📐 Free Roof Project Estimator

Size, pitch, material, tear-off and underlayment in one instant estimate.

How do you estimate a roofing job?

Two lists. An area list for the field material — shingles, underlayment, sheathing, nails — from the footprint times the pitch multiplier divided by 100. And a length list for the trim: ridge, hip, eave, rake, valley and every wall run. Working from area alone always comes up short.

Get a free instant roof replacement estimate. Enter size, pitch, material, tear-off, underlayment & ventilation to see a 2026 cost range tailored to your ZIP.

The project estimator takes a roof from measurements to a full material list and budget in one pass: area, squares, waste, then every component priced by the square or the linear foot.

What you need before you start

Footprint length and width, measured on the ground to the outside of the eaves and rakes.
Pitch, as rise over 12 inches of run.
Number of existing layers, which sets the tear-off.
Linear feet of ridge, hip, eave, rake and valley — these buy different products from the field area.
Any penetrations: pipes, skylights, chimneys, each of which is flashing the area calculation does not include.

What the estimate covers

Roof pitch converted to angle, slope percentage and area multiplier
Pitch	Angle	Slope %	Multiplier	2,000 sq ft footprint becomes
1/12	4.8°	8.3%	1.0035	2,007 sq ft
2/12	9.5°	16.7%	1.0138	2,028 sq ft
3/12	14.0°	25.0%	1.0308	2,062 sq ft
4/12	18.4°	33.3%	1.0541	2,108 sq ft
5/12	22.6°	41.7%	1.0833	2,167 sq ft
6/12	26.6°	50.0%	1.1180	2,236 sq ft
7/12	30.3°	58.3%	1.1577	2,315 sq ft
8/12	33.7°	66.7%	1.2019	2,404 sq ft
9/12	36.9°	75.0%	1.2500	2,500 sq ft
10/12	39.8°	83.3%	1.3017	2,603 sq ft
12/12	45.0°	100.0%	1.4142	2,828 sq ft
14/12	49.4°	116.7%	1.5366	3,073 sq ft
16/12	53.1°	133.3%	1.6667	3,333 sq ft
18/12	56.3°	150.0%	1.8028	3,606 sq ft
20/12	59.0°	166.7%	1.9437	3,887 sq ft
24/12	63.4°	200.0%	2.2361	4,472 sq ft

The multiplier column is the one that matters: it converts the footprint you measured into the roof surface you have to buy for. A 2,000 square foot footprint at 6/12 is 2,236 square feet of roof.

What it deliberately does not do

It does not quote your job. Labour rates vary more by region than materials do, and roof complexity varies more than either.
It does not guess at decking replacement. Nobody can see the deck until the shingles are off, so that is a contingency, not a line item.
It does not include the permit, which varies by jurisdiction.
It does not send your figures anywhere. The estimate runs in your browser and is not stored.

Frequently asked questions

What do I need before using the project estimator?

Footprint length and width, the pitch, the number of existing layers, and the linear feet of ridge, hip, eave, rake and valley. The last one is what most people forget, and it is what buys the trim.

Does the estimate include labour?

It gives a planning figure. Labour rates vary more by region than materials do, and roof complexity varies more than either, so treat the total as a budget to check quotes against rather than as a bid.

Why does the estimate not include new decking?

Because nobody can see the deck until the shingles are off. Contractors quote a per-sheet rate for whatever bad decking turns up, and that is a contingency rather than a line item.

Are my figures stored anywhere?

No. The estimate runs in your browser. Nothing is uploaded, saved or sent to a contractor.