Easy, No-Brainer 3-Step Roofing Estimator
Most roofing calculators and guides have you pulling out formulas and using the Pythagorean theorum and doing calculations with sliderules, when all you really want to know is two very simple things:
- What’s the approximate size of my roof?
- How much approximately will the $@!!*# roof cost?
Why won’t anyone tell that? Beats me. So, the caveat here is that, at the expense of finely granulated accuracy, we are giving you approximate roofing sizes and costs. Average, after all, means after. And while average roofing costs will not apply exactly to you, it will apply in a kinda-sorta way because…it’s average. Got that? The roofing contractors will howl in protest (I can already hear them): But what about flashing, what about New England vs. Arizona, what about seasons? They’re right, but unless they want to start handng out roofing estimates in an article, we’ll have to go with my calculations. Now let’s get started.
Step 1. What’s the Approximate Roof Pitch?
Break it down simple, and say that you’ve got either a low-pitched, medium-pitched, or steeply-pitched house.
Low-Pitch Roof
This can range from absolutely flat to sloped-but-still-easy-to-walk-on. A rambler has this type of roof.
Medium-Pitch Roof
The “average” house. It’s not a low-down 1960s rambler, but it’s not a Gothic-y Victorian, either. This describes most contemporary houses.
Steep-Pitched Roof
Now we’re getting fancy. You don’t need to have a historic hosue to have a steep roof, either. Basically, this means that it’s next to impossible to walk on this roof.
Step 2. How Many Roofing Squares Will the Roof Need?
A roofing square is one-hundred square feet (100 sq. ft.) of shingles.
Because roofers use so many shingles at a time, it’s pointless for them to talk in units smaller than 100 square feet. So, don’t confuse squares with square footage.
Example: Your house has 1,200 square feet and a low pitched roof. So, your total squares are 13.8.
| House Square Footage | Low Pitch | Low to Medium Pitch | Medium to High Pitch | Steep Pitched |
| 700 | 8.05 | 8.75 | 9.8 | 11.9 |
| 800 | 9.2 | 10 | 11.2 | 13.6 |
| 900 | 10.35 | 11.25 | 12.6 | 15.3 |
| 1000 | 11.5 | 12.5 | 14 | 17 |
| 1100 | 12.65 | 13.75 | 15.4 | 18.7 |
| 1200 | 13.8 | 15 | 16.8 | 20.4 |
| 1300 | 14.95 | 16.25 | 18.2 | 22.1 |
| 1400 | 16.1 | 17.5 | 19.6 | 23.8 |
| 1500 | 17.25 | 18.75 | 21 | 25.5 |
| 1600 | 18.4 | 20 | 22.4 | 27.2 |
| 1700 | 19.55 | 21.25 | 23.8 | 28.9 |
| 1800 | 20.7 | 22.5 | 25.2 | 30.6 |
| 1900 | 21.85 | 23.75 | 26.6 | 32.3 |
| 2000 | 23 | 25 | 28 | 34 |
| 2100 | 24.15 | 26.25 | 29.4 | 35.7 |
| 2200 | 25.3 | 27.5 | 30.8 | 37.4 |
| 2300 | 26.45 | 28.75 | 32.2 | 39.1 |
| 2400 | 27.6 | 30 | 33.6 | 40.8 |
| 2500 | 28.75 | 31.25 | 35 | 42.5 |
| 2600 | 29.9 | 32.5 | 36.4 | 44.2 |
| 2700 | 31.05 | 33.75 | 37.8 | 45.9 |
| 2800 | 32.2 | 35 | 39.2 | 47.6 |
| 2900 | 33.35 | 36.25 | 40.6 | 49.3 |
| 3000 | 34.5 | 37.5 | 42 | 51 |
Step 3. Figure the Roofing Cost
All estimated roofing costs include removal and disposal of existing shingles and installation of new shingles. Labor and materials included. Flashing, ice dams, underlayment, repairs, and related items not included.
Composition Shingle Roofing Estimate – Low End
Fiberglass 3-Tab 225 lb. 20 year
Multiply your squares by $143 per square cost.
Example: 35 squares x $143 = $5,005
Composition Shingle Roofing Estimate – High End
Architectural laminated 30 year
Multiply your squares by $171 per square cost.
Example: 35 squares x $171 = $5,985
Cedar Wood Roofing Estimate
16″ Red Label
Multiply your squares by $422 per square cost.
Example: 35 squares x $422 = $14,770
Slate Roofing Estimate
Pennsylvania slate
Multiply your squares by $812 per square cost.
Example: 35 squares x $812 = $28,420