If you're unsure about the terms, such as the on-center spacing, refer to the illustrations below: (Image created on the basis of: King post truss 3D created by George Ponderevo, licensed under the Creative Commons Attribution-Share Alike 3.0 Unported licence.) total costs = truss count × single truss price.total costs = truss count × single truss price + cost per time unit of work × duration of work.

To calculate the costs, we use the following two formulas: Rounded up to the closest integer (for example, if the result is 14.5, you need to get 15 trusses). To do so, it uses the following equations: If you're unsure about the terms such as roof run and rise, refer to the illustration below: (Image created on the basis of: King post truss 3D created by George Ponderevo, licensed under the Creative Commons Attribution-Share Alike 3.0 Unported licence.)Īs you know, figuring out rafter length and other truss dimensions is not the only thing you can use this tool for! Our roof truss calculator can also help out with planning out your roof project by estimating the truss count and showing you the costs you can expect for the materials and their installation. We can merge these two equations to get a single rafter length formula based on roof pitch: So what you need to do first is to get the pitch using the following formula: The one difference is that we need to calculate the roof rise using the pitch first. The formula used to calculate rafter length from roof pitch is, in fact, the same as the one above. For calculations based on the roof pitch:.For calculations based on the roof rise:.

What is more, the formula used to calculate roof truss dimensions is one you probably know very well - it's the exact same formula you use to describe a right triangle! Usually, that is either the pitch or the rise of the roof. It all comes down to what information you already have. This rafter length calculator lets you calculate roof truss dimensions using two slightly different sets of variables. We illustrated the variables you need to fill out in the calculator. As soon as you fill in all the variables, you will see the total expenses at the bottom of the calculator.ĭon't worry if you're unsure of what exactly is meant by such terms as the roof's run, rise, on-center spacing, etc. If you pick yes, you will also need to declare how much per time unit would the contractor installing the trusses charge you, as well as the expected duration of the installation. The roof truss calculator will return the total expenses in the bottom-most field. If you pick no, the only thing left to input is the cost of a single roof truss. In the next fields of the calculator, decide whether you want to include the costs of installation in the calculations.

Our tool can also figure out the approximate roof truss cost. Input the roof length, the on-center spacing (the distance between the middles of two neighboring roof trusses), and the roof truss calculator will return the number of roof trusses needed. You can input the roof pitch in any of the three formats (angle, percentage, ratio), and our tool will automatically tell you the other ones. You can input any of the two values to get the third one calculated. Here as well, our calculator works both ways. After doing that, you will see the rafter length in the bottom field. If you decided to include roof pitch in your calculations, to get the rafter length, you will need to input the run and the pitch of the roof. That is, you can also use it to calculate the rise or the run! If you already know the rafter length and want to figure out any of the other dimensions, simply input the two you know, and you will get the third one. Please note that the rafter length calculator works both ways. If you picked the rise, all you need to do is input its value, put in the roof's run, and the calculator will return the rafter length in the bottom-most field. If you want to learn more about the way it's calculated, check out our roof pitch calculator. You can choose the rise of the roof (which is its height), or the roof pitch (which is the slope created by the rafter). Start by deciding what you want your calculations to be based on. In the field above the illustration, pick either 'rafter length' or 'truss count'. To start your calculations, you need to choose from the two options mentioned above. You can use it either as a rafter length calculator, and get the dimensions of your trusses estimated or as a roof truss count calculator, which will also allow you to estimate the roof truss costs and even include the price of installation.

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