Sans Undertale Guide

Sans Undertale Guide: Mr. Funny Bones

My fingertips tackle this Sans Undertale Guide with a bony glee. Though I’ve never worked on a farm, I love corny jokes. 

*sad drum-beating sound*

Okay, I won’t pummel you with my own puns as I tackle the joke-master of Undertale, Sans the Skeleton. From the moment you meet him, he is an RPG character like you have rarely encountered.

The game shows that he is clearly adamant in strength, speed, stealth, skill, and intellect. Yet, he isn’t there to fight you. He’s a lot like a conscious. Trying to warn you about the impact of your choices. 

While Sans may be your guide when he first meets you to some extent, there is no guide to him. No worries, I’ve got you covered. Bad puns and all. 

Undertale: Shape Your Destiny Beneath the Surface | GOG

Embark on an unforgettable journey through the underground world of Undertale, where every choice you make shapes the fate of monsters and humans alike. With its charming retro graphics and innovative gameplay mechanics, immerse yourself in a tale of friendship, determination, and the power of mercy.

Check Price Buy at GOG
We earn a commission if you make a purchase, at no additional cost to you.

Bottom Line Up Front: This Sans Undertale guide will cover the full extent of Sans in the first Undertale game. That includes pacifist and genocide routes and how Sans deals with you, the player, during them.

Key Details

  • Character Type: NPC/Boss
  • Difficulty: Hardest
  • First Encountered: Snowden Forest
  • Optional Fight: Yes
  • Personality: Caring, a great sense of humor, and quite lazy. 
  • Skills: Strength, Speed, Meta-Knowledge, and telekinesis.

Snowden Forest

Meeting Sans for the first time
Image by Bryan Hughes

You get hints of Sans before you encounter him. Toriel has a joke book, and it’s clear later on that she and Sans talk to each other at the entrance to The Ruins. Often sharing their comical quips with one another. 

Sans and Toriel had a very good relationship. You’ll find that most people are friends with the short, bone brother. 

You won’t see him immediately after you exit The Ruins into Snowden Forest. Instead, you’ll notice that you are being stalked by something. Something strong. Something fast, with glowing eyes in the shadows.

You’ll come up a bridge when a shadowy figure about the same height as you addresses you. 

“Don’t you know how to greet a pal?” 

You will, and you will also instantly learn two things. Sans is a full-on skeleton and a practical joker. 

A whoopee cushion will let out a long fart noise upon the shake. Sans will laugh, which will be par for how he is throughout the game, depending on your choices. 

The important part of this encounter is you learn Sans does not care about actually capturing anyone. He isn’t a threat.

In fact, he’s going to warn you about his brother Papyrus. A friendly fellow who you will also learn is neither bright nor dangerous. 

Most notably, Sans will address the camera with a wink. This is because, as hinted here, he is aware of the meta world in which he exists. You might say he is the good to Flowey’s bad. The light to his dark. 

This means San will know when you are starting a new run. This is even more of a hint that Sans is one of the strongest characters in the game. Luckily, it is very difficult to ever initiate a fight with him.

I’ll get into that later. For now, let’s look at how Sans affects the casual playthrough.

Sans Relationships

As you go through, you’ll see that Sans is pretty well-known throughout The Underground. Yet, there are a few relationships more important than others. 

His friend – Toriel

Toriel Undertale

As discussed earlier, Sans and Toriel have a good report. In fact, Sans is Toriel’s only remaining friend in Undertale when you arrive. It is difficult for most players to spare Toriel on their first try, and it will upset Sans to learn of her death. However, for the most part, this will only have an effect at the end of the game if you get the Neutral Ending.

His friend – Alphys

Alphys Undertale
Image from lgbtqia characters fandom

While their friendship doesn’t hugely impact the game, there is an odd connection to dogs. The dog food in Alphys’s lab is also in Sans’s room. There is also a trick you can do. Call Papyrus before entering The Lab where Alphys is. If you do, Sans will appear.

He will suggest there may be dogs in the lab. Another hint is that he knows nearly everything that is transpiring. In the True Lab, a lot of dogs were imprisoned. 

His Brother – Papyrus

Papyrus Undertale

If you kill Papyrus instead of finding a way to spare him, your relationship with Sans will be nearly irreparable. It will not put you in a fight with him by itself, but it will change how he treats you afterward. He will be specifically cold to you during your ending sequence, and you’ll get less interaction with him throughout the game. During his judgment of you, he will refer to you as, “You dirty brother killer.”

Hanging out with Sans

Hanging out with Sans
Image by Bryan Hughes

When you enter Waterfall, Sans will be guarding his sentry station. By guarding, I mean he will lazily be looking for an excuse to not be there.

If you did not kill Papyrus, Sans makes you an offer. 

Accept the offer, and you can hang out with Sans at Grillby’s. He’ll chat up a bit, and depending on what monsters you didn’t kill, Grillby’s will have plenty of patrons. In this fun little side-story, you learn Sans is well known.

You’ll get to choose what you eat. There is no large bearing on what occurs based on your choice. Sans will simply end up ordering the same food as you.

Sans will offer you ketchup when the food arrives, a burger, or fries, depending on your choice. If you accept the ketchup, aha! The bottle is rigged and will spill all over your meal. Harmless fun or a clear mistake, Sans doesn’t tell you. He swaps plates with you so you can eat, though. 

If you say no, he downs the whole bottle of ketchup himself. Makes me pretty sure he knew what would happen if you said yes, the practical joker he is. 

Then, things get interesting.

Sans tells you more about Papyrus and his relationship with Undyne. As this conversation goes on, Sans perhaps reveals some of his true power. 

“I wanted to ask you something,” Sans says. The whole room freezes as if time has stopped. The music changes from the theme Sans to Premonition. Sans starts talking about advice that Papyrus has been getting from a mysterious flower. Clearly referencing Flowey and showing actual worry.

He brushes it off as perhaps being an Echo Flower. Yet, it is certain that this is both Sans worrying about his brother, knowing of Flowey, and warning you. 

Time begins to flow again, and prankster Sans returns to his ways. 

He tries to stiff you with the impossible-to-pay 10000G tab he has and playfully blames you for keeping him from his duties. Whether you say yes or no, Sans lets you know he’s joking and tells Grillby to put it on his tab. 

If you did kill Papyrus, this scene never occurs. Patrons complain that Sans is never around anymore, and Sans’s music is not present when you visit Grillby’s. 

San’s Sightings

San's Sightings
Image by Bryan Hughes

Sans’s presence can be felt throughout the game. Here’s a list of places and the things that occur.

  • He plays a nice prank on you when you look through a telescope, leaving a red circle on your eye in Waterfall.
  • If Papyrus is not killed, he will sell concert tickets made of toilet paper in Waterfall.
  • If Papyrus is killed, a hooded figure will be watching you during Shyren’s battle in Waterfall instead. Clearly Sans.
  • Sans is slacking off at his post when you enter Hotland if you didn’t kill Undyne

*He is posted at many places, it seems, and barely guards any of them*

Sans Hot Land
Image by Bryan Hughes
  • Undyne will quit chasing you to yell at him before continuing the chase for an extra bit of comedy.
  • If Papyrus is alive, he also appears later in Hot Land selling Hot Dogs for 30G a pop. If you try to buy one with a full inventory, he piles 30 of them on your head for free. 
  • At the MTT Resort, you can grab another bite to eat with him. 
  • In this extra cutscene, you learn from his own words about his friendship with Toriel, though he doesn’t mention her by name.
  • He promised her he wouldn’t hurt any human that left The Ruins, hence why you’re alive. He jests. 
  • If you have died before and this is a reload, he will question whether or not he did a good job. Again revealing he is the only one who shares Flowey’s omniscience. 
  • The last sweet thing he says is, “Take care of yourself because someone really cares about you.”

The Last Corridor

Last Corridor with Sans
Image by Bryan Hughes

This is where your meeting will reveal the playthrough you’ve achieved if you were curious. It is in this corridor that Sans will pass judgment upon you. 

He opens up with this statement, “The end of your journey is at hand. In a few moments, you will meet the king. Together…You will determine the future of this world.”

He tells you that EXP and LV are actually acronyms in this game. Not for experience and love, no. 

EXP is short for Execution Points. For all the death you’ve caused. LoV is short for Level of Violence. To show how violent you truly are. It was a harrowing reveal for me. 

I can’t say I’ve ever played a game where I felt so bad for defending myself before. Upon learning this, I started a game over and went about killing nothing. It was much, much harder than killing. Crazy that. I’m not suggesting you do that. Sans would know anyways. Flowey certainly does. 

In any case, Sans will look at your EXP and LOV. 

If you have none, he will praise you(a pacifist run): Thankful for your compassion and kindness. He will let you know the world’s fate rests in your hands. You can give your Soul to Asgore and let the monsters break out, or take Asgore’s soul and break out yourself.

He believes you can do the right thing, and from me to you, good luck with that. 

If you have some EXP, but Papyrus is alive(positive, neutral run): Sans wants you to dwell on your choices. Ultimately, he says what happens next is in your hands. Showing that he believes you still can do right, even if you’ve strayed. 

If you have some EXP and Papyrus is dead(negative, neutral run): Meaning you didn’t kill everyone as in a True Genocide run but killed some, and Sans’s brother, he will not be kind. He believes you have a special power. He will ask if you think it is your responsibility to do the right thing. It won’t matter your answer because you killed his brother. He’ll leave you with that reminder. 

If you pass this scene and load a save to come back to it in this playthrough, he will judge you only on your LV. Talking to him afterward, he will tell you the session is over, and nothing will occur.

Hidden Room

So, how can you get into Sans’s room? The Last Corridor is the key. If you have heard Sans’s speech before, he will notice. He will point out that you appear bored and guess you are a time traveler. He’ll give you a code word. (You can achieve this on one playthrough by listening to him explain EXP and LoV, then reloading before he passes judgment).

You will need to have 0 EXP and 0 LV to unlock this.

Load your save up a few times to repeat the codeword and make him believe he is correct about your abilities. For some reason, he will give you the key to his room! Return to Sans and Papyrus’s house to unlock it and go inside. 

The room is a bit of an empty void. Fear not. Walk around a bit. Papyrus will turn on a light and reveal the room. Seems you were just using a treadmill in the dark, ha! Sans and his practical jokes. 

Sans room is a wonderful mess. Perhaps proof he is as lazy as he claims, a literal tornado of trash is in the corner of it. Search around the piles, specifically search the drawer under the lamp. You will acquire the Silver Key.

Another Hidden Room!

Sans’s Workshop is what the Silver Key opens. If you followed the above guide, you should have the Silver Key. Go to the back of Papyrus and Sans’s house to open the basement with the key.

There are mostly story things in here, no super impressive hidden items. You can see pictures of Sans with a bunch of people. If you come after the battle with Asriel, you can see a photo of you, Sans, and your friends. 

There is a badge in a drawer and schematics on the wall. The v1.001 patch made it so if you talk with Clam Girl and learn of the character Suzy, a cute note appears. Described as a poorly drawn picture of the three friends with the words “don’t forget” written on it. 

This room should be on your radar if you are a completionist (or a sentimentalist like myself). Otherwise, not getting it won’t have any big effect on the game or its endings. 

Genocide Route

This is where Sans seems to gain legendary status among Undertale fans. Unlike any other run or ending of the game, if you’ve been a murderous kill-happy player, Sans knows. 

In the Last Corridor, Sans does not judge you. He warns you. “You’re going to have a bad time.”

He will be your FINAL BOSS in a genocide run.

He challenges you to stop you from destroying all timelines of all worlds. He is recognized by many as the hardest fight in the entire game. While I don’t encourage a genocide run, I will help you through this fight.

Here is what you need to know.

Sans Stats

Sans Stats

  • HP: 1 (you can’t hit him with your first 22 attacks, so his HP is based mostly on your will to win and skill)
  • Damage: 1 (all his attacks do a guaranteed damage of 1 no matter your defense)
  • Special Effects: Hits Cause Karma Damage (you will lose 1 point of life for each point of KR as it drains to 0)
  • Defense: 1(again, it doesn’t matter as he dodges your first 22 attacks, guaranteed)

Defeating Sans will max out your LV(to 20). He drops no gold.

Be Prepared

You can better prepare for Sans by equipping the Torn Notebook and the Cloudy Glasses. It is the only way to get invulnerability frames and slow down the damage done by his Karma status. 

Suppose you have neither the Torn Notebook nor the Cloudy Glasses. In that case, you will have 0 Invulnerability and take damage every time you are hit. 

Sans can do up to 30 damage in an attack. Stacked with Karma damage, your work will be cut out for you. It’s common to die in seconds.

  • Items Suggested: Torn Notebook, Cloudy Glasses, Sea Tea. You can acquire all these from Gerson in Waterfall.
  • Extra Useful Items: Snowman Piece, you can take three pieces during a genocide route, destroying the Snowman. Save them for this fight. They restore 45HP upon use.

The Sea Tea heals 10HP, not much, but use it just once, and your speed will be increased for the whole battle. So, it is a great idea to use it in battle after taking your first damage. 

The Fight

I’ll start by listing the many attacks. Avoiding them will mostly be up to your nimble hands. It is rarely beaten on anyone’s first attempt. A damage-less run against Sans is impossible, as he will do about 36 guaranteed damage at the final stretch. Not getting hit is possible if you are a gaming master like this guy

Sans will begin by immediately slamming you, so be on guard at the very start. Don’t let his dialogue confuse you. You will need to jump, move around some bone pillars, then go middle, side, middle before the fight starts. Good luck.

Here are the attacks

Image by Bryan Hughes
  • Gravity Slam: Sans turns you blue and slams you against a side of the Battle Board. You need to jump out of danger as bones will rise up to strike you after being slammed.
  • Bone Barrage: Different Bone barrages will occur, similar to attacks you’ve endured. If you see platforms during an onslaught of bones, jump on them for safety. 
  • Gaster Blaster: Giant faces of bone will shoot massive lasers at you. There are three forms of this attack. Concentrated Blasts. Faces will surround the Bullet Board, and you will need to go in the middle or to the sides of the board to dodge the damage. Random. They will move around the board and blasts a big white laser from their mouths. Pay attention to their mouth’s direction so you can move out of the way. Last Blast. His final Gaster Blaster attack is speedy. Many skull faces merge to gather and 360 around the board. Move quickly with them in the small space left open by the blast to avoid damage. 
  • Board Assault: At a certain point in the match, bones will begin floating around your select screen and even in the attack box. They will damage you! Yes, he can hit you even during your turn! You need to dodge these bones when selecting fight, item, menu, or mercy.
  • Mercy: Don’t accept his mercy; you will be instantly killed. 
  • Boredom: His last attempt to win is to kill you with boredom. While it may take a while, once he says he has chosen to do nothing and not let you have a turn, you have to wait for him to fall asleep. When he does, use your soul to push the Bullet Board over the Fight menu and select fight. This will end Sans.

You must attack Sans 22 times to initiate the boredom. You don’t need to aim for the center of your attack board, so just click it as quickly as possible to avoid getting damaged by his board assault. 

After The Battle

Sans will be sliced nearly in half. He doesn’t simply disappear. Unlike other enemies, he starts to drip what appears to be blood from his mouth. He walks off to the side, “I’m going to Grillby’s.”

Once off-screen, you hear him ask his dead brother, Papyrus, what he wants to eat. It’s a sad ending, and I know many of us will get it for the sake of saying we did or seeing it. In my case, to write a comprehensive guide with firsthand experience.

Yet, I can’t help but feel this is one character I would’ve liked to have never slain. 

Multiple Ending Dialogue

Image by Bryan Hughes

True Pacifist Run. In this run, Sans will be bound like everyone else and appear as a lost soul during the fight. After you are successful, Sans will give you a phone call and update you on how everyone is. He and Toriel are back at exchanging jokes, and life is generally pretty good.

If you defeat Asriel but are otherwise good, a normal Pacifist run. Talking to Sans will have slightly different text depending on what you said to Toriel in calls at the beginning of the game. 

When Papyrus tries to introduce himself to humans in a good ending, Sans runs off to keep him out of trouble. 

During Neutral runs, it depends on who you killed and who you didn’t. Mainly not killing Papyrus will keep him somewhat friendly toward you. Sans is still your buddy if you keep his friends and close relationships alive.

In the credits, you can see him riding a tricycle on a highway. Typical ridiculous stuff. His brother driving beside him in a car, gets irritated when Sans passes him on the tricycle. Which is fair enough. 


Question: Is Sans the hardest boss?

Answer: Yes. It is an opinion, of course, but yes.

Question: Are Sans and Alphys in a relationship?

Answer: No. They are merely friends. Alphys is interested in Undyne. 

Question: Does Sans have the same powers as Flowey?

Answer: He does have some of the powers. For instance, he knows when you have reset the game, and he has knowledge about the true secrets of The Underground.

That’s Our Sans Guide

Hey! Thanks for reading this comprehensive guide to the wonderful character from Undertale, known as Sans. 

Did you know Sans can be spotted in Super Smash Bros as a skin for one of your Mii characters on the Switch? That content does need to be downloaded for 0.75 USD. 

For now, good luck and good gaming!

Undertale: Shape Your Destiny Beneath the Surface | GOG

Embark on an unforgettable journey through the underground world of Undertale, where every choice you make shapes the fate of monsters and humans alike. With its charming retro graphics and innovative gameplay mechanics, immerse yourself in a tale of friendship, determination, and the power of mercy.

Check Price Buy at GOG
We earn a commission if you make a purchase, at no additional cost to you.
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