Calculate roof ridge height from building span, wall height and roof pitch, or solve for the pitch, wall height or span needed for a target peak height.

The primary answer uses ideal roof-line geometry from the wall top. Framing and roof-plane elevations are separate estimates; verify structure, cuts, roof details and official height definitions independently.

For a shed roof, use the lower wall. Enter 0 to use the wall top as datum.

For 6/12, enter 6. Off-center geometry uses the left slope.

Framing and height comparison

Blank means no thickness deduction. Not used for a shed roof.

Blank omits rafter-depth/HAP framing offsets.

Blank means an unnotched zero-length seat. Enter the actual modeled cut, not a presumed wall width.

Thickness perpendicular to the roof plane. Blank means no added layer.

Blank means no overhang; affects rafter length, not peak elevation.

Blank skips comparison. Use the same datum; this is not a zoning-compliance determination.

Ridge Height Formula

The following formula gives an ideal centered-gable roof-line elevation from a shared datum, before rafter, seat, roofing and other finish offsets.

RH = H + (W / 2) × tan(A)

Variables:

  • RH is the ridge height
  • H is the height of the wall
  • W is the horizontal wall-to-wall span, excluding overhang
  • A is the pitch angle in degrees (or use slope = rise-per-12 / 12 = slope-percent / 100)

For a centered gable, use half the span as the horizontal run, multiply by tan(A), then add wall-top elevation. A shed uses the full span; an off-center gable uses the entered left run and assumes equal wall elevations. The target-based solve modes use this same ideal geometry. Framing-face and modeled upper roof-plane elevations are separate outputs: thickness is measured normal to the roof plane, and the height comparison recomputes offsets as pitch changes. Off-center framing estimates describe only the entered left slope.

What is a Ridge Height?

Ridge height is a roof elevation measured from a specified datum. This calculator distinguishes an ideal roof-line peak, a rafter-top elevation at the near ridge face, and an extrapolated upper roof plane. Caps, vents, truss heels, structural adequacy and official zoning height definitions need separate checks; the calculator does not establish compliance or an acceptable notch or ridge-member size.

How to Calculate Ridge Height?

The following steps outline how to calculate the Ridge Height using the given formula:

  1. First, determine the height of the wall (H).
  2. Next, determine the width of the building (W).
  3. Next, determine the pitch angle of the roof (A).
  4. Next, substitute the values of H, W, and A into the formula: RH = H + (W / 2) * tan(A).
  5. Finally, calculate the Ridge Height (RH).
  6. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge:

Height of the wall (H) = 10 ft

Width of the building (W) = 30 ft

Pitch angle of the roof (A) = 30 degrees. For this centered gable, RH = 10 + 15 × tan(30°) ≈ 18.6603 ft before framing and finish offsets.