Quick Answer

You can find your iPhone’s build number right inside the Settings app—no computer needed.

Step-by-Step: Where to Find the Build Number on iPhone

1. Open Settings

  • Tap the Settings app on your Home Screen.

2. Go to General > About

  • Scroll down and tap General.
  • Then tap About near the top.

3. Tap the iOS Version

  • You’ll see a line labeled iOS Version (e.g., “17.5”).
  • Tap that version number once.

4. See the Build Number

  • After tapping, the version line expands to show the build number (for example, 21F90 or 21F101).
  • This build identifier is more precise than the public version and is what Apple uses internally.

Tip: If you don’t see the build appear after tapping, make sure you’re tapping directly on the version number text, not just the label.

Alternative: Using a Computer (if needed)

If your iPhone screen is damaged or you prefer using a computer:

  1. Connect your iPhone to:
    • a Mac (Finder on macOS Catalina or later), or
    • a PC/Mac with iTunes or the Apple Devices app.
  1. Select your device in Finder/iTunes.
  2. On the Summary (or General) tab, click the version number—it will toggle to show the build number as well.

Why the Build Number Matters

  • Troubleshooting: Some bugs or fixes are tied to specific builds, not just iOS versions.
  • Support & Betas: When talking to Apple Support or testing beta software, the build number helps pinpoint exactly what you’re running.
  • Security & Updates: Certain enterprise or developer workflows require the exact build for compatibility checks.

TL;DR

Settings → General → About → tap the iOS Version → build number appears.

Information gathered from public forums or data available on the internet and portrayed here.