How to Get Phantom Membranes in Minecraft

Guide Java Bedrock

Quick answer: Kill phantoms: each drops 0-1 membranes (up to 4 with Looting III), only when killed by a player. Phantoms spawn after 3 in-game days without sleep. Membranes repair elytra in an anvil (25% durability each) and brew Slow Falling potions.

What you need

No bed for 3 in-game days (to spawn phantoms)
Smite sword or bow
Looting III sword (optional, up to 4 membranes)
Anvil for elytra repairs

Step by step

Trigger phantom spawns: stay awake for 3 straight in-game days (about an hour). Phantoms then spawn at night above you in the Overworld, diving in waves - more the longer you go without sleep.
Fight smart: phantoms swoop down in straight dives. Stand in the open at night, hit them as they pass, and collect the drops - 0-1 membrane per phantom (50% by default, 75% with Looting I, 87.5% with II and 91.67% with III).
Or sleep with a cat: tamed cats have a 70% chance of bringing a morning gift when you wake from a bed, and 3.22% of gifts are a phantom membrane - a passive, if slow, source.
Sleep regularly to avoid them: one night in a bed every 3 days resets the insomnia timer and phantoms never come - but then no membranes either.
Repair your elytra: combine a damaged elytra with a phantom membrane in an anvil to restore 108 durability (25%) per membrane, keeping every enchantment. Four membranes take an elytra from nearly broken to full.
Brew Slow Falling: phantom membrane + awkward potion makes a Potion of Slow Falling.

Java vs Bedrock

Both editions spawn phantoms above a player who has not slept for at least 3 in-game days, but the spawning mechanics differ between Java and Bedrock.

Versions: Phantom membranes are used to repair elytra in an anvil and to brew Slow Falling potions.

Frequently asked questions

What drops phantom membranes?

Phantoms - 0-1 membranes per kill, up to 4 with Looting III, only if the player kills them. Tamed cats also rarely gift one after you sleep (3.22% of cat gifts).

Why aren't phantoms spawning?

You must skip sleep for 3 full in-game days. Phantoms only spawn at night above players with insomnia, in the Overworld, with sky access. Sleep resets the counter.

How many membranes do I need to repair an elytra?

Each membrane restores 108 durability (25% of total) in an anvil, so 4 membranes fully repair a nearly broken elytra - with all enchantments intact.

What is phantom membrane used for?

Repairing elytra in an anvil and brewing Potions of Slow Falling from awkward potions.