Roof replacement cost is roof area multiplied by an installed price per square foot (or square metre). Asphalt shingles are listed at about $3.40 to $5.95 per sq ft on one ranking guide [CHECK: current local prices]. Enter your roof size, pitch, waste and material above to get the roof area, the roofing squares to order and a price range.

How to use the calculator

1. Pick your units: square feet or square metres.
2. Choose what you measured. Pick “house footprint” if you measured the flat area under the roof. Pick “actual roof surface” if you already have the sloped area.
3. Enter the area.
4. If you used the footprint, pick the roof pitch. Pitch is how many inches the roof rises for every 12 inches of run. A 6/12 roof rises 6 inches per foot.
5. Choose a waste allowance. Use a higher value for hips, valleys and dormers.
6. Pick a material, or choose “custom price” and enter a quote per sq ft or m².
7. Add any flat extra costs, such as disposal or permits. Then press Calculate.

How it works

The tool does four steps.

• Pitch correction. A sloped roof is bigger than the floor plan under it. The tool multiplies the footprint by the square root of (1 + (rise ÷ 12)²). At 6/12 the factor is 1.118. At 12/12 it is 1.414.
• Squares. One roofing square is 100 sq ft. Roof area divided by 100 gives the number of squares.
• Waste. Cuts, offcuts and mistakes use extra material. Squares × (1 + waste %) gives the squares to order.
• Cost. Roof area × price per sq ft gives the low and high cost. Your extras are added on top. Installed prices are normally quoted on measured roof area, so waste is not added to the price.

In metric mode the tool converts to square feet using 1 m² = 10.7639 sq ft. The preset prices are shown in US dollars.

Worked example

A house has a 1,500 sq ft footprint. The roof is a simple gable at 6/12 pitch. You want asphalt shingles and a 10% waste allowance.

1. Pitch factor at 6/12: 1.118.
2. Roof area: 1,500 × 1.118 = about 1,677 sq ft.
3. Squares: 1,677 ÷ 100 = 16.77.
4. Squares to order: 16.77 × 1.10 = about 18.45.
5. Low cost: 1,677 × $3.40 = about $5,702.
6. High cost: 1,677 × $5.95 = about $9,978.

The midpoint is about $7,840. A real quote may fall outside this range because of local labour rates, roof height and repairs [CHECK: local contractor quotes].

Reference table

Price ranges below come from a roofing cost guide that lists US figures per sq ft of roof [CHECK: figures are dated and US-based].

Material	Price per sq ft	Cost for 1,700 sq ft roof
Asphalt shingles	$3.40 – $5.95	$5,840 – $10,100
Metal roofing	$6.00 – $24.50	$10,245 – $41,640
Tile roofing	$6.30 – $12.30	$10,665 – $20,900
Wood shakes / shingles	$6.00 – $9.15	$10,230 – $15,500
Slate roofing	$23.49 – $31.77	$39,925 – $54,020

Pitch correction factors for common slopes:

Pitch	Angle	Multiply footprint by
4/12	18.4°	1.054
6/12	26.6°	1.118
8/12	33.7°	1.202
10/12	39.8°	1.302
12/12	45.0°	1.414

Tips and common mistakes

• Do not use floor area. Living space is not roof area. Overhangs add roof. Garages and porches may add more. Measure the roof or the footprint.
• Do not skip pitch. A steep roof can be 40% larger than its footprint.
• Measure complex roofs in parts. Split the roof into simple shapes, find each area, then add them. Enter the total as actual roof surface.
• Raise waste for hips and valleys. A plain gable wastes less than a cut-up roof.
• Add the extras. Tear-off, disposal, permits and rotten decking repair may not be in the per-sq-ft price. Ask each contractor what is included.
• Compare written quotes. Use this result as a sanity check, not as a bid.
• Budget for the whole project. If the chimney is near the roof, check our chimney repair cost calculator. For interior work afterwards, try the hardwood floor refinishing cost calculator.

This page gives estimates only. Read our disclaimer before relying on any figure.

FAQ

How much is a new roof on a 2000 sq ft house?

If the roof surface is 2,000 sq ft and you use asphalt shingles at $3.40 to $5.95 per sq ft, the range is about $6,800 to $11,900. Many houses with 2,000 sq ft of living space have a smaller roof footprint, so measure your own roof or use the pitch option.

How much is 1500 sq ft of shingles?

1,500 sq ft of roof is 15 roofing squares. With 10% waste you would order about 16.5 squares. At the ranking-page asphalt range this installs for roughly $5,100 to $8,925 [CHECK: local prices].

What is the average cost to replace a roof on a 1200 sq. ft. house?

Enter your roof area, not your floor area. A 1,200 sq ft footprint at 6/12 pitch gives about 1,342 sq ft of roof. Asphalt at $3.40 to $5.95 per sq ft comes to about $4,563 to $7,985.

How much does a 20×20 roof cost?

A 20 ft by 20 ft footprint is 400 sq ft. At 6/12 pitch the roof is about 447 sq ft. Asphalt at $3.40 to $5.95 per sq ft is about $1,520 to $2,661, before extras such as tear-off or repairs.

What is a roofing square?

One roofing square covers 100 square feet of roof. Contractors often quote materials per square.

Should I add waste to the cost?

Add waste to the amount of material you order. Installed prices are normally quoted on measured roof area, so this tool applies the price to roof area and uses waste for the squares to order.