As part of the research for a post on mak­ing pie dough (https://mynebraskakitchen.com/wordpress/the-pie-dough-chart/), 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 3.175 mm. The sec­ond most com­mon answer appears to be ³⁄₃₂ of an inch, or 2.38 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 this arti­cle: https://mynebraskakitchen.com/wordpress/the-pie-dough-chart/.)

¹⁄₈ inch is slight­ly thick­er than the thick­ness of two pen­nies (3.04 mm) and slight­ly thin­ner than the thick­ness of two quar­ters (3.5 mm), but that’s not much help when rolling out pie dough. A dime stacked on a quar­ter would be even clos­er, 3.10 mm.

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 (1/32 of an inch) 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!