Auto Tile Size

Believe it or not, the render tile size can make a huge difference to your render times, but it's not easy to know what the best size for your scene is. There are so many factors to take into account, but lucky for you, this add-on takes care of everything.

In fact, all you need to do is enable this add-on (it's included in Blender by default), and you can forget about tile sizes altogether!

Everything is handled for you in the background, including separate tile sizes for CPU and GPU rendering for Cycles, as well as Blender Render. By default, around 32x32 is used for CPU, 256x256 for GPU, and 64x64 for Blender Render - but you can change it with the click of a button!

How it works

The first thing you'll notice is that the tile size is not usually exactly what you tell it to be. For example, if the target is set to 256 (as is default for GPU rendering), the tile size might actually by 240x216.

Why? Well that's the whole point of this add-on actually! It calculates what the optimal tile size is based on two things:

  1. What is used to render
  2. The size of the rendered image

1. Render Engine and Device

You probably already know that CPU and GPU rendering are quicker with different tile sizes, but did you know how much of a difference it makes? As I was writing this add-on, I did extensive testing with a number of very different scenes with different resolutions. Here are the results:

Tile Size Average render time (seconds)
X Y Cycles CPU Cycles GPU Blender Render
16 16

138.64

836.38

111.98

16 15

138.11

850.02

112.20

32 32

138.95

247.03

90.16

32 30

138.42

280.22

90.60

50 50

138.76

156.19

87.24

64 64

140.51

110.07

86.07

64 90

139.76

112.07

86.47

90 90

140.61

86.51

86.46

100 100

143.29

84.08

85.54

128 128

144.36

81.98

85.95

128 135

143.74

83.71

86.82

200 200

155.84

76.29

84.81

256 256

180.38

74.16

85.43

240 270

178.64

71.78

90.37

512 512

339.70

114.14

128.17

480 540

350.41

236.06

129.49

2. Render Resolution

Let's say we want a render a 1920x1080 image using our GPU - we know the a tile size of 256x256 is good for GPU rendering, but take a look at a 1080p image divided into 256x256 blocks:

Notice the long an narrow tiles along the top and right edges of the image. This happens when your tile size is not a perfect factor of the resolution, and often causes your render to take a bit longer because those tiles on the edges are much smaller than the rest. As you can see in the table above, small tiles generally mean a slower render (even with CPU if the tiles are less than 16 pixels wide/high)

To fix this, the add-on figures out what tile size you need in order to make every tile the same size:

In this case, 240x216 will make 8 by 5 equally sized tiles.

It also takes the render border region and resolution percentage into account, using them in the calculations and updating the tile size whenever one of those changes.