As part of the research for a forthcoming post on making pie dough, I’ve been doing some testing on pie dough thickness.
Various sources give different answers as to how thick the dough for pie crust should be. The most common answer appears to be 1/8 inch, or about 4 mm. The second most common answer appears to be 3/32 of an inch, or 3 mm.
If that doesn’t seem like a big difference, it isn’t and yet it is. 1/32 of an inch is pretty tough to see, but the difference between 3/32 and 1/8 is 25%. So you could wind up with too much pie dough or not enough. (Computing the amount of pie dough to make is the focus of the article I’ve been working on for a while, which I hope to have finished in the next few weeks.)
1/8 inch is slightly thicker than the thickness of two pennies and slightly thinner than the thickness of two quarters, but that’s not much help when rolling out pie dough.
A number of sources sell pie dough wands that can be used to make sure your pie dough is rolled out to the desired thickness. They commonly come in 1/16, 3/32 and 1/8 inch increments, or 2mm, 3mm and 4mm. They’re made from a variety of materials, hard plastics, softer plastics like silicone and even wood, though the wood ones are harder to find. They also make rings in various thicknesses that go around your rolling pin, but I’ve always thought those got in my way.
I’ve got a set of the silicone pie wands, and they work fairly well, the pie dough comes out a pretty consistent thickness, but with one caveat. When I roll out pie dough, I press down hard enough that the soft silicone compresses a bit, so though I’m using the 1/8 inch thick wands, my pie dough is closer to 3/32 of an inch thick.
How do I know this? A little household/kitchen science.
I looked around for an easy way to measure pie dough thickness differences, since most people, myself included, don’t have a clean set of auto mechanic’s feeler gauges lying around. I’ve got a digital caliper (sold in bead shops) that measures in .01 inch increments, which is good for measuring 1/8 inch or larger thicknesses or lengths, but it doesn’t do a very precise job measuring very small increments, such as ones under 1/32 of an inch (0.03125).
Add to that the problem that pie dough is even softer than silicone, so measuring it without squeezing it is another challenge. Even picking it up to measure it could stretch it slightly. I needed a way to check the thickness of my pie dough against the pie wands without disturbing it.
It turns out many of us have an item in our house that is consistently very thin–paper for a printer or home copier. I measured a full package of copy paper (800 sheets of 24 pound paper) and got 3.49 inches, or 0.0043625 inches per sheet. That means that 1/8 inch should be between 28 and 29 sheets of paper, and 1/32 of an inch should be slightly more than 7 sheets of paper.
I checked this by stacking 28 sheets of paper next to the 1/8″ silicone pie wand. I could feel a slight difference in thickness with my fingers. When I added a 29th sheet, I could still feel a slight difference, but now in the other direction.
With this measuring tool in hand, I rolled out a pie crust using the 1/8″ wands and stacked paper on top of it until I could just barely feel a difference between the combined height of the pie dough and the sheets of paper and the 1/8″ thick pie wand. When I added the 7th sheet of paper, it changed which way my fingers felt the change in height. So I know my pie dough is slightly thicker than 3/32 inch.
And the pie came out great!