The 3-4-5 Rule Calculator is designed to calculate the hypotenuse or other sides of a right triangle based on given side lengths, following the 3-4-5 rule. In the Basic Calculator, you can enter values for Side A and Side B to find the Hypotenuse. Alternatively, leave one side blank to solve for that side using the Pythagorean theorem.

For a more complex calculation, switch to the Advanced Calculator mode, where you can input Angle between Side A and B, along with lengths of Side A and Side B, to compute the Hypotenuse based on the angle. Simply click Calculate to view the result or Reset to clear all fields.

### Input Field Definitions

Input Field |
Purpose |

Length of Side A (units) |
Enter the length of side A to calculate the hypotenuse or other sides in a right triangle. |

Length of Side B (units) |
Specify the length of side B for the calculation. |

Length of Hypotenuse (units) |
Displays the calculated hypotenuse length based on sides A and B. Leave blank to auto-calculate. |

Angle between Side A and B (degrees) |
Input the angle between sides A and B for advanced calculations. |

Length of Side A (units) (Advanced) |
Enter the length of side A for advanced hypotenuse calculation. |

Length of Side B (units) (Advanced) |
Specify the length of side B in the advanced calculator. |

Length of Hypotenuse (units) (Advanced) |
Shows the calculated hypotenuse based on the entered angle and side lengths. |

### How To Calculate

**Example 1 – Basic Calculation**

Step |
Calculation Process |

Step 1 |
Enter **Length of Side A** as 3 and **Length of Side B** as 4. |

Step 2 |
Leave **Length of Hypotenuse** blank. |

**Result** |
The calculator displays **Length of Hypotenuse** as 5, following the 3-4-5 rule. |

**Example 2 – Advanced Calculation**

Step |
Calculation Process |

Step 1 |
Enter **Angle between Side A and B** as 90 degrees, **Length of Side A** as 5, and **Length of Side B** as 12. |

**Result** |
The calculator shows the **Length of Hypotenuse** as approximately 13, using the angle and side lengths provided. |