Shingle Calculator
10.33 squares with 10 percent waste and 3 bundles per square is 35 field bundles, plus 1 starter bundle for 80 feet and 2 ridge bundles for 40 feet.
Last updated . Squares start at 10.33, the roofing-page area before waste. Three bundles per square, 100 feet of starter per bundle, and 25 feet of ridge per bundle are planning figures. No price.
Enter the squares, the waste, the starter length, and the ridge length. Field bundles take the waste. Starter and ridge do not.
Squares from the footprint: roofing calculator. Pitch factor: roof pitch calculator.
Shingle bundles
10.33 squares is the roof area, before waste, from the 40 by 20 foot, 6/12, 1 foot overhang example on the roofing page. Three bundles per square is the planning assumption for standard 3-tab and architectural shingles. Some designer shingles are more. Type the number on the bundle.
Starter starts at 100 ft per bundle and ridge cap at 25 ft per bundle. Those are planning coverages. Waste applies to the field bundles only. No price.
Results
How the bundles are counted
Field bundles = squares × (1 + waste) × bundles per square, rounded up. The squares start at 10.33, which is the roof area before waste for a 40 by 20 foot footprint, a 1 foot overhang, and a 6/12 pitch. Ten percent makes 11.36 squares. At 3 bundles per square, 10.33 × 1.10 × 3 = 34.09, which rounds up to 35.
Three bundles per square is the planning assumption for standard 3-tab and architectural shingles. It is not a brand. Starter bundles round 80 feet up to a 100 foot planning bundle, which is 1. Ridge bundles round 40 feet up to 25 foot planning bundles, which is 2. Waste is not added to those lengths.
Worked example
Leave every field as it opens: 10.33 squares, waste 10 percent, 3 bundles per square, starter 80 ft at 100 ft, ridge 40 ft at 25 ft. With waste reads 11.36. Field bundles read 35. Starter bundles read 1. Ridge bundles read 2.
| Squares | Waste | Per square | Field | Starter | Ridge |
|---|---|---|---|---|---|
| 10.33 | 10% | 3 | 35 | 1 | 2 |
| 10.33 | 15% | 3 | 36 | 1 | 2 |
| 10.33 | 10% | 4 | 46 | 1 | 2 |
| 10.33 | 10% | 3 | 35 | 2 at 120 ft | 1 at 20 ft |
| 10.00 | 10% | 3 | 33 | 1 | 2 |
Frequently asked questions
How many bundles for 10.33 squares?
Leave squares at 10.33, waste at 10 percent, and bundles per square at 3. With waste reads 11.36. Field bundles read 35. Starter stays 80 ft at 100 ft per bundle, so starter bundles read 1. Ridge stays 40 ft at 25 ft per bundle, so ridge bundles read 2. 10.33 is the roof area, before waste, from the 40 by 20 foot, 6/12, 1 foot overhang example.
Why 3 bundles per square?
Three bundles per square is the planning assumption for standard 3-tab and architectural shingles. It is not a brand count. Some designer shingles use more. 10.33 × 1.10 × 3 is 34.09, which rounds up to 35 bundles. Type the number on the bundle if it is not 3.
What does 15 percent waste change?
Set waste to 15. With waste reads 11.88. Field bundles read 36. Starter stays 1 and ridge stays 2. Waste applies to the field only. Starter and ridge use the lengths you type, with no extra percent.
What if the bundle says 4 per square?
Set waste back to 10 and bundles per square to 4. With waste stays 11.36. Field bundles read 46. That is 10.33 × 1.10 × 4 = 45.45, rounded up. Starter stays 1 and ridge stays 2.
How many starter and ridge bundles for a longer eave?
Set bundles per square back to 3. Set starter to 120 and ridge to 20. Field bundles stay 35. Starter bundles read 2, because 120 ÷ 100 rounds up. Ridge bundles read 1, because 20 ÷ 25 rounds up. The 100 ft and 25 ft coverages are planning figures. Read the bundle.
What is a clean 10 square order?
Set squares to 10, starter back to 80, and ridge back to 40. With waste reads 11.00. Field bundles read 33, because 10 × 1.10 × 3 is 33 exactly. Starter bundles read 1. Ridge bundles read 2.
Does this measure the roof?
No. Type the squares. The 40 by 20 foot example is 10.33 squares before waste on the roofing calculator, and 11.36 after 10 percent, which is the with-waste line here. Pitch and degrees are the roof pitch calculator. This page does not add waste to starter or ridge.