[U] How to calculate Cycles Render Times

Update: le717 has released an update to the calculator. He improved the code a bit, and added a render engine-neutral animation calculation. I’ve already updated the download link. -rioforce

Here’s a quick tutorial on how to calculate render times for Cycles.
Instead of giving you lots of math, I’ll just let you check out this cool program le717 and I put together. ๐Ÿ™‚

Render Time Calculator is a small Python 3 program that calculates an approximate render time for both a still image and animation in Blender, when using the Cycles Render Engine. This calculator can determine the approximate render time when you render with Tiles and the Progressive Refine method. (See Below for more info).

Now let’s find out what the different render methods are.


Tiles are those little boxes that come up when rendering. They look like this:

Tile Render

The tiles render one small section at a time. If you want to figure out how to speed up cycles you should check out this post by Blenderguru. In GPU render (explained in the link), the tiles only render one at a time. In CPU render, multiple tiles are rendered at a time. Obviously, the former is easier to determine render time.

You take the time it takes for one tile (say 11 seconds) and multiply that by the amount of all the tiles in the picture (which is shown at the top of the render preview) (and just for an example, we will say we have 52 tiles). Now you have the number of seconds it will take for the render to complete (in our example it is 572 seconds). Divide that number by 60 and you will get the number of minutes it will take (We have approximately 9.5 minutes to wait before our example render is completed).

For CPU calculations, it is pretty much the same except usually it renders about 5 tiles at a time for me.

CPU Tiles

So to figure out the math on that, just find out how long it takes to do 5 tiles then divide it by 5.

Progressive Refine

Progressive Refine is different than Tiles. Progressive Refine renders the entire image in one tile, then adds on to it to make it clearer. The same concept as the tiles, but it does the entire image and is usually a bit slower.

Progressive Refine Render

Here’s the math involved for Progressive Refine. ๐Ÿ˜‰

Say you have 10 samples set for you image render. That is how many “layers” it will have to render of your image to complete. (You can see how many samples you have at the top of the Render Preview Window). Find out how many seconds it takes to render just one of those samples. Multiply the time it takes for 1 sample to render by how many samples you have. (In our example, let’s say we have 10 samples, and it takes 23 seconds to render one sample. 23 x 10 = 230 seconds). Take that answer and divide it by 60 to find out how many minutes it will take to render one image. (230 รท 60 = 3.8 minutes).

Enough with the math! ๐Ÿ˜›

You don’t need to do this math! As I said earlier, le717 and I built a program to calculate all this for you! Just download the program and run it. :). the program can calculate how long it takes to render one image and also how long it takes to render a multi-frame animation.

Remember, this program is not built for Blender Internal render time calculations, but only for Cycles. In the future we may add Blender Internal, and if we do, I’ll tell you. ๐Ÿ˜€


GitHub Project

Download Link

Happy Calculators!




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