Rolling Offset Calculator

The rolling offset formula is a two-step Pythagorean calculation. Step 1: find the true offset T = sqrt(offset^2 + advance^2), the diagonal across the rolled plane. Step 2: travel = T x cosecant(fitting angle), the center-to-center pipe length between the two fittings. Example: a 12 in vertical offset rolled with a 9 in horizontal advance using 45 degree elbows gives T = sqrt(12^2 + 9^2) = 15.00 in, then travel = 15 x 1.4142 = 21.2132 in (21.21 in, or 21 3/16"). The pipe rolls at 53.13 degrees from horizontal. If you want to know how to calculate rolling offset by hand, that is the whole method: Pythagoras first, then the rolling offset multiplier. The calculator above runs the rolling offset hypotenuse formula instantly in imperial or metric units.

Open the Rolling Offset tab, enter the vertical offset and the horizontal advance (in inches, feet, millimeters, centimeters, or meters), pick your fitting angle (45 degrees is the trade standard), and read the results: true offset, travel length, run along the pipe axis, and roll angle. This travel calculator plumbing workflow replaces the old two-step hand math. Example: offset 12 in, advance 9 in, 45 degree fittings gives true offset 15.00 in and travel 21.21 in. Switch to the Pipe Cut tab and subtract your fitting allowances to get the exact cut length.

Yes. For rolling offset 45 degree elbows the multiplier is exactly the square root of 2 (1.4142), so travel = true offset x 1.4142. If the offset and advance are equal, the math collapses beautifully: a 6 in offset rolled with a 6 in advance gives T = sqrt(6^2 + 6^2) = 8.4853 in, and travel = 8.4853 x 1.4142 = exactly 12.00 in. That is why 45 degree rolling offset work is the fastest in the field: measure one side, and the 45 degree rolling offset shortcut gives you the travel without a calculator. The tool above uses the exact 1.4142 constant (trade tables round it to 1.41).

A rolling offset multiplier is the cosecant of the fitting (or bend) angle: multiplier = 1 / sin(angle). It converts the offset depth into the hypotenuse distance between bends or fitting centers. Common values: 10 deg = 5.76, 22.5 deg = 2.61, 30 deg = 2.00, 45 deg = 1.4142, 60 deg = 1.15. For example, a 4 in conduit offset with 30 degree bends needs the marks 8.00 in apart (4 x 2.00). The emt offset bend multiplier chart on this page lists the full table from 5 to 60 degrees, alongside the offset multiplier chart conduit benders print on the tool itself. Every entry matches 1/sin(angle) rounded to trade precision.

Yes. A rolling offset EMT run combines both methods on this page: use the Rolling Offset tab to get the travel through 3D space, or use the Conduit Offset Bend tab for a flat EMT offset with a hand bender. Example: to clear a 4 in obstruction with 30 degree bends, the rolling offset emt math is marks 4 x 2.00 = 8.00 in apart, with exact shrink 1.0718 in (the field rule of thumb is 1.00 in at 1/4 in per inch). Any offset bend calculator that only does Pythagoras is missing this: real conduit work needs the cosecant marks and the shrink correction, which this conduit rolling offset tool computes together.

With 22.5 degree fittings or bends, the multiplier is 1/sin(22.5 deg) = 2.6131 (trade tables print 2.61). Travel = true offset x 2.6131. Example: a 3 in offset depth bent at 22.5 degrees needs bend marks 3 x 2.6131 = 7.8394 in apart, and the conduit shrinks 0.5967 in (field rule: 0.56 in at 3/16 in per inch). A 22.5 degree rolling offset is gentler than 45 degrees, so wire pulls easier through it, at the cost of a longer travel. Use the rolling offset angle calculator tab to compare 22.5, 30, and 45 degree options side by side.

Yes, the Reference tab on this page is a full rolling offset chart: every bend angle from 5 to 60 degrees with its exact cosecant multiplier, the rounded trade-table multiplier, and the shrink per inch of offset (both the exact geometric value and the field rule of thumb). For instance, the chart shows 30 deg -> multiplier 2.00 with shrink 0.268 in/in (field: 1/4 in), and 45 deg -> multiplier 1.4142 with shrink 0.414 in/in (field: 3/8 in). Bookmark the page and the rolling offset chart is always one tap away.

Travel is measured center-to-center between fittings, but you cut the pipe shorter: cut length = travel - (takeoff 1 + takeoff 2), where each takeoff is the fitting's center-to-face allowance. This is what the rolling offset take off calculator tab does. Example: travel 21.21 in with two 45 degree elbows taking 1.5 in each gives a cut of 21.2132 - 3.00 = 18.2132 in (18.21 in, or 18 3/16"). The pipe offset travel length formula gives you the center-to-center number; the rolling offset fitting allowance is what you subtract to get the piece you actually cut.

Yes. Every input accepts inches, feet, millimeters, centimeters, or meters, and the output unit is independent of the input unit. This rolling offset metric calculator example: 300 mm offset with 400 mm advance at 45 degrees gives true offset 500.00 mm and travel 707.1068 mm (707.11 mm). Imperial results also show the nearest 16th: 21.21 in displays as 21 3/16", and 7.84 in as 7 13/16". That makes this rolling offset calculator with fractions practical on site with a tape measure.

The true offset is the straight-line diagonal across the rolled plane: T = sqrt(offset^2 + advance^2). Travel is the longer pipe length between fitting centers: travel = T x cosecant(fitting angle), always bigger than T. Example: 12 in offset with 9 in advance gives true offset 15.00 in but travel 21.21 in at 45 degrees. A true offset calculator plumbing check that stops at T is only half the answer; the pipe you order and cut is the travel. In a rolling offset vs simple offset comparison, the simple (flat) offset uses depth x multiplier directly, while the rolling offset first combines two perpendicular dimensions into T.

Learning how to bend a rolling offset comes down to marks and shrink. (1) Measure the obstruction: say a 4 in deep offset with 30 degree bends. (2) Multiply depth by the cosecant multiplier: 4 x 2.00 = 8.00 in between bend marks. (3) Correct for shrink: the run shortens by 4 x 0.2679 = 1.0718 in, so move your first mark forward by about 1.07 in (field shortcut: 1.00 in). (4) Bend 30 degrees at each mark in opposite directions. The conduit bend shrink calculator tab on this page does steps 2 and 3 for any angle from 10 to 60 degrees, with both the exact and the field rule-of-thumb shrink values.