Diskio

Disk & SSD Speed Test

Version 3.1.0 · Made for iPhone

Know your storage.
See every run.

Measure sequential read and write speeds on your iPhone or a compatible external drive. See median speeds, ranges and every individual run.

iOS 16.0+1, 3 or 6 runsExternal drives6 languages

View on the App Store Explore the app

Diskio’s dark result screen showing median read and write speeds, stability and all six individual runs — Diskio · Example results

A clearer storage benchmark

Understand the result behind the speed.

More than one number

Choose 1, 3 or 6 runs. Repeated tests show median read and write speeds, minimum and maximum values, and the result of every run.

Check result stability

With 6 runs, assess read and write consistency separately over the last five. Open the explanation to see how each assessment is made.

Test your whole setup

Choose internal storage or a compatible, writable external drive through Files. Your device, cable and connection all contribute to the result.

Choose your test

Set a 1–5 GiB file and a 1, 2, 4, 8 or 16 MiB block. Start with the defaults: 6 runs, a 1 GiB file and a 2 MiB block.

Follow every phase

Watch each write and read phase fill its own progress arc. Low-space messages help you understand when storage conditions may affect a test.

Keep the full picture

Share a result card with the report, test settings and stability assessment. Light and dark appearances, larger text and Reduce Motion are supported.

Take a closer look.

The current app, from the first measurement to the shared report. Select an image to view it full size.

Diskio showing median write and read speeds after six runs — Read & write speedsOpen full size

1 of 6

New in 3.1.0

Room to unfold.

On iPhone Duo, controls and results get their own space. The layout adapts to the display and fold, while narrow Split View windows stay compact.

Your completed report and open panels stay available as the layout changes. Independent scrolling keeps long reports accessible, and a new test brings its progress back into view.

Diskio in dark appearance on the unfolded iPhone Duo simulator, with the result summary on the left and all six individual runs on the right — Duo simulator capture. The displayed speeds illustrate the layout and are not device performance claims.

Know what you’re measuring.

Diskio measures sequential file reads and writes in MB/s. Write timing includes the final filesystem synchronization. Results depend on your device, drive, connection, free space and test settings.

The stability assessment adapts numerical criteria from SNIA SSS PTS. It does not establish full SNIA compliance, drive health or sustained performance. The revised method in version 3.0 means results may differ from older versions.

Ready for your next test.

Select internal storage or a compatible external drive.
Choose your settings and keep Diskio open during the test.
Review the report or share your results.

Allow enough free space for a temporary test file. External storage must be accessible and writable through Files.

What’s new in Diskio

3.1.0

An adaptive Duo layout

Dedicated space for controls and results, compact narrow windows, and better handling when leaving or returning to the app.

3.0.1

Hallo, Diskio.

German across settings, results and shared reports, with improved localized permission and storage-space messages.

3.0

A more complete report

A redesigned interface and icon, revised measurements, repeat runs, stability assessments, clearer progress and low-space warnings.

See what your storage can do.

Diskio for iPhone · iOS 16.0 or later

View on the App Store

Available in English, German, Japanese, Simplified Chinese, Spanish, Ukrainian.

Know your storage.See every run.