ContractorHandbook

5/12 Roof Pitch: Angle, Multiplier and What It Means

Angle

22.6 degrees

5 inches of rise for every 12 inches of run, over a 1,200 square foot footprint.

angle12 in of runrise, inmultiplierroot of (rise squared + 144) / 12 = multipliersame number as a degree angle and as a percent grade
Pitch, angle, grade and slope multiplier are four ways of saying one thing, and a drawing is the fastest way to see that. Everything on the page comes out of the same triangle: 12 inches of run along the bottom, the rise up the side.

How that number is worked out

These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.

  • Rise5 in per 12 in run
  • Footprint area, 0 to skip1200 sq ft

Slope multiplier1.08 x footprint

Pitch5/12
Slope multiplier1.08 xmultiply footprint by this
Angle22.6 degrees
Grade41.7%
Rafter length per 12 ft of run13 ft
Roof surface for 1,200 sq ft footprint1,300 sq ft
That is13 squares

Pitch compared

The whole table, so you do not have to come back for the next one.

PitchSlope multiplierAngleGrade
2/121.01 x footprint9.5 degrees16.7%
3/121.03 x footprint14 degrees25%
4/121.05 x footprint18.4 degrees33.3%
5/121.08 x footprint22.6 degrees41.7%
6/121.12 x footprint26.6 degrees50%
7/121.16 x footprint30.3 degrees58.3%
8/121.2 x footprint33.7 degrees66.7%
9/121.25 x footprint36.9 degrees75%
10/121.3 x footprint39.8 degrees83.3%
12/121.41 x footprint45 degrees100%

What else matters here

A 5/12 pitch is 22.6 degrees. It is a standard slope with no special underlayment requirement and it is still walkable for most people, though the footing is noticeably less certain than on a 4/12 when the surface is damp or dusty with granules.

The multiplier is 1.08, so a 1,200 square foot footprint becomes 1,300 square feet of roof, an even 13 squares. Eight percent is enough to matter on a material order and enough to matter again on a tear off, since you pay to take the same area off.

It gives a little more attic height than a 4/12 without pushing the ridge up far enough to change the look of the house, which is why it turns up so often on additions that have to match an existing roof line.

What this calculator assumes

  • Pitch is written as rise over a 12 inch run. A 6/12 roof climbs 6 inches for every 12 inches across.
  • The slope multiplier converts flat footprint area into real roof surface. It is the number that decides whether you order enough shingles.
  • Below 2/12, shingles are not rated. Below 4/12, most manufacturers require a double underlayment. Over 8/12 you are on roof jacks and the labor price changes.

Questions people ask

What is 5/12 in degrees?

22.6 degrees, which is a 41.7 percent grade.

Can you walk on a 5/12 roof?

Most roofers will, in dry conditions with clean soles. It is the pitch where crews start thinking about jacks rather than reaching for them automatically.

What is the slope multiplier for?

Multiply the flat footprint of the building by it to get the real surface area of the roof. A roof plan gives you the footprint, and the multiplier turns it into the area you actually have to cover.

Different numbers?

The roof pitch calculator takes any dimensions you like and hands back the same list.

Other common sizes