How Decals Work in Roblox
A decal is an image texture you apply to a surface in your game. It works differently from a regular material. When you upload an image as a decal, Roblox treats it as a separate layer that sits on top of whatever material is already there. You control where it shows, how big it is, and whether it repeats. The process itself is straightforward once you understand the file requirements and the Studio workflow. Start by making your image. Keep the dimensions at 512x512 pixels or 1024x1024. Anything outside those standard sizes either gets compressed awkwardly or wastes memory. Use PNG with transparency if you need edges that blend into the base material. JPG introduces compression artifacts that become obvious on large walls in-engine. Once the image is ready, go to the Roblox website and navigate to the Creator Dashboard, then select Assets and click Upload. Choose your file and label it clearly. Roblox charges 10 Robux to upload a decal asset. After it processes, grab the asset ID from the URL.
In Roblox Studio, select the part you want the decal on. Go to the Properties window and find the Decal property under Surface. Paste the asset ID there, or use the decal browser to pick it visually. Resize by adjusting the Size property of the decal object. Position it with the Position and Rotation settings. That is the basic flow. There is a faster path if you are working with multiple parts. Insert a Decal object directly from the Explorer panel instead of using the Surface property. This gives you more control over clipping, transparency blending, and anchor point placement. It also makes it easier to script dynamic decal changes later. I ran into a specific issue recently where a decal I uploaded looked completely different after placing it on a slanted surface. The texture was skewed and stretched in ways the preview never showed. The problem came from the part's CFrame rotation interacting with how Roblox maps UV coordinates on non-axis-aligned surfaces. My workaround was to create a dedicated flat brick just for the decal, position it slightly in front of the slanted surface using a small offset, and parent it under the same model. It adds an extra part to your hierarchy but it fixes the distortion completely and the visual result is indistinguishable from a properly mapped decal.
One thing beginners consistently get wrong is the difference between a Decal and a TextureMap. A TextureMap applies to the entire face and stretches to fill it. A Decal is an independent object with its own boundaries. If you need a logo that stays the same size regardless of the part it is attached to, use a Decal. If you need a repeating pattern like bricks or tiles across a whole wall, a Material with a texture map is usually the better choice. Another detail that causes problems is the transparency handling. Decals do not automatically respect the transparency of the underlying part. If you make a wall semi-transparent, the decal remains fully opaque unless you adjust it separately. You have to set the decal's Transparency property individually, or script it to match the parent material in real time. There are also performance considerations worth noting. Each decal is a draw call. A room with twenty decals on every wall will hit the renderer harder than you might expect, especially on lower-end devices. If you are building large interiors, consider combining repetitive decals into a single texture atlas and applying that to the whole surface instead. It reduces draw calls significantly and the visual quality is often better because there are no seam lines between individual decal placements.
Get the Full Details
Scripting decal changes at runtime is common for things like scoreboards, dynamic signage, or player-controlled customization. You can change a decal's Image property directly through Lua, which means you can swap images without re-uploading assets. The tradeoff is that remote events and client-server data flow become necessary if multiple players need to see the same change simultaneously. That adds complexity, so only go down that path if your game actually requires live updates. The upload queue on Roblox is another minor frustration. During peak hours, processing can take several minutes. If you are iterating quickly on image designs, you will notice the delay. The workaround I use is to keep a small library of already-uploaded placeholder decals and swap them in first, then replace them with the final versions once everything is functionally working. It saves a lot of waiting around. If you need bulk uploads for a project with dozens or hundreds of decals, the manual dashboard approach becomes tedious. There is no official bulk upload tool from Roblox. Some developers write custom scripts using the Roblox API to automate the process, but that requires additional setup and careful rate-limiting to avoid getting throttled. For smaller teams just starting out, sticking with the manual upload is usually fine. Once you cross the fifty-decal mark, it is worth evaluating whether automation makes sense for your pipeline.
File size matters more than most people realize. Roblox compresses uploaded images aggressively. A 10MB PNG will be shrunk down considerably, which can introduce blurriness on high-resolution screens. Keeping your source files under 2MB before upload results in a noticeably cleaner final product in-game. Crop out unnecessary transparent space around your design before uploading. That alone cuts file size without affecting the visible portion of the decal.
Quick Reference for Common Decal Settings
Image property: accepts the asset ID or a direct URL to an image. Changing this at runtime swaps the displayed texture. Transparency: controls how see-through the decal itself is. Does not inherit from the parent part. Size: determines the physical dimensions on the surface. Set manually or scale proportionally.
Rotation: rotates the decal around its center point in 2D space relative to the face. Face: only relevant when inserting a Decal object directly. Determines which side of the part the decal attaches to by default.
