--- title: Rafter & Truss Calculator | Rafter Length Estimator description: Use our free Rafter & Truss Calculator to calculate rafter lengths from rise and run measurements. Perfect for roofing, framing, and truss planning. image: https://ls-usa.com/hubfs/Roofing-Pitch-Calculator.png --- [![LS Building Products](https://ls-usa.com/hs-fs/hubfs/Logo%20(13).png?width=98&height=67&name=Logo%20(13).png) ](https://ls-usa.com/) [ Get A Quote ](https://ls-usa.com/contact) ![Open](https://ls-usa.com/hs-fs/hubfs/Shape%201%20(4).png?width=31&height=26&name=Shape%201%20(4).png) ![close](https://ls-usa.com/hs-fs/hubfs/close-circle-fill.png?width=28&height=28&name=close-circle-fill.png) [ Get A Quote ](https://ls-usa.com/contact) ![LS Building Products ](https://ls-usa.com/hubfs/BG%20image.webp) ![LS Building Products ](https://ls-usa.com/hubfs/BG%20image.webp) # Rafter & Truss Calculator Easily calculate the correct rafter length for your roofing project with our Rafter & Truss Calculator. Simply input the rise and run (half-span) measurements to determine the accurate length of your rafters, ensuring a precise fit for your roof structure. [![Explore Lumber & Trusses](https://no-cache.hubspot.com/cta/default/22146047/204a1948-806c-4c71-a9b5-47fae78e77bf.png)](https://cta-redirect.hubspot.com/cta/redirect/22146047/204a1948-806c-4c71-a9b5-47fae78e77bf)   --- ## Rafter & Truss Calculator ### Choose Calculation Rafter Length Truss Count ### Rafter Length #### Calculation Basis Rise & Run Pitch & Run #### Rise ft ft in m cm #### Run (½ span) ft ft in m cm #### Rafter Length ft ft in m cm ### Truss Count #### Roof Length ft ft in m cm #### On-center Spacing in in ft m cm #### Number of Trusses   Share Result Reload Calculator Clear All Fields --- *This calculator is for general informational purposes only. Please verify all results with a licensed contractor, as actual project requirements may vary.* ## **Key Features** **✔ Clean, intuitive interface** for quick and easy input of rise and run measurements.** ✔ Real-time rafter length calculation** using the Pythagorean theorem.** ✔ Flexible calculation basis **lets you choose between rise & run or roof pitch.** ✔ Auto-converts between feet and inches **for greater measurement accuracy.** ✔ Instant result sharing **for contractors, builders, or estimators.** ✔ Fully responsive design**—works smoothly on mobile, tablet, and desktop. ## **How to Use It** 1. **Calculate Rafter Length:** Input your roof’s rise (vertical height) and run (horizontal span), and the calculator instantly computes the rafter length based on your inputs—no need for manual math or construction calculators. 2. **Choose Your Method:** Select your preferred calculation basis: either enter rise and run or switch to a different method like pitch-based inputs. The calculator adjusts automatically, giving you accurate results however you build. 3. **Precision Made Simple:** Get the precise rafter length you need to plan for cuts, material orders, or project estimates—ideal for trusses, rafters, and framing work. 4. **Built for Professionals & DIYers:** Whether you're a seasoned contractor or a homeowner planning a shed or roof extension, this tool helps eliminate guesswork and ensures correct measurements from the start. --- ## Build with Confidence Our [Rafter & Truss](https://ls-usa.com/products/trusses-framing-lumber-engineered-wood/) Calculator helps streamline planning and reduce errors, making it easier to source materials and stay on budget. It’s a must-have tool for any roofing or framing project—big or small. Start building smarter with the LS Rafter & Truss Calculator today. ### Questions about any of our products? We're ready to help you find a solution! 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