Pie Crust Ratio Calculator Formula

Understand the math behind the pie crust ratio calculator. Each variable explained with a worked example.

Formulas Used

Flour

flour_total = flour_weight * crust_type * pow(pan_diameter / 9, 2)

Fat (Butter/Shortening)

fat_total = flour_weight * crust_type * pow(pan_diameter / 9, 2) * 2 / 3

Ice Water

water_total = flour_weight * crust_type * pow(pan_diameter / 9, 2) / 3

Salt

salt_total = flour_weight * crust_type * pow(pan_diameter / 9, 2) * 0.02

Variables

VariableDescriptionDefault
pan_diameterPie Pan Diameter(inches)9
crust_typeCrust Coverage1
flour_weightFlour for Single Crust(grams)180
scaleDerived value= crust_type * pow(pan_diameter / 9, 2)calculated

How It Works

How to Calculate Pie Crust Ingredients

The 3:2:1 Ratio

3 parts flour : 2 parts fat : 1 part water (by weight)

This classic ratio produces a flaky, tender crust. The flour provides structure, cold fat creates flaky layers, and ice water binds the dough.

Scaling for Pan Size

The base recipe is calibrated for a 9-inch pan. Scale by the square of the diameter ratio: (pan / 9) squared. A double crust uses twice the material.

Tips

Keep butter and water ice cold. Overworking the dough develops gluten, making the crust tough instead of tender.

Worked Example

A double-crust pie in a 9-inch pan, 180 g flour base per single crust.

pan_diameter = 9crust_type = 2flour_weight = 180
  1. 01Scale factor = 2 x (9/9)^2 = 2
  2. 02Flour = 180 x 2 = 360 g
  3. 03Fat = 360 x 2/3 = 240 g (about 1 cup butter)
  4. 04Water = 360 / 3 = 120 g (about 1/2 cup)
  5. 05Salt = 360 x 0.02 = 7.2 g (about 1.5 tsp)

Frequently Asked Questions

Can I use all butter or all shortening?

All butter gives the best flavor but melts faster, making the dough harder to handle. All shortening is easier to work with and very flaky but less flavorful. A 50/50 blend is a popular compromise.

Why does pie crust need to rest in the fridge?

Chilling for at least 30 minutes re-firms the butter, relaxes the gluten, and makes the dough easier to roll. This results in a flakier, more tender crust that holds its shape during baking.

How do I prevent a soggy bottom crust?

Blind-bake the bottom crust (bake with pie weights for 15 minutes at 400°F, then remove weights and bake 5 more minutes). For fruit pies, brush the bottom with egg white before filling.

Ready to run the numbers?

Open Pie Crust Ratio Calculator