Feb 19, 2026 · The 3-4-5 rule is a handy and foolproof way to determine if a corner is perfectly square when doing carpentry or other DIY projects, from building a deck to laying tile.

Jun 15, 2021 · Each number represents a length of a side of a right triangle. When the sides measure up accordingly, you'll have a perfect 90-degree angle. It's important to note that the 3-4-5 values can …

Apr 14, 2020 · Learn how to square a corner using the 3-4-5 method (or the 3-4-5 rule). This technique ensures perfect right angles for any paver project.

Use our free 3-4-5 Rule Calculator to quickly check or create perfect right angles for construction, framing, decks, and pergolas. Accurate and easy to use.

Carpenters and builders often use the 3-4-5 method for squaring corners and ensure that the projects they are building have a precise 90-degree angle. In the residential and construction world …

To create corners, we use the 3-4-5 rule derived from the Pythagorean theorem of basic geometry: A 2 + B 2 = C 2. This means the square of the hypotenuse of a right triangle is equal to the sum of the …

Mar 20, 2026 · Learn how to use the 3-4-5 rule to mark out a perfectly square layout on the ground using just stakes, string, and a tape measure.

Jan 11, 2026 · The 3-4-5 rule in carpentry is a method used for creating precise angles and square layouts in construction projects. It involves the use of a triangle with sides measuring 3 feet, 4 feet, …

Jan 13, 2026 · Calculate 3-4-5 rule measurements from one side length, or find a missing right triangle side plus scale factor, perimeter, and area.

Oct 4, 2025 · Learn how to use the 3-4-5 rule to achieve perfect 90° angles in your foundation layout. A simple and accurate site method every engineer and builder should know.