Pie Cut Calculator
Custom made pie cut tubing
How it works
Calculating pie cut bends
This pie cut bend/angle calculator helps you design precise segmented bends for exhausts, intercooler piping, headers, and custom fabrication projects.
It calculates the slice angle, cut angle, spacing, and segment widths needed to build a smooth and accurate 90° bend from individual pie cuts. Because each segment contributes a fixed amount of bend, you can easily create larger or smaller angles by adding or removing pieces – no need for a separate “total bend angle” input.
The tool also accounts for the difference between long and short sides of each segment and works seamlessly in both millimeters and inches.
How to use
Select unit system (mm or inch)
This calculator supports both millimeter and inches. Simply use the dropdown to select your preferred unit of measurements
Tube outer diameter
Enter the outside diameter of your tube.
Desired bend radius
Select how “tight” or “loose” you want your bend to be. Here you can either use the dropdown menu or enter a free value in the input field. If the dropdown is used the input field will auto populate (but it’s infinitely adjustable). The default values are 0,75x, 1,0x, 1,5x and 2,0x your tube diameter.
Number of pie cuts
Select how many pie cuts you want each 90 degree to have. A rule of thumb is that the higher number you enter here, the smoother the bend will be.
End pieces vs mid pieces
End pieces vs mid pieces
A typical pie cut bend uses two end pieces and several mid pieces. Mid pieces have two angled cuts; end pieces usually have one straight cut and one angled cut. The calculator doesn’t need special settings for this – you just use the same cut angle for the angled side and choose which end you leave straight to butt against a straight tube.
How to interpret the results
Slice angle per segment
This is how many degrees of bend each individual pie-cut segment contributes. A 90° bend is just multiple segments added together. For example, if the slice angle is 15°, then 6 pieces give you 90°, 8 pieces give you 120°, 3 pieces give you 45°, and 12 pieces give you 180°. You don’t need to enter total bend angle into the calculator – you simply use more or fewer segments.
Saw cut angle (each end)
This is the angle you set on the saw for the miter cuts. Two equal miter cuts form one segment, so the cut angle is always half the slice angle. For the mid-pieces in a bend, both ends are cut at this angle. For end pieces, you usually do one straight cut (0°) and one angled cut – the angled side still uses the same cut angle from the calculator.
Cut spacing along centerline
This is the distance between cut locations measured along the tube’s centerline. It’s useful when you’re laying out all the cuts on a straight length of tube before heading to the saw. Cut spacing does not change if you make a longer or shorter final bend; you just add or remove segments.
Long side width (outer edge) & short side width (inner edge)
These give you the chord length on the outside and inside of the bend for each segment. In practice, they’re most helpful when you want to double-check that your cut geometry is symmetrical and consistent, or when you’re marking and trimming pieces for tight, repeatable fit-up.
Pie Cut Calculator
Bend radius is measured at the tube centerline.
Results:
Enter your values to calculate.
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