Quick answer: Start with the easy wins: clear the Screenshots album, merge Duplicates (under Utilities), and delete long videos you don't need. Then empty Recently Deleted. Don't try to sort every photo; keep one "Keep" album and move non-photos out of your camera roll.
Written for iOS 18 and iOS 26. Menu names can differ slightly on older versions.
Cleaning a camera roll of 20,000 photos in one go never happens. A few targeted passes, done in the right order, clear most of the clutter in under an hour.
Step 1: Clear screenshots first
Screenshots are where most of the junk lives: old codes, deliveries, memes. Deleting them feels low-risk.
Photos›Collections›Media Types›Screenshots
Select and delete in bulk; on iOS 17 and earlier it's under Albums. How to delete all screenshots at once.
Step 2: Merge duplicates
Open Utilities → Duplicates. iPhone finds identical photos and near-identical copies and lets you merge each set, keeping the best quality version.
Step 3: Find the big videos
Videos take far more space than photos. Open Media Types → Videos and delete long clips you'll never watch again. Screen recordings (also under Media Types) are often forgotten and large.
Step 4: Empty Recently Deleted
Deleted items stay for 30 days. To free the space now, open Utilities → Recently Deleted, unlock it, and choose Delete All.
Step 5: One "Keep" album, not twenty
Instead of sorting everything, make one album for photos you'd be upset to lose and add to it as you go. Everything else can stay in the general library without stress.
Step 6: Let iCloud handle storage
If storage is the real worry, turn on iCloud Photos with Optimize iPhone Storage: full-size originals live in iCloud and smaller versions stay on your phone. It needs enough iCloud storage for your library.
Keep it from filling up again
Most clutter is information that never needed to be a photo: receipts, tickets, codes. Save those somewhere searchable instead, like Snugit or a note, and your camera roll stays for actual photos.
Get Snugit and keep receipts, codes and tickets out of your camera roll.