Roof Height Calculator With Pitch, Ridge, Rafter, and Area Results

Construction calculator

Project inputs

Version 2.0.0

Project name

Roof type

Calculation mode

Units and output precision

Input unit

Output unit

Decimal places

Construction rounding

Cost currency

Main roof dimensions

Building width

Use total wall-to-wall width.

Building length

Used for area and material estimates.

Horizontal roof run

Leave zero when width determines run.

Known roof rise

Wall or plate height

Eave height

Known ridge height

Known total building height

Known rafter length

Pitch, angle, and slope

Pitch rise

Pitch run

Roof angle in degrees

Angle in radians

Updated from degrees in the browser.

Slope percentage

Decimal slope

Gradient denominator

A value of four means 1 in 4.

Common pitch preset

Asymmetric and off-center roof options

These values apply to saltbox and unequal-pitch roofs.

Ridge offset from left wall

Left wall height

Right wall height

Left pitch rise

Left pitch run

Right pitch rise

Right pitch run

Gambrel and mansard segment options

Set lower and upper segment pitches for each half-span.

Outer segment run share

Outer segment run override

Inner segment run override

Lower pitch rise

Lower pitch run

Upper pitch rise

Upper pitch run

Construction adjustments

Include overhang Include heel height Include roof thickness

Eave overhang

Fascia depth

Truss heel height

Raised heel addition

Ridge-board thickness

Rafter depth

Roof assembly thickness

Ceiling height above plate

Floor-system thickness

Foundation height

Parapet height

Ground elevation datum

Finished floor elevation

Required attic clearance

Height-limit and reverse calculation

Maximum permitted height

Reverse solve

Material quantities and costs

Waste percentage

Sheet length

Sheet width

Bundle coverage in square feet

Underlayment roll coverage

Rafter spacing

Truss spacing

Ridge-cap length override

Area cost rate

Cost per sheet

Cost per bundle

Cost per truss

Project notes and browser options

Project notes

Enable live preview

Live geometry preview

Estimated rise—

Estimated ridge above base—

Estimated rafter—

Pitch and angle—

Results are geometric estimates. Structural design still requires professional review.

Multiple pitch comparison

Interactive

Compare six roof pitches using one building width and wall height.

Building width

Wall height

Building length

Pitches

Unit

Pitch	Angle	Roof rise	Ridge height	Rafter length	Approximate area

Roof pitch conversion table

Reference

Pitch	Angle	Slope	Rise per foot	Rafter multiplier	Rise across 24 ft width
0:12	0.00°	0.00%	0.00 in	1.0000	0.00 ft
1:12	4.76°	8.33%	1.00 in	1.0035	1.00 ft
2:12	9.46°	16.67%	2.00 in	1.0138	2.00 ft
3:12	14.04°	25.00%	3.00 in	1.0308	3.00 ft
4:12	18.43°	33.33%	4.00 in	1.0541	4.00 ft
5:12	22.62°	41.67%	5.00 in	1.0833	5.00 ft
6:12	26.57°	50.00%	6.00 in	1.1180	6.00 ft
7:12	30.26°	58.33%	7.00 in	1.1577	7.00 ft
8:12	33.69°	66.67%	8.00 in	1.2019	8.00 ft
9:12	36.87°	75.00%	9.00 in	1.2500	9.00 ft
10:12	39.81°	83.33%	10.00 in	1.3017	10.00 ft
11:12	42.51°	91.67%	11.00 in	1.3566	11.00 ft
12:12	45.00°	100.00%	12.00 in	1.4142	12.00 ft
13:12	47.29°	108.33%	13.00 in	1.4743	13.00 ft
14:12	49.40°	116.67%	14.00 in	1.5366	14.00 ft
15:12	51.34°	125.00%	15.00 in	1.6008	15.00 ft
16:12	53.13°	133.33%	16.00 in	1.6667	16.00 ft
17:12	54.78°	141.67%	17.00 in	1.7341	17.00 ft
18:12	56.31°	150.00%	18.00 in	1.8028	18.00 ft
19:12	57.72°	158.33%	19.00 in	1.8727	19.00 ft
20:12	59.04°	166.67%	20.00 in	1.9437	20.00 ft
21:12	60.26°	175.00%	21.00 in	2.0156	21.00 ft
22:12	61.39°	183.33%	22.00 in	2.0883	22.00 ft
23:12	62.45°	191.67%	23.00 in	2.1619	23.00 ft
24:12	63.43°	200.00%	24.00 in	2.2361	24.00 ft

Saved calculation history

No saved calculations yet.

Formula used

Centered gable run = building width ÷ 2
Roof rise = horizontal run × (pitch rise ÷ pitch run)
Roof rise = horizontal run × tan(roof angle)
Roof rise = horizontal run × (slope percentage ÷ 100)
Rafter length = √(run² + rise²)
Ridge height = wall height + heel height + roof rise
Total height = base elevation + ridge height + roof thickness
Rafter multiplier = √(1 + decimal slope²)
Roof area ≈ sloped roof length × building length × roof-side count

How to use this calculator

Choose the roof geometry

Select the roof type before entering dimensions. A gable roof uses half the building width. A shed roof normally uses the entire width. Saltbox roofs can use an off-center ridge. Gambrel roofs use two sloped segments per side.

Select a calculation mode

Choose the measurements already known for your project. Width and pitch is the most common mode. Run and angle is useful for field measurements. Known heights can recover pitch from existing buildings.

Enter consistent dimensions

Use one input unit for every length. Feet and inches accept mixed fractions. Enter 12 ft 7 1/2 in directly. Decimal feet also work for survey data.

Review construction adjustments

Add heel height when trusses sit above plates. Include roof thickness for finished ridge elevation. Enter ridge-board thickness for rafter shortening. Overhang adds sloped length beyond the wall.

Check the height limit

Enter the maximum permitted building height. The result shows remaining vertical margin. A negative margin means the design exceeds that limit.

Estimate roof materials

Building length drives roof area and framing counts. Waste increases purchase quantities for cuts and damage. Coverage settings can match local products. Cost settings provide a rough project allowance.

Compare alternate pitches

Use the comparison table below the calculator. Enter several pitch rises separated by commas. The table compares rise, ridge height, rafters, and area.

Export and document results

Download CSV data for spreadsheets. Download PDF reports for project records. Export the diagram as SVG or PNG. Save useful calculations inside your browser.

Important construction note

This calculator provides geometric estimates only. Loads and connections need separate engineering. Codes can define different height measurement points. Roofing manufacturers also publish minimum slope requirements. Always confirm final dimensions with qualified local construction professionals.

Frequently asked questions

What is roof height?

Roof height usually means vertical rise above the wall plate. Total building height includes walls, floors, foundations, and roof thickness.

Is roof run half the building width?

Yes, for a centered symmetrical gable roof. Shed roofs use the full horizontal width. Off-center roofs use separate side runs.

How does a 6:12 pitch work?

A 6:12 pitch rises six units for every twelve horizontal units. Its decimal slope equals 0.5.

Does overhang change ridge height?

Normally, overhang changes rafter length but not ridge height. Raised heels and wall geometry can alter that relationship.

Can feet and inches include fractions?

Yes. Entries like 12 ft 7 1/2 in are accepted. Decimal inches are also supported.

Are material estimates exact?

No. They use geometry, spacing, coverage, and waste assumptions. Valleys, hips, openings, and product rules can increase quantities.

How is a height limit checked?

The calculator compares calculated total height against your entered maximum. It reports the remaining margin or excess height.

Can this replace structural engineering?

No. It does not size members or verify loads. A qualified professional should review structural design and local code compliance.

Example data table

Roof	Width	Pitch	Wall height	Calculated rise	Calculated ridge
Gable	24 ft	6:12	9 ft	6 ft	15 ft before heel
Gable	30 ft	8:12	10 ft	10 ft	20 ft before heel
Shed	18 ft	3:12	9 ft	4.5 ft	13.5 ft before heel
Flat drainage	40 ft	1:48	12 ft	0.83 ft	12.83 ft