Roofing Calculator
This free roofing calculator turns your home’s footprint and roof pitch into three numbers: roof area, roofing squares, and the bundles of shingles to order. It uses the same math roofers use to build a material list.
Roofing Calculator
Enter your home’s footprint and roof pitch to estimate your roof area, squares, and shingle bundles.
This is an estimate. One square is 100 sq ft, and most architectural shingles cover a square with 3 bundles. Starter shingles and ridge caps are extra. Want an exact count?
Get a Free EstimateHow the Roofing Calculator Works
The math is simple and we show all of it.
- Footprint times pitch factor = roof area. Your roof is bigger than your home’s footprint because it slopes. The steeper the pitch, the bigger the difference.
- Roof area divided by 100 = squares. A square is the roofing unit for 100 square feet.
- Squares times bundles per square = bundles. Most 3-tab and architectural shingles cover a square with 3 bundles. Designer shingles take 4 or 5.
- Add the waste factor. Cuts at edges, valleys, and ridges use extra material. Simple roofs need 10 percent. Cut up roofs need 15 to 20 percent.
Our pitch factors come from real roof geometry, not rounded guesses. A 12/12 roof has 41 percent more surface than its footprint, and the calculator uses that exact number.
How to Find Your Roof Pitch
Pitch is how many inches the roof rises for every 12 inches it runs. A 6/12 roof rises 6 inches per foot.
You do not need to get on the roof. Three safe ways to find it:
- Look at the gable end. If the roof looks like a shallow triangle, it is low. Most newer homes around Vancouver and Portland sit in the 5/12 to 8/12 range.
- Measure in the attic. Hold a level against a rafter, mark 12 inches out, and measure straight up to the rafter. That rise over 12 is your pitch.
- Check your building plans if you have them. Pitch is listed on the roof plan.
| Pitch | How it looks | Roof area vs footprint |
|---|---|---|
| Flat to 3/12 | Nearly flat | About 3% more |
| 4/12 | Gentle slope | About 6% more |
| 5/12 to 6/12 | Typical house | About 12% more |
| 7/12 to 8/12 | Noticeably steep | About 20% more |
| 9/12 to 10/12 | Steep, hard to walk | About 30% more |
| 12/12 | 45 degree angle | About 41% more |
What the Calculator Does and Does Not Include
The bundle count covers field shingles, which is the material on the open faces of the roof. It does not include:
- Starter shingles. They run along the eaves under the first row. Plan on 1 to 2 extra bundles for a typical house.
- Ridge caps. Hips and ridges use their own cap shingles, sold separately. Our ridge vent guide explains what happens at the peak.
- Underlayment, ice and water shield, flashing, vents, and nails. A full roof is a system, not just shingles.
- Labor, tear off, and disposal. For complete installed pricing in our area, see our roof replacement cost guide.
For the full math on bundles, coverage charts, and shingle weights, read our guide to how many bundles of shingles are in a square.
How Accurate Is an Online Roofing Calculator?
Close enough to plan, not close enough to order. A calculator works from your footprint and an estimated pitch. A real measurement accounts for overhangs, dormers, valleys, and every roof plane. On most homes the calculator lands within about 10 percent of a measured roof.
We measure every roof we quote. The measurement and the estimate are free, and you get an exact material list instead of an estimate.
Frequently Asked Questions
How many squares is a 2,000 square foot house?
Usually 22 to 25 squares. The roof is bigger than the house because of pitch and overhangs. A 2,000 square foot footprint with a medium pitch has about 2,240 square feet of roof, which is 22.4 squares.
How many bundles of shingles do I need per square?
Three bundles for almost all 3-tab and architectural shingles. Thick designer shingles take 4 or 5.
Does this calculator work for metal or tile roofs?
The roof area and squares work for any material. The bundle count only applies to shingles. Metal panels and tile are ordered differently.
Should I measure my roof or use a calculator?
Use the calculator to plan and budget. Get a measurement before you order anything. Roofs have overhangs, dormers, and valleys that a footprint estimate cannot see.
What waste factor should I use?
Use 10 percent for a simple gable roof. Use 15 percent if the roof has hips, valleys, or dormers. Use 20 percent for a complex, cut up roof.
Get an Exact Measurement Free
The calculator gets you close. Our measurement gets you a real number and a real price. We measure every roof we quote, and the estimate is free.
Jobin Roofing installs Malarkey shingles across Portland and Southwest Washington.