
Rafter Tools is an android app with functions to calculate complex roof framing angles that other roof framing calculators don't offer.
Calculating common rafters with a construction calculator is fairly easy, but to be a master carpenter you need more roof framing angle information then the construction calculators offers.
With the Rafter Tools android app you'll be able to calculate all of the complex angles for roof framing. As an American Carpenter & Builder I've written this roof framing calculator
as a roof framing geometry and trigonometry learning tool as well as a roof framing rafter calculator that can be used to build simple gable roofs to the most complex unequal pitched roofs with roof eave angles greater than 90°.
The Rafter Tools app has Quad Tetrahedra Analytic Algorithm Technology to help prevent unconstructable user input.
The Rafter Tools app has support for any roof eave angle from 30° to 180° as well as irregular hip roofs.
All of the roof framing functions are case studies from my book "Holy Grail of Roof Framing Geometry & Trigonometry" .
The app's main screen uses a left swipe motion to display all of the different calculators.

Calculations in Metric or Imperial Units or Base 10
Imperial/English uses the American standard rise over 12"
Metric Millimeters uses the rise in mm over 300mm
Decimal Inch base 10 uses the rise in decimal fractions over 10
User Input Menu Mode
- Imperial/English Inch base 12 —— default.. uses American standard pitches over 12.
- Metric 300mm base —— 300mm is 11.81102 inches, similar usage to the American framing squares printed in inches.
- Decimal Inch base 10 —— use this option when working with tangents or using the Chappell Master Framing Square
multiply the tangent of the angle by 10
- Degrees
The output mode selection can be completely different from the input mode
Output Menu Mode
- Imperial/English Inch base 12 —— default.. uses American standard pitches over 12.
- Metric 300mm base —— 300mm is 11.81102 inches, similar usage to the American framing squares.
- Decimal Inch base 10 —— use this option when working with tangents or using the Chappell Master Framing Square
No Metric to Inches Conversions are required. Enter the pitch in inches and see the results in Metric. French Compagnon charpentiers can work right along side of American carpenters or Australian and British chippys without worring about coverting between Metric, Imperial or Base 10.
Current version 2.62 functions supported:
- Frieze Block Angles
- Frieze Block Miter Angles
- Frieze Block Saw Blade Bevel Angles
- Hip Rafter Roof Angles
- Framing Square Usage for Imperial/English/Metric/Base 10
- Purlin Rafter Angles
- Purlin Rafter Miter Angles
- Purlin Rafter Saw Blade Bevel Angles
- Purlin Rafter Lip Cut Angles
- Hip Rafter Roof Angles
- Framing Square Usage for Imperial/English/Metric/Base 10
- Square Tail Fascia Angles
- Square Tail Fascia Miter Angles
- Square Tail Fascia Saw Blade Bevel Angles
- Square Tail Fascia Hip Rafter Miter Angles
- Square Tail Fascia Hip Rafter Saw Blade Bevel Angles
- Hip Rafter Roof Angles
- Framing Square Usage for Imperial/English/Metric/Base 10
- Bay Window Roof Rafters
- Hexagon Rafter Angles & Lengths
- Octagon Rafter Angles & Lengths
- Dodecagon Rafter Angles & Lengths
- Polygon Rafter Angles & Lengths
Use any part of the polyon as input to find the rest of the angles.
- Common Rafter Run
- Side Wall Length
- Half of Side Wall Length
- Radius
- Hip Rafter Run
- Hip Rafter Length
- Common Rafter Length
- Circumscribed to Radius
- Inscribed to Radius
- Common Rafter Rise
- Timber Framing Angles
- Hawkindale Angles
Use SS or S with DD or D to find the rest of the angles Timber Framing Angles or Hawkindale Angles.
- Hip/ Valley Rafter Roof Angles for equal and unequal roof pitches for any plan angle
- Hip Rafter Backing Angles
- Hip Rafter Plumb Backing Angle
- Hip Rafter Side Cut Angles
- Jack Rafter Side Cut Angles
- Roof Sheathing Angles
- Hip Rafter Purlin Housing Angles
- Hip Rafter Diamond Post Miter & Saw Blade Bevel Angles
- Plywood Roof Sheathing Offset Cut Line
- Valley Sleeper Miter & Saw Blade Bevel Angles
- Dormer Square Tail Miter & Saw Blade Bevel Angles
- Purlin Rafter Miter & Saw Blade Bevel Angles
- Purlin Layover cut perpendicular to roof surface plane
- Purlin Layover cut in the plane of the roof surface
- Irregular Hip roof Rafters
- Irregular Hip roof Rafters With Equal Overhang
- Rake walls.
- Hip Rake walls rotated into roof surface plane.
- Carpentry Certification in roof framing Trigonometry and Geometry.
- Tetrahedron Angles Calculator and Tetrahedron Framing Square Usage

- Dihedral Angles
- French Compagnon Roof Framing Kernel Angles and Framing Square Usage to geometrically draw out a bastard hip using a framing square.
- Crown Molding Miter and Bevel Angles Calculator for Compound Miter Saw Settings
and Rake Crown Molding Miter and Bevel Angles,Polygon Crown Molding Miter and Bevel Angles, Radius Bullnose Crown Molding Miter and Bevel Angles and width,
Horizontal to Rake Crown Molding Miter and Bevel Angles .
- Hopper Angles
- Jack Rafter Plumb Layout Marks on Hip Rafter
- Unequal Pitched Gable Rafters with Unequal Plate Heights
You can use it as a simple equal pitched gable rafter calculator or use it to calculate unequal pitched gable roofs with unequal plate heights.
- Equal Overhang Rafter Lengths
- First Jack Rafter Length To Long point of miter cut.
- Jack Rafter Length Difference @ jack rafter spacing
- Hip Rafter Backing Offset Main Perpendicular to hip rafter run line.
- Segmental Arches
- Gothic Arches
- Lofting -- Plotting Ellipses for Arches or Groin Vaults
- Groin Vault Plotting -- Lofting Equal Height Ordinates for Elliptical Cross Vault
Types of Groin Vaults Supported
- Semi-Circular Square Groin Vault
- Semi-Circular Rectangular Groin Vault
- Segmental Square Groin Vault
- Segmental Rectangular Groin Vault
- Gothic Square Groin Vault
- Gothic Rectangular Groin Vault
- Semi-Circular Hexagon Groin Vault
- Segmental Hexagon Groin Vault
- Gothic Hexagon Groin Vault
- Semi-Circular Octagon Groin Vault
- Segmental Octagon Groin Vault
- Gothic Octagon Groin Vault
- Semi-Circular Dodecagon Groin Vault
- Segmental Dodecagon Groin Vault
- Gothic Dodecagon Groin Vault
- Semi-Circular Hexadecagon Groin Vault
- Segmental Hexadecagon Groin Vault
- Gothic Hexadecagon Groin Vault
-
Alhambra Granada Ad Quadratum Ground Plan Roof Rafters
Clipped Hip Rafter Octagon Roof Framing
Prow Rafter Roof Framing Angles
Octagon Roof Framing 4 Butt Hip Rafter Method
Octagon Roof Framing 4 Butt Hip Rafter Method with Purlin Structural Ring
Octagon Roof Framing With Hip Rafters Mitered
Octagon Roof Framing with Gazebo Cupola
Law of Sines Formulas Reference Sheet
Rectangular Pyramid Hip Roof Geometric & Trigonometric Roof Framing Development for Bastard Hip Roofs
CutIn Dormer Shed Roof Rafter Calculator
Pitch Break Shed Roof Rafter Calculator
Dormer Shed Roof Rafter Calculator
devers de pas for Skewed Rafters rotated into the roof surface plane
Circular Stairs
Spiral - Helical Stairs
Tangent Hand Railing
Trapezoid With Unequal Overhang
Trapezoid With Equal Overhang
Platonic Solids
Archimedean Solids
Rafter Tools App current version 2.62
Functions that will be added soon:
- Radius Rafter Tails -- Ski Slope Rafters
- Curved Elongated Hexagon Roof Framing
- Curved Elongated Octagon Roof Framing
Rafter Bevel Angles App current version 1.06
- Jack Rafter Plumb To Earth Bevel Angles.
- Jack Rafter Plumb To Earth Offset Bevel Angles.
- Jack Rafter Plumb To Roof Surface Offset Bevel Angles.
- Rafter Plumb To Earth Offset Bevel Angles.
- Crossing Jack Rafters Plumb To Roof Surface Bevel Angles.
- Saint Andre Cross Rafters Plumb To Roof Surface Bevel Angles.
- Purlin Rafter Plumb To Roof Surface Bevel Angles
- Witches Cut on Hip Rafter with Square Tail Rafters Berechnung der Hexenschnittschmiegen,
- Hip Rafter Edge Bevel Angles, Backing Angles, Dihedral Angle
- Devers De Pas for Jack Rafters Plumb To Roof Surface
- tréteau à dévers... Trestles with tilt... Hip Rafters Rotated into the Roof Surface Plane.
- Claw Lines for the Draw Down Layout Technique
All bevel angles are referenced from the traditional layout method used by the French and Germans carpenters.
This app is for the WorldSkills Carpentry Competition training. With this app the carpenter can verify their geometric layout method while using the traditional layout geometry. It has seat lip cut angles at the hip rafter for all of different types of rotated rafters as well as Hexenschnitt Gratsparren.
Use with the French Rabattement de Surface method (folding) or the German Flachenklappung method.Basiswissen Schiften or Charpente Les Traces.
Stair Tangent for iPhone
This iPhone app is for rough frame carpenters that don't build stairs everyday, but could use an stair app calculator to check their stair building calculations.
Build a set of stairs that you are gonna be proud of. With Stair Tangent you can elimenate cumulative math errors when building - constructing stairs.
stairtangent.com