How to Clear LINE App Cache on iPhone: Free Up 20GB Without Losing Chat History (2026)

If your iPhone is displaying the dreaded 'iPhone Storage Almost Full' alert, the culprit might not be your 4K video roll or mobile games. For hundreds of millions of users across Japan, Taiwan, Thailand, and Southeast Asia, the primary memory drain is quietly sitting inside a single green icon: the LINE messenger app. Over months and years of daily communication, LINE's local database silently stockpiles gigabytes of uncompressed preview thumbnails, cached group video snippets, audio notes, sticker asset packages, and LINE VOOM stream preloads. It is shockingly common for a standard LINE installation to swell from 300 megabytes upon initial download to over 25 gigabytes of hidden storage bloat. Fortunately, you can reclaim this space in under five minutes without losing your valuable chat history or important work conversations.

The critical anxiety preventing most iPhone users from decluttering LINE is the fear of accidental data loss: will clearing cache erase precious family photo albums, delete text messages, or log you out of your account? The answer is an absolute no—provided you use the correct internal settings menu. In this technical walkthrough, we break down exactly how LINE organizes its data architecture on iOS, how to safely flush temporary cache files, how to resolve stubborn 'System Data' (Other) bloat, and how paired storage utilities like Clearly Smart Storage Cleaner help you maintain a clutter-free device effortlessly.

Quick Answer: The 4-Step Method to Clear LINE Cache Safely

To clear LINE cache without touching your chat messages or account credentials, follow this exact sequence directly within the LINE app:

1. Open LINE Settings: Tap the Home tab (house icon) at the bottom left, then tap the Gear icon (Settings) in the top right corner.
2. Navigate to Chat Data: Scroll down and select Chats (トーク), then scroll to the bottom and tap Delete data (データの削除).
3. Inspect Cached Data: LINE will calculate your storage usage. Locate the Cached data (キャッシュ) line item. You will typically see between 2 GB and 18 GB listed here.
4. Confirm Deletion: Tap the red Clear (削除) button next to Cached data. Confirm the prompt. Your text chats, voice notes, stickers, and contact lists will remain 100% intact.

Anatomy of LINE Storage Bloat: Where Do the Gigabytes Actually Go?

To understand why LINE expands so aggressively, we must examine the Apple File System (APFS) sandbox container allocated to the app on iOS. Unlike desktop messaging clients that query remote servers on demand, LINE aggressively caches rich media locally to deliver instantaneous rendering when scrolling through active group chats:

Why Clearing Internal Cache Doesn't Fix 100% of 'System Data'

Many users clear LINE's internal cache, open iOS Settings > General > iPhone Storage, and are dismayed to see that 'System Data' or LINE's app footprint has barely shrunk. This occurs due to Apple's SQLite Write-Ahead Logging (WAL) and orphaned temporary sandbox directories. When you save photos from LINE group chats to your iOS Photos library, duplicate copies are frequently created in temporary storage caches, consuming double space. Furthermore, shared videos sent through LINE chats linger in hidden APFS snapshots until explicitly indexed and purged.

To achieve a true deep clean, pair your LINE maintenance with Clearly Smart Storage Cleaner. Clearly uses machine learning to scan your entire media library for redundant duplicates, compressed screenshots, and heavy WhatsApp/LINE downloaded video duplicates, reclaiming 10 to 30 GB of storage with automated precision. For camera roll photo triage, Swipe Photo Cleaner provides a smooth Tinder-style swipe interface to rapidly review and delete unnecessary screenshots and duplicate meme uploads.

The Nuclear Option: How to Reinstall LINE Without Losing Data

If your LINE application container still reports 15+ GB despite clearing the cache, your local SQLite database is severely fragmented. The definitive solution is an iCloud Chat Backup followed by a fresh installation:

1. Execute Cloud Backup: Go to LINE Settings > Chats >Chat history backup (トークのバックアップ) >Back Up Now. Verify that your iCloud backup finishes successfully with today's timestamp.
2. Confirm Account Credentials: Ensure your phone number, email address, and Apple ID / password are bound in LINE Settings >Account.
3. Delete and Reinstall: Delete the LINE app from your home screen. Download LINE anew from the App Store.
4. Restore Chats: Log in and tap Restore chat history during setup. Your app size will drop from 20GB to approximately 800MB while preserving every message thread.