Cedar Shake Calculator
Calculate how many bundles of cedar shakes or shingles you need for a roof at standard exposure, plus total material cost.
How this calculator works
Cedar shakes are sold by the bundle, sized so that 4 bundles cover one roofing square (100 sq ft) at standard exposure — about 25 sq ft per bundle. This calculator divides your roof’s surface area by 25 sq ft to get the bundle count, then rounds up to a whole bundle.
Formula: Bundles = Roof area (sq ft) ÷ 25 sq ft per bundle.
Worked example
A 30 ft × 20 ft roof section (600 sq ft of surface area):
- Area: 30 × 20 = 600 sq ft
- Bundles: 600 ÷ 25 = 24.0 bundles
- At $60/bundle, that’s $1,440.00 before waste.
- With 10% waste added: 24 × 1.1 = 26.4 → rounds up to 27 bundles, or $1,620.00.
Coverage reference
| Roof surface area | Bundles needed (standard exposure) | Squares |
|---|---|---|
| 150 sq ft | 6 bundles | 1.5 squares |
| 600 sq ft | 24 bundles | 6 squares |
| 2,400 sq ft | 96 bundles | 24 squares |
How to measure your roof
Measure each roof plane’s length and width and add the areas together to get total surface area, not just the ground footprint — a pitched roof always has more surface area than its footprint. Confirm your specific shake product’s recommended exposure before ordering, since a shorter exposure than the 4-bundles-per-square standard will require more bundles than this calculator estimates.
Frequently asked questions
How many bundles of cedar shakes cover one roofing square?
At standard weather exposure, 4 bundles of cedar shakes cover one roofing square (100 sq ft), which works out to about 25 sq ft of coverage per bundle. This calculator divides your roof area by that 25 sq ft figure to get your bundle count.
Does changing the exposure change how many bundles I need?
Yes, directly. A shorter exposure (more shake showing per course is smaller) means more courses and more bundles per square, while a longer exposure stretches coverage further and needs fewer bundles — but voids most manufacturer weather warranties if pushed past the recommended maximum for your shake length and grade.
Are cedar shakes and cedar shingles the same product?
No. Shingles are sawn on both faces for a smooth, uniform look and thinner profile, while shakes are split (at least on the exposed face) for a thicker, rustic, hand-hewn texture. Coverage rates are close but not identical — check your specific product's coverage chart if it differs meaningfully from 25 sq ft per bundle.
Why does cedar shake roofing need more waste allowance than asphalt shingles?
Cedar shakes vary naturally in width, so installers cull irregular pieces, double up joints between courses, and cut more at hips, valleys, and ridges than with uniform asphalt shingles. The 10% waste toggle covers typical cutting loss, but complex rooflines with many valleys often need a higher allowance.
Do cedar shake roofs need a special underlayment?
Yes — most cedar shake installations use spaced wood skip sheathing or a breathable synthetic underlayment system rather than solid sheathing with standard felt, since shakes need airflow underneath to dry out and resist rot. Confirm the underlayment system with your supplier before ordering shakes.
How long do cedar shake roofs typically last?
A well-maintained cedar shake roof in a suitable climate typically lasts 25-30 years, though damp, shaded, or high-humidity regions can shorten that lifespan due to moss and rot unless the roof is treated and ventilated properly.
Estimates only. Verify quantities with your supplier before purchasing.