Roofing & Exterior Calculators
Roof area is footprint × pitch multiplier, where the multiplier is √(1 + (rise ÷ 12)²). A 40 × 30 ft house with a 6/12 roof covers about 1,342 sq ft, or 13.4 squares. Fences, decks and siding follow the same idea: measure, add waste, and round up to units.
Roofing Calculator
Roof area in squares and bundles of shingles from pitch.
Roof Pitch Calculator
Pitch in x/12, angle in degrees and area multiplier.
Fence Calculator
Posts, rails and pickets for a wood fence.
Deck Calculator
Deck boards, joists and screws for a new deck surface.
Siding Calculator
Squares of siding for walls and gables.
Outside the house
Exterior projects face weather and inspections, so accurate numbers protect both your budget and your schedule. Roof estimates start from the footprint and the slope; siding from the wall perimeter and gables; fences and decks from straight-line runs. Permits are common for reroofing, attached decks and tall fences, and setbacks or HOA rules may limit where you can build. Order a modest overage, since a second delivery costs more.
Which calculator do I need?
- Roofing: shingle squares and bundles for a reroof or new roof.
- Roof pitch: turning a rise and run measurement into x/12, degrees and the area multiplier.
- Fence: wood privacy or picket fences: posts, rails and pickets.
- Deck: surface boards, joists and screws for a new or resurfaced deck.
- Siding: vinyl, fiber cement or wood cladding for walls and gable ends.
Before you buy
Check the weather window before tearing off shingles or starting siding, and stage materials close to where they will be used. Order trim pieces such as drip edge, ridge cap, J-channel and starter strip at the same time as the main product. Mark fence lines from a survey, not from an old fence. On ladders and roofs, use fall protection and never work alone.
Frequently asked questions
What is a roofing square?
100 sq ft of roof surface, usually three bundles of standard shingles.
Do I need a permit for a fence?
Often, especially above 6 ft or near property lines. Check with your city and HOA.
How far apart should deck joists be?
Typically 16 in on center, or 12 in for diagonal decking.
How do I find my roof pitch?
Measure the rise over 12 in of run, or use the roof pitch calculator.