If you're tired of that default green bar at the top of the screen, learning how to write a roblox health bar gui script is one of the best ways to make your game actually look professional. It's one of those small changes that makes a massive difference in how players feel when they're running around your world. The default UI is fine for testing, but if you want your game to have its own identity, you've got to build your own.
Honestly, it isn't nearly as intimidating as it sounds. Even if you're just starting out with Luau, creating a bar that shrinks and grows as a player takes damage is a great "Level 1" project. It covers the basics of UI design, variables, and events. Plus, it's really satisfying to see that bar slide smoothly instead of just snapping from full to empty.
Setting Up the Visuals First
Before we even touch a line of code, we need something for the script to actually control. You can't have a roblox health bar gui script without a bar, right? Head over to the StarterGui in your Explorer window and add a ScreenGui. Let's name it "HealthGui" just to keep things organized.
Inside that ScreenGui, you'll want to add a Frame. This will be the "background" or the border of your health bar. Give it a dark color, maybe a stroke (outline), and size it however you want it to appear on the screen. Now, here's the important part: add another Frame inside that first one. This second Frame is the actual health bar—the part that's going to move.
A little pro-tip: make sure the inner Frame's size is set using Scale rather than Offset. If you use Offset (pixels), your health bar might look perfect on your monitor but end up being microscopic on a phone or huge on a 4K screen. Set the inner bar's size to {1, 0, 1, 0} so it fills the entire background frame to start with. Change its color to a bright green, and we're ready to move on.
Writing the Basic Health Bar Script
Now we get to the fun part. To make this work, we're going to use a LocalScript. Since the UI only exists on the player's screen, a LocalScript is the right tool for the job. You'll want to place this script directly inside the inner green Frame we just made.
The logic behind a roblox health bar gui script is actually pretty straightforward. We need to tell the script to look at the player's character, find the Humanoid, and then watch that Humanoid's health. Every time the health changes, we want the bar to resize.
Here's a simple way to think about the math: we divide the CurrentHealth by the MaxHealth. If you have 50 health out of 100, that's 0.5. We then take that 0.5 and apply it to the X-scale of our Frame. It's basically just basic fractions from middle school coming back to haunt you, but in a cool way.
Making it Smooth with Tweening
If you just set the size directly, the bar will "snap" to the new health value. It works, but it looks a bit "old-school" and janky. To make it look modern, we use something called TweenService. Tweening is just a fancy word for animating a property from one value to another over time.
Instead of the bar instantly jumping from 100% to 50%, a tween will make it slide smoothly over, say, 0.3 seconds. It makes the game feel much more polished. In your script, you'll define the TweenInfo—which tells Roblox how long the animation should take and what "style" of movement to use (like linear or bouncy)—and then play that tween whenever the health changes.
Players notice these little things. When they take a hit and see that bar rapidly sliding down, it adds a sense of impact that a static bar just can't match.
Adding Text to the Bar
While a sliding bar is great, sometimes players want to know exactly how much HP they have left. Is it 5 or 10? That makes a big difference when you're deciding whether to run away or keep fighting. Adding a TextLabel on top of your frames is the easiest fix.
Inside your background Frame, add a TextLabel and set its background transparency to 1 so only the text shows. You can then update your roblox health bar gui script to change the text whenever the health changes. You can make it say something like "100/100" or just "100%".
Just remember to set the ZIndex of the TextLabel higher than the health bar frames, otherwise, the green bar might cover up your numbers, which is definitely not what we want.
Handling the Player Spawning
One thing that trips up a lot of beginners is what happens when a player dies and respawns. By default, things in the StarterGui are wiped and re-cloned when the character resets. If your script is trying to reference a "Humanoid" that doesn't exist anymore because the player died, the script will break.
To handle this, your script needs to wait for the new character to load in. You can use the CharacterAdded event to make sure your script always has a fresh handle on the new Humanoid. It sounds like extra work, but it's the difference between a health bar that works once and a health bar that works for the whole session.
Changing Colors Dynamically
If you want to go the extra mile, you can make the bar change color based on how low the health is. Most games use the classic Green -> Yellow -> Red system. You can do this with a few if statements in your script.
For example, if health is above 70%, keep it green. If it's between 30% and 70%, turn it orange or yellow. If it's below 30%, make it bright red. It's a great visual cue that tells the player, "Hey, you're about to lose, do something!" It's surprisingly easy to implement once you have the basic math of the health percentage figured out.
Testing and Troubleshooting
Once you've got your roblox health bar gui script written and your UI laid out, it's time to hop into Play mode. The easiest way to test it is to go into the "Server" view while playing, find your character in the Workspace, and manually change your Humanoid's health.
If the bar doesn't move, check the Output window. Usually, it's a small typo or a pathing issue (like the script looking for "Frame" when you named it "HealthBar"). Don't get discouraged if it doesn't work on the first try; debugging is literally 90% of game development.
Another common issue is the bar shrinking from the center instead of from the side. This usually happens because of the AnchorPoint. If you want the bar to stay glued to the left side and shrink towards the left, make sure your AnchorPoint is set to (0, 0.5) or (0, 0) and that your position is adjusted accordingly.
Final Touches for Polish
Once the logic is solid, spend some time on the aesthetics. You can add a slight gradient to the bar to give it some depth, or maybe a "pulse" effect when health gets really low. Some developers even add a "ghost bar"—a white or red bar behind the main one that drains slowly after the main bar has already moved. It's a common effect in fighting games and looks incredibly professional.
The beauty of creating your own roblox health bar gui script is that it's yours. You aren't stuck with the boring defaults. You can make it a circle, a vertical bar, or even a heart that empties. The scripting logic remains almost identical; only the visuals change.
Roblox gives you a ton of freedom with GUIs, and once you master this, you can move on to mana bars, experience bars, or even boss health bars that appear at the top of the screen. It's all just variations of the same concept: taking a number from the game and turning it into something a player can see and understand at a glance. Keep experimenting, keep breaking things, and you'll have a great-looking game in no time.