How to Fix Grainy Renders in Blender?

You’ve spent hours creating the most amazing modeling and shading, then pressed F12 to see the final render. But unfortunately, the result is not as clean as you want; it is noisy and grainy. In fact, noise is a common phenomenon, especially in Cycles. It usually occurs when Blender does not have enough data to calculate the lighting accurately. So, how do we remove grainy renders in Blender? That is the purpose of this article, where we will learn why your render is grainy and how to fix it effectively without overloading your system.

Cycles uses path tracing with next event estimation, which isn’t great for rendering all kinds of lighting effects, like caustics. But it’s good for rendering larger, more detailed scenes than some other rendering algorithms. That means Cycles simulates light from sources and predicts how it will bounce off objects and materials in the environment through path tracing. Of course, not all light sources are the same, so Cycles can’t always predict their paths accurately, which can lead to noise and graininess. 

You may need more light paths in your scene, for example, by using specific materials like glass. The materials and lights you choose for your scene can also greatly impact the final render. You should pay more attention to your lighting setup and material complexity when rendering in Blender. Also, light portals are important, especially for interior scenes. Indoor light coming in through windows or small openings makes it difficult for Cycles to direct light rays when sampling. Then, Light Portals help Blender understand where the main light source is for more efficient sampling.

Source: Deepal Graphics

The next reason makes your image might appear grainy could be a low sample count or a high noise threshold. Another thing you might think of is that your computer is lower-end. This makes it difficult to render complex images with many details and polygons, resulting in long render times and noisy rendering. You can refer to the article Blender Cycles Optimization Tips for Low-end PC (2025) for some useful tips! 

So, when using Cycles, there may be times when the render doesn’t look the way you expect. Sometimes, you will see a grainy mess with tons of noise on your render, instead of a nice-looking image. Let’s see what we can do to remove grainy renders in Blender! 

As mentioned above, Cycle focuses on path tracing to create and calculate the lighting of the scene. To get the most accurate results, Blender needs to perform the calculations as many times as possible to accurately map all the objects in the scene. This process is called sampling, meaning that the more samples Blender uses, the more accurate the results will be.

Of course, the number of samples needed for a scene depends on the scene’s structure. The more complex the scene, the higher the number of samples needed, for example, a forest scene or a city with many buildings. Therefore, a low sample count means more grain, noise, and ‘fireflies’ (white pixels that occasionally appear in the scene). In this case, we need to estimate the minimum sample count and try increasing the sample count until we get the desired result.

Sample settings for render (Source: blenderbasecamp.com) 

You can increase the sample count in Render Properties > Sampling. Note that higher sample counts will increase the render time. This is the simplest solution, and in 99% of the cases, it works; if not, then refer to the solutions below.

Another option to improve rendering in Blender Cycles is to lower the noise threshold. This imposes a per-pixel limit on the number of samples that can be used to remove noise. It also acts as an efficiency estimator, preventing Blender from using too many samples in areas of the image that are already at their best. The lower the noise threshold, the longer it takes to remove noisy pixels in the image, and the higher the value, the faster the sample will move to subsequent sections.

You can also use Denoise to remove grainy renders in Blender. With the denoising function, Blender can clean up your image after calculating the samples. The biggest advantage of denoising images is that it can clean up images even when they have a low sample count. So, if used properly, the denoiser can still significantly reduce the render time while still maintaining a clean result.

However, this function also has a drawback, which is more obvious when using a low sample count. The denoiser takes the image it receives after the samples are calculated, then it uses whatever data is there to clean up the image. This means that too few samples will significantly limit the quality of the details that can be seen in the image. Therefore, we should still use a moderate sample count and a suitable noise threshold for the denoiser to work properly without losing details.

To enable the Denoiser, go to the Render Properties panel > Render > Denoise. Image denoising is enabled by default with your 3D viewpoint. But it is disabled for rendering, so we need to tick it on. Then, click the arrow next to the checkbox, and it will open a small menu with a few settings for denoising.

The Noise option is the most important. The noise options can vary depending on your hardware. Sometimes, one method can give cleaner results or preserve finer detail. The Passes option will determine what kind of information the denoiser calculates. By default, it is set to Albedo and Normal, so we should leave it that way. Finally, if you have the image denoiser open, you will have an additional Prefilter option. If you have albedo and normal passes enabled, you can choose how the prefilter works to prioritize speed (faster denoising) or accuracy (cleaner denoising, better detail retention).

While the denoising setting will take some time, it is not a significant amount of time in terms of overall render time. You should adjust this setting carefully and appropriately.

Consider fireflies, those isolated white spots that appear when rendering glossy or transparent materials. We often see this phenomenon in interior scenes, when the light source is shining in from outside through a gap like a window. The firefly effect is harder to remove than regular noise or pixels because it comes from the calculation of real light. Sometimes, increasing the number of samples to a very high level still doesn’t get rid of these spots. Using denoise can sometimes help, but it can also cause problems such as distortion or loss of detail. So we need to address the root of the problem.

Source: digitalarthub.net 

First, try increasing the number of light paths in the scene. This will increase the accuracy of the path tracing, thereby reducing the appearance of fireflies to some extent. Next, you can use portals. Portals will change the way light enters the scene and significantly reduce the number of fireflies generated.

Next up is Multiple Importance Sampling, a feature that is enabled by default in Blender. This helps calculate light paths more efficiently, which reduces noise and fireflies in the render. But it doesn’t completely clean up noise or grain. Since Multiple Importance Sampling works by treating lights and objects differently depending on the context, one object might have no fireflies, but another object in the same scene might still have them. Of course, this technique analyzes each element of the scene more deeply, so it will render more slowly. Still, if the above methods don’t work, this is something to try.

Before and After using Multiple Importance Sampling (Source: blender.org)

We come to the final option, using Eevee as an alternative to Cycles. You might consider Eevee because it computes the scene using a different method than Cycles, which is rasterization. While Cycles uses path tracing to calculate the effect of each ray of light as it bounces off the surface of an object, Eevee estimates how light interacts with surfaces and materials.

Since Cycles’ method is more intensive, it can introduce noise or pixelation in the render, but Eevee doesn’t. You won’t have to worry about noise in your renders with Eevee. However, Eevee also comes with the disadvantage of not being very realistic. So if you want to create realistic images, this disadvantage is hard to ignore.

Grainy renders in Blender are annoying, but they can be fixed. With some fine-tuning of the sample count or denoise settings, you can clean things up pretty well. The key is knowing where the noise is coming from and choosing the fix that works for your scene. If you’re having trouble with noisy, grainy, or blurry renders in Blender, give these a try!

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References: blenderbasecamp.com, digitalarthub.net