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Bevel Angle Calculator

Calculate the precise bevel angle for planking, frames, and other angled joints.

Quick Samples
Try these common configurations to get started

Hull Side to Bottom

A typical chine joint

Cabin Side to Deck

A common cabin joint

Bulkhead to Hull

A bulkhead landing on the hull

Hull Dimensions
Enter your boat's principal dimensions

Angle between joining surfaces (degrees)

e.g., inches, mm

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About This Tool
The Bevel Angle Calculator is a critical tool for ensuring tight, fair joints in boat construction. When two panels or planks meet at an angle (like the side of the hull meeting the bottom), their edges must be beveled to fit together perfectly. This calculator determines the precise angle for that bevel based on the angle of the hull joint. It also provides the 'Saw Setting Angle', which is the practical angle you need to set on your table saw or circular saw to achieve the cut.

Key Concepts:

Bevel Angle: The angle cut into the edge of a material to allow a tight joint with another piece.
Hull Angle: The angle between two joining surfaces, like the hull side and bottom.
Saw Setting Angle: The angle to set on your saw, measured from a square 90-degree cut.
Fair Joint: A joint that is smooth and aligns perfectly with the surrounding surfaces.
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Bevel Angle Calculator Calculator: What It Does and Why It Matters

When planks, panels or sides meet at an angle rather than flat, the joining edges must be bevelled so the faces close tight and the seam can be glued, taped or fastened properly. Get the bevel wrong and the joint gaps at the surface while touching at the root, the most frustrating fault in plank-on-frame and polygonal hull work.

The calculator takes the included angle the two faces form at the corner and returns the bevel to cut and the saw setting that produces it. A very acute result is a feather edge, thin as paper at the tip and impossible to keep from crumbling, so the tool flags those corners as a warning to rethink the joint.

Enter the hull or joint angle and the material thickness, and the calculator gives the bevel angle, the table-saw or planer setting, and a caution when the geometry produces an unworkably fragile edge.

The Bevel Angle Calculator Formula
Bevel Angle = 180° − Included Angle; Saw Setting = 90° − Bevel Angle; A bevel under about 5° is a fragile feather edge
  • Included Angle — The angle the two faces form at the corner being joined
  • Bevel Angle — The slope to cut on the mating edge so the faces close
  • Saw Setting — The blade tilt off vertical that cuts that bevel
  • Thickness — The depth of the material being bevelled
  • Feather Edge — A very acute bevel whose thin tip is weak and hard to cut
Worked Example: Bevel Angle Calculator Step by Step
  1. 1Two plank sides meet at a hard chine forming an included angle of 120 degrees.
  2. 2Bevel angle = 180 − 120 = 60 degrees off the reference, an open, easy bevel.
  3. 3Saw setting = 90 − 60 = 30 degrees of blade tilt from vertical.
  4. 4Because the bevel is well above five degrees the cut edge has real thickness behind it and will not feather, so a glued and taped seam holds soundly.
  5. 5Had the corner instead produced a bevel of only three degrees, the tool would warn that the thin edge crushes under clamp pressure and the joint design should change.
How to Use This Calculator
  1. Measure the angle the two faces form at the joint.
  2. Enter the thickness of the material you are bevelling.
  3. Read the bevel angle to cut on the mating edge.
  4. Set the saw tilt to the reported setting off vertical.
  5. Heed the feather-edge warning if the bevel turns out very acute.
Bevel Angle Calculator Reference Table
Bevel AngleCharacterGuidance
Under 5°Feather edgeRedesign joint; will crumble
5° - 15°Narrow bevelCut carefully, clamp gently
15° - 45°Standard bevelGlue and tape normally
Over 45°Open bevelEasy to cut and fasten

Bevel ranges and how they behave.

What This Means in a Real Build
  • Cut the bevel slightly proud and fair it to the line, because a hard chine or box section closes only when both mating edges are exactly complementary, and removing a little at a time with a block plane lets the seam draw tight without leaving a visible gap at the face.
  • Test on an offcut at the same thickness. A bevel that reads right on the calculator can still behave differently once the material's thickness is folded into the corner geometry, so dry-fit two scrap pieces bevelled to the number before cutting the real plank.
  • Mind the reference face. The bevel angle and the saw setting are complements, so a table saw tilted thirty degrees off vertical cuts the same joint a guide set to sixty off horizontal does; knowing which your tool reads prevents cutting the mirror-image bevel that will not close.
  • Thicker material forgives more. The same included angle yields a stronger root when the stock is heavier, so where a feather edge threatens, a thicker plank or a backing cleat gives the thin side something solid to bear on instead of crushing.
  • Back a fragile corner with structure. Where the geometry truly demands an acute bevel, add interior battens or a glued fillet behind the seam so the fragile edge is supported and the load path runs through sound material rather than the paper-thin tip.

Formula verified against standard naval-architecture references · Updated October 2026

Bevel Angle Calculator Calculator: Frequently Asked Questions

How do I work out a bevel angle for planks?

Take the angle the two plank faces form at the corner and subtract it from 180 degrees to get the bevel to cut; the saw tilt is that bevel measured off vertical. A chine where sides meet at 120 degrees needs a 60 degree bevel, which a saw set 30 degrees off vertical produces. The calculator does both conversions so you can translate straight to a tool setting.

What is a feather edge?

It is the razor-thin lip a very acute bevel leaves at the top of a joint, where the two nearly parallel faces taper to almost nothing. Under roughly five degrees that edge crushes under a clamp, tears when demoulding and gives glue no thickness to grip, so the calculator warns you the joint will be fragile and should be redesigned or backed.

What saw setting gives the bevel?

Subtract the bevel angle from 90 degrees, because a blade tilts from vertical while the bevel is measured from the face. A 60 degree bevel needs a 30 degree blade tilt; a 20 degree bevel needs 70 degrees of tilt. The calculator reports both so you match whichever scale your saw uses.

Why does my bevelled seam gap at the top?

Usually the two edges are not exactly complementary, or one was cut referencing the wrong face, so they touch at the root but part at the surface. Re-measure the included angle, confirm both mates use the same bevel, and fair one edge with a plane until the seam closes along its full depth.

Does material thickness matter?

Yes. The same included angle produces a weaker, thinner edge in light stock than in heavy stock, because the bevel's root depth scales with thickness. Where a marginal bevel is unavoidable, a thicker plate or an added backing member turns a fragile feather into a joint that can actually be clamped and glued.

Can I use this for a box or cabin side?

Certainly. Any time flat panels meet at a non-right angle, a corner bench, cabin side to shear, or a polygonal tank, the mating edges need the bevel this tool computes. Enter the corner angle the panels form and cut both to the reported bevel so the assembly closes square and clean.

Related Boat Building Tools
Sources & Further Reading
  • Boatbuilding — Howard I. Chapelle
  • The Backyard Boatbuilder — Daniel St. John Green
  • Gougeon Brothers on Boat Construction — Gougeon Brothers