Roofing Material Calculator

Calculate shingles, underlayment, starter strip, ridge cap, nails, and drip edge for any roof size and pitch.

Roof Length (ft)

Roof Width (ft)

Roof Pitch

Overhang (ft)

Roof Type

Shingle / Material Type

Waste %

Need to determine your roof pitch first? Use our Roof Pitch Calculator.

Estimated Material Cost

$4,115

2,381 sqft actual area · 27.4 squares (w/ 15% waste)

Flat Area	1,000 sqft
Pitch Multiplier (6/12)	×1.118
Actual Roof Area	2,381 sqft
Roofing Squares	23.8
Squares w/ 15% Waste	27.4
Bundles (3 per square)	83
Underlayment Rolls (400 sqft ea)	6
Starter Strip (33.3 lf ea)	4 pcs
Ridge Cap Bundles	2
Roofing Nails	55 lbs
Drip Edge (10 ft ea)	13 pcs

Cost Breakdown	Amount
Architectural Shingles (27.4 sq × $120)	$3,286
Underlayment (6 rolls × $65)	$390
Starter Strip (4 pcs × $25)	$100
Ridge Cap (2 bdl × $35)	$70
Nails (55 lbs × $3)	$165
Drip Edge (13 pcs × $8)	$104
Total Material Cost	$4,115

info

Mike Callahan:On a hip roof, add 20% waste instead of 15% — you’re cutting every piece at the hip and valley. And order your ice and water shield separately — 2 courses (6 feet) at every eave in cold climates. That’s not in the underlayment count.

Flat area = length × width. Actual area = flat area × pitch multiplier × number of sides, plus overhang perimeter. Squares = actual area ÷ 100. Bundles = squares × 3 (shingles only). Underlayment at 400 sqft/roll, starter strip at 33.3 lf/pc, ridge cap at 33.3 lf/bundle, nails at 2 lbs/square, drip edge at 10 ft/pc. Costs use national average material pricing — get local quotes for final bids.

Frequently Asked Questions

How many bundles of shingles per square?

Three bundles of standard 3-tab or architectural shingles make one roofing square (100 sqft of roof coverage). Some heavy architectural shingles come 4 bundles per square — check the wrapper. Metal and slate are sold by the square, not in bundles, so you order the square count directly from the supplier.

What is a roofing square?

A roofing square is the industry unit for 100 square feet of roof area. A 2,000 sqft roof is 20 squares. All roofing materials — shingles, underlayment, and labor — are priced per square so you can compare costs across different materials on equal terms.

How much waste should I add for a hip roof?

Plan for 15–20% waste on hip roofs compared to 10–15% on gable roofs. Hip roofs have more cuts at every hip line, and each cut creates a piece too small to reuse. Complex roofs with dormers, valleys, or multiple hips may need 20–25%. Metal standing seam typically uses 10% waste since panels are custom-cut to length with fewer offcuts.

Do I need ice and water shield?

In cold climates (IECC zones 5+), building code requires ice and water shield along the first 24 inches past the interior wall line at every eave — typically 2 courses (6 feet up from the edge). It’s also required in valleys and around penetrations (vents, chimneys, skylights). In milder climates, it’s not code-required but still good practice in valleys. Ice and water shield costs $50–80 per roll (75 sqft) and is separate from the felt or synthetic underlayment in this calculator.

How the roofing calculator works

The roofing material calculator produces a full takeoff, field material plus accessories and a cost estimate, from the roof footprint and pitch. You enter the roof length and width in feet, the pitch, the overhang in feet, the roof type (1-sided shed, 2-sided gable, or 4-sided hip), the material, and a waste percentage.

Flat area is length times width. Because a sloped roof covers more surface than its footprint, the tool multiplies the flat area by a pitch multiplier that ranges from 1.014 at a 2/12 pitch to 1.414 at a 12/12 pitch, and 1.118 at the common 6/12. For gable and shed roofs it multiplies the flat area by the pitch factor and the number of sides, then adds the sloped overhang around the eaves. For hip roofs it adds the overhang perimeter to the flat area before applying the pitch multiplier.

The sloped area divided by 100 gives roofing squares. Squares are increased by the waste percentage, then converted to materials: for shingles, 3 bundles per square; underlayment at one roll per 400 square feet; starter strip and ridge cap at 33.3 linear feet per piece; nails at 2 pounds per square; and drip edge at one 10-foot piece per 10 feet of perimeter. Waste defaults to 15 percent, rises to 20 percent for a hip roof, and is capped at 10 percent for metal.

Worked example: a 40-by-25 gable roof at a 6/12 pitch with a 1-foot overhang has a 1,000 square foot footprint. Multiplied by the 1.118 pitch factor over 2 sides gives 2,236 square feet, and the sloped overhang around the 130-foot perimeter adds about 145 square feet, for roughly 2,381 square feet of actual roof. That is about 23.8 squares. Add 15 percent waste and you reach about 27.4 squares, which works out to roughly 83 bundles of architectural shingles, 6 rolls of underlayment, and 13 pieces of drip edge. Get local quotes to firm up pricing before you bid.

Frequently Asked Questions

How does the pitch multiplier work?

A roof surface is longer than its flat footprint because it slopes. The calculator multiplies the flat area by a pitch multiplier, from 1.014 at a 2/12 pitch to 1.414 at a 12/12 pitch (1.118 at a common 6/12), to get the true sloped area. Steeper roofs have a larger multiplier and more surface to cover.

What is a roofing square and how many bundles cover one?

A roofing square is 100 square feet of roof area. For 3-tab and architectural shingles the calculator uses 3 bundles per square. Metal standing seam and slate are ordered by the square, not in bundles, so no bundle count is shown for those materials.

How much waste does it add?

Default waste is 15 percent, which the tool raises to 20 percent when you pick a 4-sided hip roof and caps at 10 percent for metal standing seam. You can set the waste percentage between 5 and 30 percent, but metal is always held to a maximum of 10 percent.

What accessories does the takeoff include?

Beyond the field shingles, the calculator sizes underlayment at 1 roll per 400 square feet, starter strip and ridge cap at 33.3 linear feet per piece, roofing nails at 2 pounds per square, and drip edge at one 10-foot piece per 10 feet of perimeter. Starter strip and ridge cap appear only for shingle materials.