Short and simple, use 32 times the number of blocks you want something( e.x. rotating and moving block) to cover, and don't forget to use Ctrl to make it look pixel perfect.
The longer explanation:
After doing some experimenting, I've discovered the pixels of one tile are 32 (Measured by a rotating and moving block.) pixels. If you need an example, it is here:
As in this small demonstration, you can see that after modifying the size of the blocks to 32 and 64, any multiple of 32 works, and they are perfectly aligned on the lines, so I know that it means size 32 of a block equals one tile.
If you want multiples of 32:
1: 32
2: 64
3: 96
4:128
5: 160
6: 192
7: 224
8: 256
9: 288
10: 320
And you can just use calculator for the rest.
Note: The numbers on the side mean how many tiles the block will be.