Example 1
- Span: 8 m
- Angle: 35°
- Wall height: 2.8 m
Ridge height: 5.60 m
This shows how a medium roof angle can significantly increase the total building height.
Ridge height calculator
Type building span and roof pitch. The calculator uses half the span, multiplies by tan of the angle, and adds the walls. An 8 m roof at 35° with a 2.8 m wall is a 5.60 m ridge. At 10 m, 40°, and a 3.0 m wall you get 7.20 m. A narrower 7.2 m at 30° and 2.6 m is 4.68 m.
Quick way to compare roof options for building form and attic space - not a structural design. Related: roof pitch angle, slope percent.
Results
Span / building width (m), Roof pitch (°) and Wall height to eaves (optional, m). The result shows up here.
How the results are calculated
Ridge height joins half the span, the pitch, and the walls. The formula is (span divided by 2) times tan(pitch) plus wall height to the eaves. The chart shows how the ridge grows with pitch at your span. Type the angle in degrees, not as a slope percent.
An 8 m wide house, a 35° roof, and a 2.8 m wall give 5.60 m from floor to ridge. A wider 10 m at 40° and a 3.0 m wall is 7.20 m, a clearly taller attic. A narrower 7.2 m at 30° and 2.6 m stays at 4.68 m. The roof rise alone at 8 m and 35° is 2.80 m; the rest is the wall.
Type span or building width in the header unit and pitch in degrees. Wall height to the eaves is optional; empty leaves the roof rise alone. A comma in 7.2 works like 7,2.
Angle from rise and half-span lives on roof pitch: 2.8 m on 4.0 m is 34.99° and 70%. A 0.6 on 6 m slope is 10%, another scale. 3-4-5 does not supply a ridge.
A 45° pitch on an 8 m span gives 4 m of rise, because tan(45°)=1. An empty wall leaves those 4 m as the ridge above the eaves. Typing 35 as span instead of pitch breaks the scale: a 35 m building is a different roof.
Type 8, 35, and 2.8, click Calculate, and match 5.60 m. Then 10, 40, and 3.0: 7.20 m.
How to use this calculator
- Type span or building width in the header unit, for example 8.
- Enter roof pitch in degrees, for example 35. That is not a slope percent.
- Optionally add wall height to the eaves, for example 2.8 m.
- Click Calculate. 8 m, 35°, and 2.8 m give 5.60 m. 10 m, 40°, and 3.0 m give 7.20 m.
- Angle from rise belongs on the roof pitch page. This calculator stays ridge height.
tan 35° and a 5.60 m ridge
Half the span times tan of the pitch, plus the walls. An 8 m roof at 35° with a 2.8 m wall is a 5.60 m ridge.
- tan
- Tangent of the roof pitch. (8/2) × tan(35°) + 2.8 ≈ 5.60 m. At 10 m, 40°, and a 3.0 m wall you get 7.20 m.
- °
- Pitch from the second field. 35° on an 8 m span is that 5.60 m. 30° on 7.2 m and a 2.6 m wall is 4.68 m.
Example scenarios
Example 2
- Span: 10 m
- Angle: 40°
- Wall height: 3.0 m
Ridge height: 7.20 m
With both larger span and steeper pitch, ridge height grows quickly, which makes this calculator useful even at concept stage.
Example 3
- Span: 7.2 m
- Angle: 30°
- Wall height: 2.6 m
Ridge height: 4.68 m
This is a good example of how a gentler roof clearly lowers the final building form.
Related calculators
FAQ
What ridge at 8 m, 35°, and a 2.8 m wall?
5.60 m. Half-span 4 m times tan(35°) ≈ 2.80, plus 2.8.
What ridge at 10 m, 40°, and a 3.0 m wall?
7.20 m. A steeper pitch and a wider building, a taller attic.
What ridge at 7.2 m, 30°, and 2.6 m?
4.68 m. A narrower house and a gentler 30° roof than the 8 m / 35° sketch.
Is 35 the same as a 35% slope?
No. The field is degrees. A 35% slope is about 19.3°, which you count on slope percent.
What if walls are empty?
You keep the roof rise alone. At 8 m and 35° that is about 2.80 m above the eaves.
Where do I get a 35° pitch?
From the drawing, or from roof pitch: 2.8 m rise and 4.0 m half-span give 34.99°.
How much rise at 45° and an 8 m span?
4 m, because tan(45°)=1 and half-span is 4. The wall adds on top.
Does 3-4-5 replace the ridge?
3-4-5 checks a right angle in plan. Here the tangent of roof pitch goes in.
Does the chart change 5.60 m?
The chart shows other pitches at the same span. The calculator result stays with the pitch you typed.
How do I handle an uneven gable?
The calculator uses one span and one pitch. Count two different slopes separately and compare.
Knowledge sources
Volume and waste come from the sizes you type. Below are volume and NIST SI units.
Page updated in 2026.