How to Use This Compound Angle Calculator
This free compound angle calculator takes the guesswork out of setting up your table saw for angled cuts. Whether you're building a tapered planter box, a decorative catchall bowl, or a segmented turning blank, you'll get the exact blade tilt and miter sled settings for your project—displayed in both saw scale format and digital gauge readings.
What Are Compound Angles?
A compound angle cut combines two angles simultaneously: the blade tilt (bevel) and the miter angle. While simple cuts only use one angle at a time, compound cuts are necessary when building shapes where side panels both lean outward AND meet at angles other than 90 degrees. The math behind these cuts involves trigonometry that most woodworkers would rather avoid—which is exactly why this calculator exists.
Common Projects That Require Compound Angles
Tapered Planters: Garden planters with side panels that slope outward create a classic look while providing excellent drainage. Whether you're building a four-sided rectangular planter or a hexagonal cedar planter, compound angles ensure tight joints where the tapered side panels meet.
Decorative Boxes and Bowls: Catchall bowls, pencil holders, and decorative vessels often feature side panels that taper gently from base to rim. These projects require precise compound angles for seamless grain matching at the joints.
Segmented Turning Blanks: Woodturners use compound-cut segments to create multi-sided blanks for lathe work. The calculator's n-sided box settings work perfectly for building segmented rings that stack into bowls or vases.
Speaker Enclosures: Custom speaker cabinets with tapered sides require compound angles for structural integrity and acoustic performance. The rectangular frustum calculator handles these non-symmetric designs.
Understanding Your Table Saw's Angle Readings
One source of confusion for woodworkers is the difference between the angles displayed on your table saw's built-in scale versus what a digital angle gauge shows. Your table saw's blade tilt scale reads 0 degrees when the blade is perfectly vertical. A digital angle gauge placed against the blade reads 90 degrees in that same position. This calculator provides both readings, so you can use whichever method you prefer for setting up your table saw.
Three Ways to Describe Your Project
Different woodworkers approach their projects differently, so this calculator offers three input modes. If you're using a miter sled with fixed locking points, enter your miter sled angle to see what slope and blade tilt result. If you're designing from scratch, enter the side panel slope you want to achieve. Or if you're replicating a previous project and know the blade tilt you used before, enter that to calculate the matching miter angle.
Getting the Cut List Right
Beyond the angle settings, successful compound-angle projects require accurate dimensions. The calculator provides complete cut lists showing the top and bottom edge lengths of each side panel, accounting for the fact that tapered panels are longer at the top than the bottom. It also calculates the base plate dimensions with the correct bevel angle, ensuring your bottom drops in cleanly to meet the angled side panels.
Tips for Accurate Compound Cuts
Always test your settings on scrap wood before cutting your project pieces. Set your blade tilt first, then adjust your miter sled. For tapered boxes, place the inside face of the board down on the table. Cut all pieces with matching settings at once before adjusting for the next cut, and label each piece as you go. Finally, dry-fit your assembly before applying any glue to catch any measurement errors early.
When Standard Equipment Isn't Enough
This calculator will warn you when angles exceed the typical limits of table saw equipment. Most table saws tilt 0 to 45 degrees, and most miter sleds have preset stops at common angles. If your project requires steeper angles, you may need a compound miter saw with extended range, a custom jig, or a redesign of your project parameters. The calculator helps you identify these situations before you start cutting.
Available Calculators
This toolset includes ten specialized calculators for different woodworking scenarios:
- N-Sided Box: Build boxes, planters, and containers with any number of sides and tapered walls. Includes complete cut lists and base plate dimensions.
- N-Sided Pyramid: Calculate cutting angles for pyramid shapes with triangular faces meeting at an apex. Perfect for decorative post caps.
- Rectangular Pyramid: Pyramids with different X and Y base dimensions, useful for asymmetric architectural elements.
- Rectangular Frustum: Truncated pyramids with different top and bottom openings— ideal for speaker enclosures and tapered containers.
- Platonic Solids: Reference angles for the five perfect geometric solids: tetrahedron, cube, octahedron, dodecahedron, and icosahedron.
- Post & Board: Calculate angles where a sloped board meets a vertical post, common in deck railings and timber framing.
- General XYZ: The most flexible calculator—define any two surfaces using 3D normal vectors for complex geometric joints.
- General Angles: Specify how boards meet horizontally and how each tilts from horizontal to calculate cutting angles.
- Flip Board: Convert cutting angles when you need to flip the board on edge instead of laying it flat.
- Effective Kerf: Calculate the actual slot width when making compound cuts, accounting for blade tilt and miter angle.