Please note this is a beta tool.

The math couldn't very well be wrong...

This calculator is built for luthiers who want to rescale a guitar brace while keeping both stiffness (EI) and weight the same. In practice, that means you can swap materials or change the cross-section of a brace without losing the tonal balance you already know works.

It handles the common gabled brace shape: a rectangle with a triangular cap and lets you start from a “reference brace” with known dimensions, density, and either Young’s modulus or a measured tap-tone frequency. From there you enter the properties of your new material, and the tool calculates the new width and heights you’ll need to match mass and stiffness.

How to use:

1. Enter the reference brace dimensions (width, rectangle height, triangle height).
2. Enter its density, and either Young’s modulus or a measured frequency + length.
3. Enter the new material’s density, and again either E or a measured frequency.
4. Choose whether to keep the gable ratio the same.
5. Click Calculate to see the new dimensions that preserve stiffness and weight.

The output shows the new brace’s width, rectangle height, triangle height, total height, and the effective modulus values used for the calculations. You can use this as a design aid to compare spruce, redwood, carbon-reinforced stock, or any other brace material where stiffness-to-weight trade-offs matter.

Reference Brace (known good)

New Material

Options