Sequential read speed for video editing

Your video editor pauses while scrubbing, playback stutters, or a second camera angle makes the timeline less responsive. The storage drive may be struggling to deliver footage quickly enough, but a low benchmark result does not automatically mean the drive is failing.

Sequential read speed measures how quickly a drive can read a large run of data. That is useful for video files, which are usually read in long streams. The Storage Test checks large-file disk speed in your browser, giving you a starting point for comparing it with your editing workload.

Check the drive's sequential read speed

1. Open the Storage Test on the computer and drive you want to check. If the browser asks for storage access, allow it so the test can run.
2. Close file transfers and other tasks that are actively reading or writing large amounts of data. Keep the computer plugged in if it is a laptop.
3. Run the test and note the large-file read result, including its unit. MB/s means megabytes per second. The test also reports other storage measures, so do not confuse a small-write result with sequential reading.
4. Repeat the test once under the same conditions. If you are comparing an internal drive with an external one, test each separately and note how it is connected.

A browser benchmark is a useful comparison, not a complete simulation of your editing software. Results can vary with the browser, other activity, temporary browser storage, and the drive connection. For more context, see why storage benchmarks vary between browser runs.

What the result means

The read speed is comfortably above your footage needs

The drive is probably not the first limit to investigate for a single stream of that footage. Check the timeline with your usual project, though. Multiple camera angles, effects, high-resolution previews, and background tasks can increase the work beyond one file stream.

The result is close to the footage's data rate

The drive may have little spare capacity for overhead or extra streams. Convert the footage bitrate from megabits per second to megabytes per second by dividing by 8. For example, 200 Mbps is 25 MB/s. If you play two such streams at once, their combined data rate is about 50 MB/s before overhead. Aiming for roughly twice that combined rate gives useful headroom, but it is a practical estimate, not a guaranteed requirement.

Footage bitrate can change from moment to moment, especially with variable-bitrate recording. Add together the rates of simultaneous source clips rather than looking at only one clip. Do not treat this estimate as a promise that the editing software will play smoothly, since decoding and effects also use the computer's processor and graphics hardware.

The result is much lower than your estimated needs

That points to storage as a possible bottleneck, especially if the timeline stutters more when you add clips or scrub through high-bitrate footage. Retest after stopping backups, downloads, or file copies. A slow result can also come from a cable, hub, port, or browser conditions rather than a failing drive.

The result changes a lot between runs

Changing results can indicate background activity, caching, or normal variation in a browser test. Compare repeated runs made with the same browser and setup. A single unusually low number is not enough to diagnose a drive fault.

How to improve or retest the result

1. Stop other storage activity. Pause large downloads, backups, file copies, and exports, then rerun the test. These tasks compete for drive access and can reduce the speed available to your project.
2. Check the power mode. On Windows 11, open Settings › System › Power & battery and review Power mode. On a Mac, check System Settings › Battery and test while connected to power if practical. Power-saving behavior can affect some computers, so compare like with like.
3. Check available space. A nearly full drive may have less room for temporary files and editing caches. On Windows 11, open Settings › System › Storage. On macOS, open System Settings › General › Storage. Keep working room available, especially on the drive that holds project media and cache files.
4. Connect an external drive directly. If you use a hub or dock, connect the drive to a computer port and test again. Try another cable or port if the speed remains low. A connector that fits does not guarantee the same data rate across cables and ports.
5. Compare a local copy of the footage. If source clips live on a network share, cloud-synced folder, or removable drive, copy a sample to the computer's internal storage and test playback. If the local copy plays smoothly, investigate the original connection or storage location.
6. Restart and retest. A restart clears some stuck background activity. Use the same browser and test setup afterward, and compare more than one run before drawing a conclusion.

When the drive may be the problem

Suspect the drive when repeated read results stay low, editing performance worsens on that drive, and the same project behaves better from another known-good drive. Look for other warning signs too, such as disconnects, read errors, files that fail to open, or unusual mechanical noises from a hard drive. Back up important footage before running further tests if you see errors or disconnects.

A browser test cannot inspect a drive's complete health or prove that every sector is reliable. Check the computer's built-in drive health information or ask a repair technician if errors continue. Replace a drive that is unreliable or failing, and do not rely on a higher benchmark score as a repair.

Why sequential speed is not the whole story

Sequential reads are a good fit for long video streams, but editing also involves many smaller tasks: opening project files, loading thumbnails, saving changes, and managing cache data. These can depend more on small-write or random-access performance than on the large-file read number. The Storage Test includes other measures for that reason, but neither a browser test nor a single score reproduces every editing workflow.

Storage Test uses temporary browser data rather than your project footage. Use your editing software's playback and export behavior as the final check for the project you actually work on.