Spike's Calculators


Gambrel Roof - Wood Shingles Calculator

Calculate the amount of woood shingles needed to cover a Gambrel roof.

Gambrel style roof   Gambrel style roof

The wood shingles calculation is based on:
Shingles coverage of one roofing square (100sqft) = 4 bundles @ 5" exposure, 1 bundle covers 25 square feet @ 5" exposure.

Gambrel Roof - Shingles

Building Length ft inch
Building Width ft inch
Eaves Overhang inch
Gable Overhang inch
Wall to Upper Pitch Start ft inch
Upper Roof Pitch /12
Lower Roof Pitch /12
Exposure of Shingle inch
Waste %


Roof Area ft²
Ridge Length lineal ft
Shingles to Cover Roof Bundles
Added for Waste Bundles
For Starter Strip Bundles
For Ridge Capping Bundles
Total Amount of Shingles Needed: Bundles


  1. Enter the length of the building. (feet+inches)
  2. Enter the width of the building. (feet+inches)
  3. Enter the overhang of the eaves. (inches)
  4. Enter the overhang of the gable. (inches)
  5. the lower pitch length measured from outside wall to the start of the upper pitch (feet+inches)
  6. Enter the pitch of the upper roof (rise /12")
  7. Enter the pitch of the lower roof. (rise /12")
  8. Exposure of wood shingle (inches)
  9. Waste factor if required. (percentage)


  1. It adds 1 bundle for every 60 lineal feet of perimeter starter course.
  2. It adds 1 bundle for every 25 lineal feet of ridge.
  3. If you are planning to use pre-made capping for the ridge subtract the amount for ridge from total bundles needed.
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