hdiutil convert ~/Desktop/BigSur.dmg -format UDTO -o ~/Desktop/BigSur.iso
While macOS has moved on to Ventura and Sonoma (and beyond), the macOS Big Sur ISO 2021 remains a critical tool for:
Final Recommendation: Do not download shady ISOs from random forums. Use the Terminal method above to convert Apple’s official Install macOS Big Sur.app into a pristine ISO. It takes 30 minutes, but you get a secure, bootable, 2021-perfect image that will work on VMware, VirtualBox, or a USB drive. macos big sur iso 2021
Search for “macOS Big Sur ISO 2021” safely: Create, don’t pirate.
Need help booting your ISO? Leave a comment below (or check r/macOSVMs on Reddit for archived 2021 threads). hdiutil convert ~/Desktop/BigSur
Result: A clean, official BigSur.iso (approx 13GB) on your Desktop, ready for 2021-era virtualization.
Check the file size and integrity:
ls -lh ~/Desktop/BigSur.iso
# Should be ~12–14 GB
shasum ~/Desktop/BigSur.iso
Before we proceed, a strict warning: Avoid untrusted “pre-made” macOS Big Sur ISO files from torrent sites or random blogs.
The Golden Rule: Never trust a pre-made ISO. Always create your own using the official Apple installer. Final Recommendation: Do not download shady ISOs from