If you've been looking for a roblox automatic size script to make your characters grow or shrink based on gameplay, you're in the right place. It's one of those features that seems really complicated from the outside, but once you break it down, it's actually pretty straightforward. Whether you're building a "big man" simulator or just want players to shrink when they hit a certain obstacle, getting the scaling right is key to making your game feel polished and fun.
I remember when I first started messing around with character scales in Studio. I thought I had to manually adjust every single limb's mesh property. It was a nightmare. I'd end up with a character that had giant legs and a tiny head, looking like some kind of weird glitch. Thankfully, Roblox has made things a lot easier over the years with built-in scaling values.
Why bother with automatic scaling?
Let's be real—growth simulators are everywhere on Roblox. There's something weirdly satisfying about clicking a button, getting a bit of "strength," and watching your avatar slowly tower over everyone else on the map. But it's not just for simulators. You could use a roblox automatic size script for power-ups, boss fights, or even just as a cosmetic reward for players who reach a certain level.
The "automatic" part is what matters. You don't want to be manually updating a player's size every time they gain a point. You want a script that listens for a change in a value (like "Strength" or "Size") and just handles the heavy lifting for you. It saves you time, and it makes the game run a lot smoother for the players.
How the scaling actually works under the hood
Before you just copy-paste some code, it helps to know what's happening. Inside every R15 character model, there's a bunch of "Value" objects sitting inside the Humanoid. These are things like BodyHeightScale, BodyWidthScale, BodyDepthScale, and HeadScale.
If you change the number in BodyHeightScale from 1 to 2, the character doubles in height. Simple, right? The "automatic" part of our script is basically just a middleman. It waits for a stat to change and then pushes that new number into those scale values.
The basic logic of the script
The most common way to set this up is by using a NumberValue stored in the player's leaderstats. Let's say you have a value called "Size." You'll want a script in ServerScriptService that watches that value.
Whenever that "Size" value changes, the script triggers a function. This function finds the player's character, looks for the Humanoid, and then updates those four scale values I mentioned earlier. If you do it right, the player grows in real-time right before your eyes. No respawning necessary, which is a huge plus for user experience.
Making it feel smooth
One mistake I see a lot of new developers make is only scaling the height. If you only increase BodyHeightScale, your player ends up looking like a stretched-out piece of taffy. It's not a great look.
To keep things proportional, you generally want to scale the height, width, and depth all at the same time. Some people even like to scale the Proportions and BodyTypeScale values too, but that can get a bit wonky depending on what kind of avatars your players are wearing. I usually stick to the main three (Height, Width, Depth) and maybe the HeadScale if the tiny-head-big-body look isn't what I'm going for.
Handling the "Too Big" problem
Here's something to keep in mind: if you let players get too big, things start to break. You might find your players clipping through the ceiling or getting stuck in doorways. Or, even worse, their physics start acting up, and they launch themselves into the stratosphere just by walking into a wall.
When you're writing your roblox automatic size script, it's a smart move to put a "cap" or a limit on how big they can get. You can just use a simple if statement to check if the new scale is above a certain number. If it is, just set it to the maximum allowed size. Your map's geometry will thank you.
Adding some flair with animations
When a character gets massive, they shouldn't really move at the same speed as a tiny character. It looks a bit silly to see a giant sprinting around with the high-pitched footsteps of a normal-sized avatar.
You can actually link the WalkSpeed and JumpPower to the size value as well. As the player gets bigger, maybe they get a bit slower but jump higher (or lower, depending on your game's logic). This makes the size change feel "heavy" and impactful. It's those little details that separate a basic game from one that people actually want to keep playing.
What about R6 characters?
I know there are still plenty of R6 purists out there. If your game uses R6, a roblox automatic size script is a bit of a different beast. R6 characters don't have those handy scale values built into the Humanoid. To scale an R6 character, you usually have to manually adjust the Size property of every limb and then reposition the joints (Motor6Ds).
Honestly? It's a headache. If you're planning on a game centered around size changing, R15 is definitely the way to go. It handles all the limb positioning and joint offsets for you automatically. If you absolutely must use R6, you'll probably want to look into a specialized scaling module from the Developer Forum, because coding that from scratch is a bit of a rabbit hole.
Common pitfalls to avoid
I've broken plenty of games trying to get this right. One thing that always trips people up is the CharacterAppearanceLoaded event. If you try to change a player's size the literal millisecond they join, the script might run before the character has even finished loading. The result? Nothing happens, or the game throws an error because it can't find the Humanoid yet.
Always make sure you're waiting for the character to actually exist in the workspace. Using player.CharacterAdded:Wait() is a lifesaver here. It ensures the body parts are actually there before you start trying to stretch them out.
Another thing is server-side vs. client-side. You definitely want your roblox automatic size script to be a server script. If you do it on the client (in a LocalScript), the player will see themselves as huge, but to everyone else in the server, they'll still be normal size. That leads to all sorts of "ghost" collisions and weirdness. Keep the scaling on the server so everyone sees the same thing.
Final touches and testing
Once you've got the logic down, spend some time testing it with different avatar types. Roblox players wear some pretty wild stuff—huge wings, tiny packages, layered clothing. You want to make sure your script doesn't turn a player wearing a "Mech" suit into a terrifying pile of floating parts.
If you notice things looking weird, you might need to adjust how the HeadScale interacts with certain hats. But for 90% of cases, the standard scaling values do a surprisingly good job of keeping everything together.
Anyway, that's the gist of it. Setting up a roblox automatic size script isn't just about changing a few numbers; it's about making sure that change feels natural within the world you're building. Play around with the values, don't be afraid to break things, and you'll have it working in no time. It's a super rewarding feeling when you finally see that "Level Up" pop-up and your character grows right on cue!