Getting a roblox explosion blast radius script to work properly is usually the difference between a game that feels polished and one that feels like a broken tech demo. Most people start out by just spawning a default Explosion object, which is fine for a start, but if you've ever tried to make a tactical shooter or a destruction-based simulator, you know those default settings can be a bit of a headache. They tend to blow things up through walls or launch parts into the stratosphere without much control.
The thing about Roblox explosions is that they're actually pretty versatile if you know which properties to poke. When you create an explosion via script, you aren't just making a visual bang; you're creating a sphere of influence that calculates physics and damage. If you don't dial in that blast radius correctly, your players are going to get frustrated when they die from a grenade that went off in a completely different room.
The basics of spawning the explosion
Let's look at the simplest way to get this running. You're likely working within a Tool script or a ServerScript inside a part. To get a basic roblox explosion blast radius script moving, you need to instance the explosion and then tell it where to go.
lua local function createExplosion(position) local explosion = Instance.new("Explosion") explosion.Position = position explosion.BlastRadius = 15 -- This is the magic number explosion.Parent = game.Workspace end
In this little snippet, the BlastRadius is the property that defines how far the "shockwave" travels. It's measured in studs. If you set it to 15, everything within a 15-stud radius of that center point is going to feel the heat. But here's the kicker: by default, the Explosion object doesn't actually "kill" players unless it touches their character's parts, and even then, it depends on the BlastPressure.
Why Blast Pressure matters as much as Radius
A lot of developers overlook BlastPressure. While the radius tells the script how far the explosion reaches, the pressure determines how much "oomph" it has. If you have a huge radius but zero pressure, things will get hit by the explosion but nothing will move. It'll just be a weird, ghostly flicker.
On the flip side, if you crank the pressure up to something like 1,000,000, you're going to send unanchored parts flying across the entire map. For a standard "frag grenade" feel, I usually find that a pressure between 50,000 and 500,000 works best. It gives that satisfying kick without breaking the physics engine.
Controlling who gets hurt
One of the most common questions is how to make an explosion that only hurts enemies or only destroys certain parts. The default Explosion object has a Hit signal. This is super useful because it fires for every single part caught in that blast radius.
Instead of relying on the default Roblox behavior (which automatically breaks joints like necks and shoulders), you can set DestroyJointRadiusPercent to 0. This effectively makes the explosion "harmless" in terms of the engine's built-in killing mechanic, allowing you to handle the damage yourself through code.
```lua explosion.DestroyJointRadiusPercent = 0
explosion.Hit:Connect(function(part, distance) local character = part.Parent local humanoid = character:FindFirstChildOfClass("Humanoid")
if humanoid then -- Calculate damage based on how far they are local damage = 100 * (1 - (distance / explosion.BlastRadius)) humanoid:TakeDamage(damage) end end) ```
By doing this, you're making the roblox explosion blast radius script much more dynamic. A player standing right on top of the bomb takes 100 damage, while someone on the very edge of the radius might only take 5 or 10. It feels a lot more natural than just a "you're in or you're out" death zone.
Dealing with walls and obstacles
This is where the standard Roblox explosion often fails. By default, the blast radius is a perfect sphere that ignores walls. If you're in a house and a bomb goes off outside, you're probably going to die anyway. To fix this, you have to get a little fancier with something called Raycasting.
Basically, when the explosion hits a player, you want to draw an invisible line from the center of the explosion to that player. If that line hits a brick wall before it hits the player, you know they're shielded.
It sounds complicated, but it's really just a few extra lines in that Hit function. It keeps the game fair. No one likes getting killed by a grenade through a foot of solid concrete. If you're building a competitive game, this isn't just a "nice to have" feature; it's pretty much mandatory.
Making it look good (Visuals vs. Physics)
Sometimes you want a massive visual explosion but a tiny physical blast radius. Or maybe you want a huge shockwave that knocks people over but doesn't actually show a giant fireball. The trick here is to separate your visual effects from the roblox explosion blast radius script.
You can use ParticleEmitters for the smoke and fire. When the script triggers, you spawn the particles and the Explosion object at the same time. You can set the Explosion's Visible property to false if you don't like the default purple/orange sphere Roblox provides. This gives you total creative control. You could make a "gravity bomb" that pulls parts in by using negative BlastPressure, even though the visual effect looks like a swirling black hole.
Performance considerations for big maps
If you're planning on having hundreds of explosions going off—maybe a carpet-bombing killstreak or a chaotic destruction game—you need to be careful. Every time an explosion fires, the engine has to check every single part within that radius. If your blast radius is 500 studs and there are 10,000 parts in your city, your server is going to have a bad time.
To keep things smooth, try to keep your blast radii as small as you can get away with. If you need a "nuke," don't just make one massive explosion. It's often better to script a sequence of smaller explosions or use a different method entirely, like GetPartBoundsInRadius, which is often faster for just finding characters without calculating the physics pressure on every tiny piece of debris.
Common hiccups to avoid
I've seen a lot of people struggle with explosions because they forget that BlastRadius only affects unanchored parts. If your entire map is anchored (which it should be for performance), the explosion won't seem to do anything to the environment. You have to manually "unanchor" parts in the Hit function if you want them to fly away when the bomb goes off.
Another thing is the "Double Hit." Since characters have multiple parts (Head, Torso, Arms), the Hit event will fire for each of those parts. If you don't have a check in place to see if you've already damaged that specific player, your script might end up hitting them six times in one millisecond, instantly killing them even if they were on the edge of the blast. Using a simple table to keep track of who you've already processed is an easy fix for this.
Final thoughts on the blast radius
At the end of the day, a roblox explosion blast radius script is a tool. Whether it's a tiny pop from a firecracker or a map-leveling event, the logic remains the same. It's all about balancing that radius, the pressure, and how you handle the damage detection. Once you move away from the default settings and start coding your own logic into the Hit event, you'll find you can create some really cool, unique gameplay mechanics that make your game stand out. Just remember to test it with a few friends—nothing reveals a broken blast radius faster than a bunch of players trying to hide behind thin wooden crates.