# Rafter Calculator

> Calculate rafter length, roof rise, and pitch angles for residential roof framing structures.

**URL:** https://www.calculatoranswers.com/rafter-calculator
**Category:** Home

## Quick Answer

Estimate roof rafter dimensions. Enter the building width, roof pitch, and overhang to calculate total rafter length, vertical rise, and pitch angle.

## Definition

A rafter calculator is a carpentry construction tool used to determine the dimensions of roof framing members. Based on the geometry of a gable roof, it treats the horizontal half-span (including any overhang) and the vertical rise as the two perpendicular sides of a right triangle. The calculator applies the Pythagorean theorem to determine the precise diagonal length of the rafter board. It also calculates the vertical rise from the wall plate to the ridge and converts the pitch into an exact angle in degrees. Carpenters and builders use this calculator to estimate lumber quantities and mark cuts.

## How to Use

1. **Enter building width** — Type the total width of the building in feet and inches.
2. **Select roof pitch** — Choose a standard roof pitch from the dropdown or enter a custom rise.
3. **Input overhang length** — Enter the desired rafter overhang distance in inches.
4. **Review framing outputs** — Read the calculated rafter length, total rise, and pitch angle.

## Disclaimer

This calculator provides estimates for educational and planning purposes. Always consult a qualified professional for specific advice on financial, medical, legal, or other regulated decisions.

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