How long of a 2x12 do I need for stairs: Understanding the length requirements for 2x12s in stair constructionEvelyn WrenSep 02, 2025Table of ContentsTips 1:FAQTable of ContentsTips 1FAQFree Smart Home PlannerAI-Powered smart home design software 2025Home Design for FreeWhen it comes to building stairs, one of the most critical components is the stringer, which is the support that holds the treads and risers in place. The length of a 2x12 stringer you need for your stairs will depend on several factors, including the total rise (the vertical distance from the lower floor to the upper floor), the desired run (the horizontal distance the stairs will cover), and the angle of the stairs. Generally, a standard stair rise is around 7 inches, and the run is about 10 inches, although these can vary based on building codes and personal preference. To determine the length of the stringer, you can use the Pythagorean theorem, where the total rise becomes one side of a right triangle, the total run becomes the other side, and the stringer length is the hypotenuse. For instance, if your total rise is 10 feet (120 inches) and your total run is 12 feet (144 inches), you would calculate the length of the stringer as follows: square the rise (120^2 = 14400), square the run (144^2 = 20736), and then add those two numbers together (14400 + 20736 = 35136). Finally, take the square root of that sum (√35136 ≈ 187.7 inches). This means you would need a 2x12 that is at least 15.6 feet long to cut your stringers. Keep in mind that you should also account for waste and any additional cuts you may need to make for the notches where the treads and risers will sit. Therefore, it is often wise to purchase a bit more material than the calculated length, especially if you're a beginner and may make mistakes. Additionally, if you're building a staircase that has landings or turns, the calculations will become more complex, and you might need to consult a professional or use stair design software to ensure accuracy. Remember to always check local building codes before beginning your project, as they may have specific requirements for stair dimensions and materials. Using quality materials and following safety guidelines will ensure that your stairs are both functional and reliable in the long term. Always wear appropriate safety gear when working with power tools and heavy materials. By understanding these principles, you can confidently determine how long of a 2x12 you need for your stairs and take on this DIY project with ease!Tips 1:Make sure to double-check the measurements before cutting to avoid wasting materials.FAQwelcome to CoohomHome Design for FreePlease check with customer service before testing new feature.