How this calculator works
Starter strip is the first course of shingles along the roof edge. It gives the first full course something to seal to and keeps water from getting under the edge. It is sold in bundles that cover a stated number of linear feet, so the count is a division: the length of the eaves and rakes, plus a margin for cuts, divided by the feet one bundle covers, rounded up.
Worked example: 100 ft of eaves and rakes with 5% extra is 105 ft, which is 1 bundle of 120 linear ft. A larger roof with 320 ft of edge needs 3 bundles at 120 ft, or 4 at 105 ft.
Assumptions and sources
- Assumptions used: 120 linear ft per bundle and 5% waste, as you entered; eaves and rakes both counted.
- Coverage per bundle depends on the product, so use the figure on the wrapper. Some shingle makers ask for starter at the rakes as well as the eaves (GAF does for its high-wind warranty), and some roofers cut starter from full shingles at the rakes instead. Ask the supplier whether the shingle bundle count already includes starter.
The formula and a worked example are shown above, so you can check any result by hand. Read how we calculate and check our numbers. Results are estimates for planning: supplier products vary, so check the size printed on the label.
Bundles of starter strip by edge length
With 5% extra. Add the eaves and the rakes before you look up the count.
| Eaves and rakes | 120 ft bundles | 105 ft bundles |
|---|---|---|
| 60 ft | 1 | 1 |
| 100 ft | 1 | 1 |
| 150 ft | 2 | 2 |
| 200 ft | 2 | 2 |
| 250 ft | 3 | 3 |
| 300 ft | 3 | 3 |
| 400 ft | 4 | 4 |
Tips before you buy
- Check the number on the wrapper. Bundles from different makers cover different lengths, and the figure is for the strip laid end to end along the edge.
- Starter strip is cut from the same family of products as the shingles, so buy the one the shingle maker names: a warranty can depend on it.
- Measure the rakes along the slope, which is longer than the horizontal run. A rake on a 6/12 roof is about 12% longer than the run beside it.
- On a hip roof there are no rakes, so the starter goes along the eaves only.
- Keep the leftover starter: it is handy for repairs and for the starter course of a small dormer or porch roof.
Tools & materials for this project
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Frequently asked questions
How many bundles of starter strip do I need?
Add the eaves and the rakes, add 5% for cuts, and divide by the feet a bundle covers. 100 ft of edge takes 1 bundle at 120 linear ft per bundle, and 320 ft takes 3.
How many linear feet does a bundle of starter strip cover?
It depends on the product: about 120 linear ft for GAF Pro-Start and 105 for Owens Corning Starter Strip Plus. The wrapper says.
Does starter strip go on the rakes as well as the eaves?
Often yes. GAF, for example, asks for its starter products at the eaves and the rakes for its high-wind warranty. Check the shingle maker's instructions for your shingle.
Can I cut starter from ordinary shingles?
Many roofers do, by cutting off the tabs of full shingles, but purpose-made starter strip has the sealant on the right edge and is quicker to lay. Follow the shingle maker's instructions.
Is starter strip included in the shingle count?
Not usually. Ask your supplier whether the bundles they quote include starter and ridge cap.
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Related calculators & guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.