Lighting & rendering · Intermediate

Fireflies

Bright speckled pixels that scatter across a path-traced render

What are fireflies in rendering?

Fireflies are bright, isolated white or colored pixels that speckle a ray-traced or path-traced render. They appear when a few random light paths happen to reach a very bright, hard-to-find light, such as a small lamp seen through glass, and there are too few samples to average them out.

Think of it like this

It is like a crowd photo where a few phones flashed at once: most of the image is fine, but scattered dots blaze white.

Where it fits in a 3D project

  1. Create
  2. Surface
  3. Rig
  4. Animate
  5. Render
  6. Export

Render: Lighting the scene and turning it into images or video.

How fireflies work

  1. 01The renderer averages many random light paths for each pixel.
  2. 02A rare path lands on an intense source, like a tiny lamp or a caustic.
  3. 03That one bright sample outweighs the rest, so the pixel glows.
  4. 04With few samples, those spikes stay visible as scattered dots.

Fireflies vs noise

PropertyFirefliesNoise
Looks likeScattered bright dotsEven grain everywhere
CauseRare, very bright light pathsToo few samples overall
FixClamping, larger lights, fewer causticsMore samples or denoising
DenoiserCan smear them into blotchesRemoves it well

General noise fades with more samples; fireflies often need their cause fixed, because even many samples can leave a few behind.

Where fireflies are used

  • Interiors lit mostly by bounced light
  • Glass, water and jewelry renders with caustics
  • Low-sample previews and quick test renders

Beginner tip

Find the source first. Fireflies near glass or shiny metal usually come from caustics or sharp reflections of small lights; making that light larger or turning caustics off often cures them.

Terms related to fireflies

Fireflies FAQ

How do I get rid of fireflies?
Raise samples, clamp indirect light to cap extreme values, make small lights larger, and turn off caustics you do not need. A denoiser cleans what is left, though it can smear bad fireflies.
Why do fireflies appear in renders?
A few random light paths happen to hit something very bright and hard to find, such as a small light seen through glass. Those rare, extreme samples are too strong for the pixel average to hide.
How do I reduce fireflies in Blender?
In the path-tracing engine’s Light Paths settings, set indirect Clamping to a modest value, enable Filter Glossy, and turn off caustics if the scene does not need them. Then raise samples or turn on denoising.
Does clamping make renders less realistic?
Slightly. Clamping caps how bright any one sample can be, so it trims some real highlights along with the fireflies. Clamp indirect light only, and use the highest value that still removes the speckles.

Updated October 29, 2026 · Browse all 3D terms