Dado Blade Shim Calculator

Dado Blade Shim Calculator

Fine-tuning a stacked dado blade set? This calculator tells you exactly how many shims to add for your target width.

Additional Width Needed = Target Dado Width - Base Blade Set Width
Number of Shims = round(Additional Width / Shim Thickness)

Example

Targeting a 0.75-inch dado, base blade set already at 0.75 inches:

0 shims needed

Why Shims Exist at All

Stacked dado blade sets use thin metal shims placed between the chippers to fine-tune the final cut width beyond what the base blade combination alone provides - this lets a single dado set produce a range of widths rather than only the fixed widths of the blades themselves.

Always Cut a Test Dado First

Always cutting a test dado in scrap wood matching the actual project material, and checking the fit before cutting the final workpiece, is standard practice - actual material thickness commonly varies slightly from nominal sizing (a "3/4 inch" plywood sheet is often somewhat thinner), which this calculation alone can't account for.