4 Online Gambrel Roof Framing Calculator Free Websites

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Here is a list of 4 free online Gambrel roof framing calculator websites. A gambrel roof is a two-sided roof which includes two slopes. Using these sites, you will be able to check dimensions for roof rafters, sweep angle, upper rafter and lower rafter angles, rafter length, roof area, and other details related to gambrel roof.

Based on the gambrel roof framing calculator website you’re using, you can enter input details like wall width, rafter thickness, rafter width, building length, house wall height, gable overhang, lower slope length, etc., and then you can calculate the result. Some of these sites also provide sample diagram and output diagram to understand well about the output and gambrel roof framing calculation.

Let’s check these free online gambrel roof framing calculator websites one by one.


Blocklayer Gambrel Roof Framing

Blocklayer brings a good gambrel roof framing geometry calculator. You can access that calculator using this link. The unique feature is it brings an animated diagram option. When you will set sweep angle and scale for the roof using the available sliders, it will change the diagram accordingly and you will be able to see the animation.

To calculate gambrel roof frame structure, you can provide input details like sweep angle, wall width, purlin thickness, rafter depth, ridge thick, overhang, gussets, etc. Once it is done, you can get the output diagram that will show dimensions (in feet or inches) for gambrel roof structure. Lower rafter and upper rafter angles and dimensions are also visible in separate diagrams.

Gambrel Roof Calculator

Gambrel Roof Calculator

Gambrel Roof Calculator (Homepage) is another good website on this list. It gives a lot of options to fill as input details. You can set roof width, height, overhang length, roof length, rafter thickness, roof verge distance, roof boarding thickness, sheet overlap, rafter spacing, roof boarding width, and other details or dimensions in inch. After that, it will show the output details. A diagram is also generated which makes it more useful.

The output will show:

  • Initial data or input details.
  • Roof size: which includes roof area, roof coating length, and one slope roof coating width.
  • Material estimate: in which you will see rafter length, rafters volume, rafters amount, material needed for main roof (tile, metal, slate, and other materials), and more.

It also lets you save all these details as PDF file to PC. The PDF file will contain watermark, but that won’t be a problem for personal use.



Spikevm is a handy option to calculate square footage of a gambrel roof. Its link is here. It provides a sample diagram upper pitch, lower pitch, and other parts of a gambrel roof to understand the basics. You can take some time to view that diagram or start the calculation.

You can add:

  • Building length (in ft and inches).
  • Gable overhang.
  • Lower roof pitch.
  • Upper roof pitch.
  • Eaves overhang.
  • Building width, etc.

When you use Calculate button, it will show the result. The output will contain lower roof angle, upper roof angle, root area in square feet, upper slope percentage, and lower slope percentage.


Kalk.pro website

Kalk.pro is a good competitor to other gambrel roof frame calculators covered on this list. It also displays gambrel roof diagram based on the input values. The unique feature is you can view diagram from different sides (top, frame from the hip, small rafters (left or right), frame from the side of the slope, etc.). The diagram can also be viewed in 3D mode which is another fantastic option not available in other gambrel roof framing calculators.

You can add input values which include:

  • House width, wall thickness, wall height, and wall length.
  • Roof height and overhang.
  • Type of roof: Soft or hard.
  • Map or diagram unit: cm, inch, m, etc.
  • Rafter washed down, rafter thickness, rafter width, etc.
  • Overlap side and overlapping above values.
  • Sheathing width and thickness.
  • Roofing sheets length and width.

Add the details and you will get calculation results, materials for construction (ridge beam, central/intermediate rafters, small timbers, sheathing, and more), etc.

We’ve also covered free baluster spacing calculators for you.

The Conclusion:

Here I close this list which has good online gambrel roof framing websites. All sites have a bit different options for input details to generate the output. So, you can try all these sites, and then check which will be more helpful to you.

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[Total: 10 Average: 3.1]

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