Gable Area Chart by Width and Pitch

Every gable width from 16 to 48 feet at five pitches, so the triangle nobody can reach with a tape stops being a guess.

A gable is a triangle, and its area is the width squared times the pitch divided by 48. The 48 is doing two things at once: dividing by two because it is a triangle, and by twenty four to turn inches of rise per foot into feet of height. That is the whole reason you never have to climb up and measure the peak.

Width is squared, which is the part that surprises people. A 40 foot gable is not a third larger than a 30 foot gable, it is nearly twice as large. That is why gables blow an estimate on a wide house and barely register on a narrow one.

Area of one gable, square feet

Gable width	4/12	6/12	8/12	10/12	12/12
16 ft	21	32	43	53	64
18 ft	27	41	54	68	81
20 ft	33	50	67	83	100
22 ft	40	61	81	101	121
24 ft	48	72	96	120	144
26 ft	56	85	113	141	169
28 ft	65	98	131	163	196
30 ft	75	113	150	188	225
32 ft	85	128	171	213	256
34 ft	96	145	193	241	289
36 ft	108	162	216	270	324
38 ft	120	181	241	301	361
40 ft	133	200	267	333	400
42 ft	147	221	294	368	441
44 ft	161	242	323	403	484
46 ft	176	265	353	441	529
48 ft	192	288	384	480	576

One gable. Most houses have two, so double it before ordering. A cross gable, a dormer or a gabled porch is another triangle at its own width and its own pitch.

Two gables in squares of siding, waste included

Gable width	4/12	6/12	8/12	10/12	12/12
16 ft	0.5	0.7	1	1.2	1.4
18 ft	0.6	0.9	1.2	1.5	1.8
20 ft	0.7	1.1	1.5	1.9	2.2
22 ft	0.9	1.4	1.8	2.3	2.7
24 ft	1.1	1.6	2.2	2.7	3.2
26 ft	1.3	1.9	2.5	3.2	3.8
28 ft	1.5	2.2	2.9	3.7	4.4
30 ft	1.7	2.5	3.4	4.2	5
32 ft	1.9	2.9	3.8	4.8	5.7
34 ft	2.2	3.2	4.3	5.4	6.5
36 ft	2.4	3.6	4.8	6	7.3
38 ft	2.7	4	5.4	6.7	8.1
40 ft	3	4.5	6	7.5	9
42 ft	3.3	4.9	6.6	8.2	9.9
44 ft	3.6	5.4	7.2	9	10.8
46 ft	3.9	5.9	7.9	9.9	11.8
48 ft	4.3	6.5	8.6	10.8	12.9

Squares for a pair of gables with 12 percent waste. Gable siding wastes more than wall siding does, because every course meets the rake at an angle and the offcut is a triangle that will not start another course.

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Getting the width and the pitch without a ladder

The width is the wall the gable sits on, measured at the eave. On a house with the ridge running front to back, that is the side wall. On one with the ridge running side to side, it is the end wall. It is almost always the shorter of the two dimensions.

The pitch you can take from the ground at the rake. Hold a level against the rake board, mark twelve inches along it, and measure straight down to the roof line from that mark. If you can get into the attic, do the same against the underside of a rafter.

Why gable siding wastes more

On a wall, a course runs corner to corner and the offcut from one wall starts the next one. In a gable every course is shorter than the one below it and both ends are cut on the rake angle, so what comes off is a wedge that fits nowhere.

Twelve percent is in the second table and it is about right for a plain gable. A gable done in shake, scallop or board and batten as an accent, which is common, runs higher, and the accent material is usually the expensive one.

Gables are where the labor hides too

The material in a pair of gables is two to four squares on most houses, which is not a large number. The time is not proportional to it. Gable work is ladder or staging work at the top of the wall, every course needs two rake cuts rather than none, and the peak course is a single piece of trim that takes as long as a whole wall course below it.

If you price siding by the square, price gable squares higher than wall squares. They are not the same work.

Questions people ask

How do you calculate the square footage of a gable?

Width squared, times the pitch, divided by 48. A 30 foot wide gable at 6/12 is 30 times 30 times 6, divided by 48, which is 112.5 square feet, and the table above rounds that to 113. Two of them are 225.

How much siding for a gable end?

Find the width in the table above and read across to your pitch. A 30 foot gable at 6/12 is 113 square feet, a little over one square, and a pair of them comes to two and a half squares once waste is in. The same pair at 12/12 is five squares.

Do I need the height of the peak?

No, and that is the point of the formula. The pitch already contains the height: at 6/12 the peak of a 30 foot gable is 7.5 feet above the eave, and dividing by 48 instead of 24 works that out for you while it halves the rectangle.

What about a hip roof?

A hip roof has no gables at all, so the gable line is zero and the walls are the whole job. A hip and gable combination has however many triangles it has, each measured at the wall it sits on.

More reference charts

Siding squares chartTen wall perimeters against six wall heights, with the waste already added, so you can price the walls before you have measured a single gable.Roof pitch chartEvery pitch from 1/12 to 24/12, with the angle, the multiplier you have to apply to a footprint, and the rafter length that goes with it.Roof squares chartFifteen common footprints against six pitches, so you can find a house roughly the size of the one in front of you and see the squares before you measure anything.Concrete slab chartSeventeen slab sizes from a 4 x 4 pad to a 30 x 40 shop floor, at three thicknesses, with the bag counts next to the yardage.Concrete bag chartFrom a quarter of a yard to five yards, in quarter yard steps, with the bag count for both common bag sizes.Board foot chartBoard feet per piece for every common nominal size from 1x4 to 8x8, at six lengths, so you can price a list that is quoted per board foot.

See all 30 reference charts.