How to Unlock the True Pacifist Ending in Undertale: All Requirements and Steps

To unlock the True Pacifist ending in Undertale, complete a Neutral ending, keep 0 EXP, befriend Papyrus, Undyne, and Alphys, and finish the True Lab. If your Neutral run was already pacifist, reload your existing SAVE instead of restarting.

Key Takeaways

• Keep LV 1 and EXP 0: do not kill regular monsters during the run.
• Complete a Neutral ending first: True Pacifist cannot fully unlock before Undertale registers a Neutral completion.
• Befriend Papyrus, Undyne, and Alphys: their friendship events are required for the final route.
• Complete the True Lab: this unlocks the path to the True Pacifist ending.

What Are the Requirements for the True Pacifist Ending?

The True Pacifist Route has several conditions, and simply sparing the major bosses is not enough. Your actions throughout the game determine whether the later friendship events become available.

Requirement	What You Need to Do
EXP	Stay at 0 EXP
LV	Remain at LV 1
Neutral ending	Complete at least one Neutral ending
Papyrus	Spare and befriend him
Undyne	Spare her, give her water, then complete her hangout
Alphys	Deliver Undyne’s Letter and complete Alphys’s date
True Lab	Find the four keys and restore the generator
Final route	Continue through New Home after the True Lab

If you accidentally kill a monster but have not saved afterward, reload your previous SAVE. If you gained EXP and no longer have a SAVE from before the kill, you must reset the run to qualify for True Pacifist.

Step 1: Finish Every Battle Without Killing Monsters

Your most important rule is simple: do not gain EXP.

Regular encounters should be resolved through ACT, MERCY > Spare, or Flee when available. Some enemies require specific ACT combinations before their name turns yellow and they can be spared.

Using the FIGHT command does not automatically destroy the route. What matters is whether the enemy actually dies and awards EXP. For the safest playthrough, however, use ACT and MERCY whenever possible.

Your status should remain:

• LV: 1
• EXP: 0

This rule applies throughout the main route.

Step 2: Spare Toriel

During the battle with Toriel in the Ruins, repeatedly choose MERCY > Spare.

It may initially appear that sparing her is doing nothing. Keep selecting Spare rather than attacking her. Eventually, Toriel will end the battle and allow you to leave the Ruins.

Killing Toriel awards EXP and prevents that SAVE from qualifying for True Pacifist unless you reload a SAVE from before the fight.

Step 3: Spare and Befriend Papyrus

When you fight Papyrus in Snowdin, survive his attacks without killing him and choose Spare when the option becomes available.

After the battle:

1. Return to Papyrus’s house in Snowdin Town.
2. Talk to Papyrus outside his house.
3. Enter the house and begin his date or hangout event.
4. Complete the event before continuing toward the later friendship requirements.

The exact dialogue choices during the event do not prevent you from befriending Papyrus.

Papyrus’s friendship is required before you can properly complete Undyne’s friendship event.

Step 4: Spare Undyne and Give Her Water

The encounter with Undyne works differently from most boss fights. You eventually escape rather than ending the battle with a normal Spare command.

During the chase:

1. Use Flee whenever your SOUL becomes red and the option is available.
2. Continue running toward Hotland.
3. Wait until Undyne collapses from the heat.
4. Take water from the nearby water cooler.
5. Pour the water on Undyne.

Do not skip the water.

Giving Undyne water is required for her later friendship event. If you leave her after she collapses, you can lock yourself out of the True Pacifist progression on that run.

Step 5: Complete Undyne’s Hangout

After befriending Papyrus and helping Undyne in Hotland, return to Undyne’s house in Waterfall, near Napstablook’s home.

Papyrus should be waiting outside.

1. Talk to Papyrus.
2. Enter Undyne’s house.
3. Complete the cooking and hangout sequence.
4. Continue through the story normally afterward.

Your individual dialogue choices during the hangout do not ruin the True Pacifist Route.

The important requirement is completing the event itself.

Step 6: Finish the Mettaton EX Battle Peacefully

Continue through Hotland and the CORE until you reach Mettaton EX.

This battle uses a ratings system. Instead of killing Mettaton, increase the audience rating until the fight ends peacefully.

Useful ways to raise ratings include:

• Using ACT commands that entertain or impress the audience.
• Using certain items that affect the ratings system.
• Taking damage in specific situations, which can also increase ratings.
• Performing actions that create dramatic or entertaining moments.

Shooting Mettaton’s heart during attack phases can help end certain attack sequences sooner, but it is not itself the main method for increasing ratings.

The peaceful route ends when the ratings reach 10,000 after Mettaton has lost his arms and legs, or 12,000 if he still has his legs.

Once Mettaton EX has been dealt with peacefully, continue toward New Home.

Step 7: Complete a Neutral Ending

A Neutral ending must be registered before the True Pacifist Route can fully unlock.

Continue through New Home, confront Asgore, and proceed through the events involving Flowey/Omega Flowey.

After completing the Neutral ending, load your SAVE again.

If you followed the pacifist requirements and still have 0 EXP / LV 1, you normally do not need to restart Undertale. Your existing SAVE remains usable for the additional True Pacifist events.

This is one of the most commonly misunderstood parts of the route: a first pacifist-style playthrough initially reaches a Neutral ending, then expands into True Pacifist after reloading.

Step 8: Get Undyne’s Letter

After the Neutral ending has been completed and the required friendships are in place, reload your SAVE and backtrack away from the endgame area toward MTT Resort/CORE.

Undyne will contact you about delivering something to Alphys.

Then:

1. Travel back to Snowdin.
2. Find Undyne outside Papyrus’s house.
3. Talk to her to receive Undyne’s Letter.
4. Return to Alphys’s Lab in Hotland.

If your inventory is full, make room and speak to Undyne again.

If you deliberately discard the original letter, Undyne can provide Undyne’s Letter EX, which cannot be discarded.

Step 9: Deliver the Letter and Befriend Alphys

At Alphys’s Lab, interact with the front door while carrying Undyne’s Letter.

Slide the letter under the door.

This begins the Alphys friendship/date sequence.

Complete the event through to the Garbage Dump scene involving Alphys and Undyne. Your dialogue choices during the sequence do not cancel the route.

After the event ends and you leave the Garbage Dump, Papyrus will call and tell you to return to Alphys’s Lab.

That call signals that the True Lab is ready.

Step 10: Enter and Complete the True Lab

Return to Alphys’s Lab.

You will find a note from Alphys that directs you toward the door previously presented as her bathroom. The door actually leads to an elevator descending into the True Lab.

Once inside:

1. Explore the True Lab.
2. Encounter its unique enemies and story sequences.
3. Find all four colored keys.
4. Place each key into its corresponding slot.
5. Open the generator room.
6. Turn the generator back on.
7. Return toward the elevator.

After completing the True Lab, the story moves you back toward New Home.

At this stage, the route is effectively committed to the True Pacifist ending.

Step 11: Continue Through New Home and the Final Battle

Follow the newly available path through New Home.

The confrontation that follows is different from the regular Neutral ending and eventually leads to the battle with Asriel Dreemurr.

This fight is primarily story-driven. Continue surviving the attacks and use the special actions the game provides as the battle progresses.

You do not need to worry about accidentally killing Asriel during this sequence. Follow the available prompts until the story resolves.

Completing this encounter unlocks the full True Pacifist ending and credits.

Why Didn’t the True Pacifist Route Unlock?

If Undyne’s Letter or the True Lab sequence does not appear, check these conditions first:

• You gained EXP: any EXP from killing regular monsters or bosses invalidates the route unless you can reload a SAVE from before the kill.
• You skipped Papyrus’s hangout: return to his house in Snowdin if the event is still available.
• You did not give Undyne water: her friendship event will not unlock correctly without this action.
• You skipped Undyne’s hangout: visit her Waterfall home with Papyrus.
• You have not completed a Neutral ending yet: finish the game once, then reload.
• You have not progressed far enough: complete Mettaton EX and continue through the Neutral ending first.

A useful diagnostic is your character status. If you still have LV 1 and EXP 0, the run may often be recoverable by backtracking and completing a missed friendship event.

Can You Get True Pacifist on Your First Playthrough?

Yes. You can satisfy the pacifist requirements during your first playthrough, but Undertale must still register a Neutral ending before the final True Pacifist events become available.

The practical progression is:

Pacifist gameplay → Neutral ending → Reload SAVE → Undyne’s Letter → Alphys date → True Lab → True Pacifist ending.

You do not need to replay the entire game if your existing SAVE still has 0 EXP and the earlier friendship requirements were completed.

Sources & References

• The Undertale Wiki — True Pacifist Route: route requirements, friendship progression, Undyne’s Letter, Alphys event, and True Lab sequence.
• The Undertale Wiki — Endings: requirements separating Neutral, True Pacifist, and Genocide endings.
• The Undertale Wiki — Mettaton EX: ratings mechanics and peaceful battle requirements.
• The Undertale Wiki — True Lab: True Pacifist access requirements and progression through Alphys’s laboratory.
• The Undertale Wiki — Undyne’s House: requirements for befriending Undyne and the Hotland water event.
• Undertale by Toby Fox: in-game battle mechanics, SAVE progression, character events, and ending sequences.