How Many Shingles Do You Need for a 1500 Sq Ft Roof?

Planning a roofing project? The last thing you want is to run short on shingles mid-job or overbuy and waste money. This guide breaks down the exact math for calculating shingle quantities for any roof size.

The Quick Answer

For a 1500 sq ft house with a standard 4/12 pitch roof:

• 18 to 20 squares of shingles (roof square footage is larger than floor space)
• 54 to 60 bundles of 3-tab shingles (3 bundles per square)
• 60 to 65 bundles of architectural shingles (3.33 bundles per square)

For a 2000 sq ft house with a 6/12 pitch:

• 26 to 28 squares of shingles
• 78 to 84 bundles of 3-tab shingles
• 87 to 93 bundles of architectural shingles

The Formula

Roofing isn’t just your house square footage. You need to account for roof pitch, waste, and overlap.

Step 1: Calculate Roof Squares

A “square” in roofing = 100 square feet of roof surface.

For a simple gable roof: Roof area = (Length × Width × 2) ÷ Cos(pitch angle)

For complex roofs, measure each plane separately and add them up.

Step 2: Apply Pitch Multiplier

Steeper roofs have more surface area. Use this multiplier:

Roof Pitch	Multiplier
3/12	1.03
4/12	1.05
5/12	1.08
6/12	1.12
7/12	1.16
8/12	1.20
9/12	1.25
10/12	1.30
12/12	1.41

Example: 1500 sq ft house, 4/12 pitch

• Floor area = 1500 sq ft
• Roof area (gable) = 1500 × 1.05 = 1575 sq ft
• Squares = 1575 ÷ 100 = 15.75 squares

Step 3: Add Waste Factor

Always order 10 to 15% extra for the following reasons:

• Cuts around vents, chimneys, valleys
• Starter strips along eaves and rakes
• Damaged shingles
• Future repairs (match dye lots)

Final calculation: 15.75 × 1.10 = 17.3 squares, which rounds up to 18

Reference Chart: Common House Sizes

House Size	Roof Pitch	Roof Squares	3-Tab Bundles	Architectural Bundles
1000 sq ft	4/12	12–13	36–39	40–43
1500 sq ft	4/12	18–20	54–60	60–65
1500 sq ft	6/12	19–21	57–63	63–70
2000 sq ft	4/12	24–26	72–78	80–87
2000 sq ft	6/12	26–28	78–84	87–93
2500 sq ft	6/12	32–34	96–102	107–113
3000 sq ft	8/12	42–45	126–135	140–150

Includes 10% waste factor

Shingle Types: 3-Tab vs Architectural

3-Tab Shingles

• Coverage: 3 bundles per square
• Cost: $25 to $35 per bundle ($75 to $105 per square)
• Lifespan: 15 to 20 years
• Profile: Flat, uniform appearance
• Weight: ~200 lbs per square

Architectural (Dimensional) Shingles

• Coverage: 3 to 4 bundles per square (varies by brand)
• Cost: $35 to $50 per bundle ($105 to $200 per square)
• Lifespan: 25 to 30 years
• Profile: Textured, shadow lines (mimics wood shake)
• Weight: ~250 to 300 lbs per square

Pro tip: Architectural shingles are worth the upfront cost because they last 50% longer and boost resale value more than 3-tab.

Pro Tips for Ordering Shingles

1. Measure Roof Pitch Accurately

Use the phone app method with these steps:

• Download a digital level app
• From attic, place phone on rafter
• Record the pitch (e.g., “18.4°” = ~4/12 pitch)

Or use the carpenter’s method with these steps:

• 12” level on the roof
• Measure vertical rise at the 12” mark
• 4” rise = 4/12 pitch, 6” rise = 6/12 pitch

2. Order Extra for Complex Roofs

Standard waste factors are as follows:

• Simple gable: 10%
• Hip roof: 12%
• Multiple valleys/dormers: 15%
• Diagonal/diamond patterns: 20%

3. Don’t Forget Starter Shingles

Starter strips run along eaves and rakes (gable edges). You need the following:

• Linear feet of eaves + rakes
• Divided by bundle coverage (~100 LF per bundle)

Example: 40’ × 25’ house

• Eaves: 40’ × 2 = 80 LF
• Rakes: 25’ × 2 = 50 LF
• Total: 130 LF ÷ 100 = 2 bundles of starter

4. Buy Ridge Cap Separately

Ridge cap covers the peak. You need the following calculation:

• Linear feet of ridge × 1.10 (waste)
• Divided by bundle coverage (~35 LF per bundle)

Example: 40’ ridge

• 40 × 1.10 = 44 LF ÷ 35 = 2 bundles of ridge cap

5. Check Weight Limits

Most roofs can handle one layer of architectural shingles (250 to 300 lbs per square). But if re-roofing over existing shingles:

• Code allows max 2 layers in most areas
• Weight: 2 layers = 400 to 600 lbs per square
• Older homes may need structural evaluation

Always tear off old shingles if you already have 2 or more layers.

Underlayment Matters

Shingles don’t work alone. You also need the following materials:

Felt underlayment (15# or 30#):

• Covers entire roof deck before shingles
• One roll = 400 sq ft (15#) or 200 sq ft (30#)
• For 1500 sq ft roof: 4–5 rolls of 15# felt

Synthetic underlayment (better):

• Lighter, stronger, longer-lasting than felt
• One roll = 1000 sq ft
• For 1500 sq ft roof: 2 rolls

Ice and water shield:

• Required along eaves (first 3 to 6 feet) in cold climates
• Prevents ice dam leaks
• One roll = 200 sq ft

Common Mistakes to Avoid

1. Forgetting the Pitch Factor

Roof surface area doesn’t equal floor area. A steep 12/12 pitch roof has 41% more surface than the house footprint. Always apply the pitch multiplier.

2. Not Ordering Enough Starter Strips

Beginners forget that starter shingles run the entire perimeter of eaves + rakes, not just the eaves. Missing this adds 30 to 50% more linear feet.

3. Mixing Dye Lots

Shingle color varies slightly between manufacturing runs. If you run short and order more later, the new bundles may not match. Order 10% extra upfront and return unopened bundles if you don’t use them.

4. Ignoring Ventilation Requirements

Code requires 1 sq ft of ventilation per 150 sq ft of attic space. If adding ridge vent, you’ll lose approximately 1 square of shingles to the vent cutout, so account for this in your order.

5. Skipping Hip & Ridge Cap

Regular shingles cut into thirds don’t equal proper ridge cap. Purpose-made ridge cap shingles seal better and last longer. Budget for 2 to 3 bundles for a typical house.

When to Call a Pro

DIY shingle replacement works for the following situations:

• Simple gable roofs under 2000 sq ft
• Pitch under 6/12 (safe to walk on)
• Single-story homes

Hire a contractor for the following situations:

• Pitch over 8/12 (dangerous without harnesses)
• Three-story homes
• Complex valleys, turrets, or dormers
• Full tear-off of multiple layers

Frequently Asked Questions

How many bundles of shingles are in a square?

3-tab shingles require 3 bundles per square, while architectural (dimensional) shingles require 3 to 4 bundles per square depending on the brand. A square equals 100 square feet of roof coverage. Always check the manufacturer’s coverage specifications on the bundle packaging.

How much waste should I add when ordering shingles?

Add 10% waste for simple gable roofs, 12% for hip roofs, 15% for roofs with multiple valleys or dormers, and 20% for diagonal or diamond patterns. This accounts for cuts around vents and chimneys, starter strips, damaged shingles, and future repairs from matching dye lots.

Do I need to remove old shingles before installing new ones?

Code allows a maximum of 2 layers of shingles in most areas. If you already have 2 or more layers, you must tear off to the roof deck. Even with one layer, tearing off is recommended because it allows inspection of the roof deck, improves ventilation, reduces weight load, and extends the new roof’s lifespan.

What’s the difference between roof pitch 4/12 and 6/12?

The first number is the vertical rise in inches for every 12 inches of horizontal run. A 4/12 pitch rises 4 inches per foot (moderate slope), while a 6/12 pitch rises 6 inches per foot (steeper). Steeper pitches have more surface area. A 6/12 roof has 12% more shingles than a 4/12 roof of the same house footprint.

Should I choose 3-tab or architectural shingles?

Architectural shingles are worth the investment for most homes. They cost 30 to 40% more upfront but last 25 to 30 years compared to 15 to 20 years for 3-tab. They also provide better wind resistance and curb appeal, and significantly boost resale value. The extra cost pays for itself through longevity and reduced replacement frequency.

Use our roofing calculator to get instant shingle quantities for your exact roof dimensions and pitch.