and download speed.
Compare speed-test results with real file transfers
A speed test and a real file upload do not measure exactly the same activity.
A speed test transfers data between your device and its selected test endpoint. A cloud upload involves an application, the destination server, the route between them and the file-transfer process.
If your speed test is good but one service uploads slowly, try another destination or application. If the alternative performs normally, investigate the original service rather than immediately changing your broadband package.
What causes slow upload speed?
Several parts of the connection can restrict upstream performance. The following causes are worth investigating after establishing a reliable baseline.
Your internet plan has limited upload capacity
Your package may intentionally provide less upload capacity than download capacity.
This is especially important when comparing a test with a package marketed primarily around its download speed. Check the provider's stated upstream rate and determine whether it is sufficient for your activities.
If your connection consistently performs within its package's expected upload range, a different router may not make the broadband service itself faster.
Weak Wi-Fi or wireless interference
Wi-Fi performance can decline when your device is far from the router or separated by walls and other obstacles.
Nearby wireless networks and electronic equipment may also affect the wireless environment. Your connected device's wireless adapter and supported features influence the result as well.
Try testing close to the router. If upload performance improves, investigate the router's placement, frequency band and interference.
For more detailed wireless improvements, see how to improve Wi-Fi speed at home.
Background applications are using upload bandwidth
Cloud synchronization, automatic backups and file transfers can consume upstream capacity without being obvious.
For example, a computer may synchronize documents while another device uploads photos. During these transfers, less upstream capacity may be available for a new upload or video call.
Check active applications and connected devices. Pause unnecessary uploads temporarily, then repeat your measurement.
Your router, modem, Ethernet port or network adapter is limiting performance
A hardware limitation can restrict performance even when the broadband package offers higher speeds.
Check:
- Whether your router's WAN and LAN ports support the required link rate.
- Whether the Ethernet connection negotiates at an expected speed.
- Whether the cable or connector is damaged or poorly seated.
- Whether the network adapter supports the connection's capabilities.
- Whether the modem or ONT reports an equipment or service problem.
For example, a Gigabit-capable Ethernet connection that negotiates at 100 Mbps may limit the local link. Intel's Ethernet link-speed troubleshooting guide explains how to check this condition.
Do not assume you need a more expensive cable or router before checking the actual negotiated link speed and equipment capabilities.
Network congestion or peak-time variation
Your upload performance can vary when other devices or users share the available network capacity.
A slowdown that regularly appears at busy times may indicate congestion within your home network or the provider's access network. It can also coincide with other activity, such as cloud synchronization.
Repeat your tests at different times, using comparable conditions. A recurring pattern provides better evidence than one low result.
The VPN or application is affecting the transfer
A VPN changes the route through which your traffic travels and may introduce additional processing. Depending on the VPN server, route and equipment, this can affect transfer performance in either direction.
An application may also impose its own upload limit or behave differently from a speed-test service.
When safe and permitted, compare the same transfer with the VPN enabled and disabled. Restore your intended security configuration afterward. Do not treat a VPN as a guaranteed way to increase upload speed or bypass an assumed ISP restriction.
How to increase upload speed based on the cause
The right fix depends on the bottleneck you identified. Start with changes that are free and reversible.
Pause unnecessary uploads and synchronization
Temporarily pause large backups, file transfers and synchronization tasks. Check other devices that share the connection, especially computers and phones that upload photos or videos automatically.
Where possible, schedule large backups for less disruptive periods. Do not permanently disable important backups simply to improve a speed-test result.
Switch to Ethernet or improve your Wi-Fi connection
If Ethernet performs better, use a suitable wired connection for fixed devices that need consistent performance.
If Wi-Fi is the limiting factor, improve router placement, reduce obstacles and investigate wireless interference. Test again in the rooms where you normally upload files.
Check your router and network hardware
Check your router's connection status, supported port speeds and manufacturer instructions. Inspect Ethernet cables and connectors, and confirm the negotiated link speed where your operating system provides that information.
Keep firmware updated through the manufacturer's official process. Avoid changing advanced settings or resetting equipment without understanding the consequences.
Review device, VPN and application settings
Check for applications using network capacity in the background. Update network drivers through the computer or adapter manufacturer's official support channel.
If one application uploads slowly, compare another destination and check whether that application has an upload limit. If a VPN appears to affect performance, perform a controlled comparison and restore your preferred security settings.
Contact your ISP if wired results remain consistently low
If several devices show unexpectedly poor upload performance over suitable wired connections, investigate the broadband service.
Check provider service notices and contact support with your repeatable test results. Ask them to review the package's upload rate, equipment status, provisioning and any reported line or network faults.
Why does upload speed slow down at night?
Upload speed may change in the evening or during other busy periods because several users and devices share network resources.
The cause might be activity within your home, such as cloud backups or file transfers, or conditions elsewhere in the provider's network. Your wireless environment may also become busier when more nearby networks are active.
To investigate:
- Run tests at different times.
- Keep the device and connection method consistent.
- Pause competing uploads before testing.
- Record the time and results.
- Check whether the same pattern occurs over Ethernet.
A recurring slowdown is worth investigating, but an evening result alone does not prove deliberate ISP throttling.
When should you contact your internet provider?
Contact your ISP when repeated tests suggest that upload performance is below what your package should provide, especially when the problem occurs across multiple devices using suitable wired connections.
What evidence should you collect before contacting support?
Prepare the following information:
- Your broadband package and stated upload rate.
- Several upload-test results.
- The date and time of each test.
- Whether you used Ethernet or Wi-Fi.
- Which device you tested.
- Whether background uploads were paused.
- Whether another device showed the same problem.
- Any relevant router, modem or ONT status messages.
What should you ask your ISP to check?
Ask the provider to confirm the upload rate associated with your package and investigate whether there are equipment, provisioning, access-line or network faults.
Avoid starting with an accusation of throttling. Give the provider repeatable results and explain the conditions under which the problem occurs.
Complaint rights, speed guarantees and escalation procedures vary by country. Follow the process provided by your own ISP and the relevant local regulator.
How to confirm your upload speed has improved
Repeat the original upload test using the same device, test endpoint and connection method. Keep other network activity similar so that the comparison is meaningful.
Compare the new results with your baseline rather than relying on one unusually high measurement. If you changed several settings at once, you may not know which change helped.
For a final check, upload a file to the application or service that originally caused the problem. A repeatable speed-test improvement is useful, but the actual transfer should also be checked.
Run another upload speed test to compare your results. For broader slowdowns that are not limited to uploads, see why is my internet so slow?.