Straight Closed Stringer Staircase Calculator

Straight Closed Stringer Staircase Calculator

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Staircase Type
Stairs Dimensions, Stairwell
Upper Floor Slab
Error calculationPlease check your input
the Calculator will be available after changes in the relevant parameters.
Click "Calculate" to open the options window.
Choose Drawing:
Distance: 0
Calculation results
Staircase Dimensions
  • Angle: 32.69 °
  • Comfortable Staircase Formula (R + G): 45.15 cm
  • Blondel's Formula (2R + G): 62.79 cm
  • Rise: 17.65 cm
  • Tread Depth: 33.3 cm
  • Going (Run): 27.5 cm
  • Number of Steps: 16 pcs.
  • Staircase Width: 100 cm
  • Minimum Throat Depth: 30.38 cm
Materials for construction
  • Width: 31.35 cm
  • Length: 540.75 cm
  • Thickness: 6 cm
  • Quantity: 2 pcs.
  • Wood Volume: 0.203 m3
  • Tread Depth: 33.3 cm
  • Length: 88 cm
  • Thickness: 4 cm
  • Quantity: 16 pcs.
  • Wood Volume: 0.188 m3
  • Width: 13.65 cm
  • Length: 88 cm
  • Thickness: 1.8 cm
  • Quantity: 16 pcs.
  • Wood Volume: 0.035 m3
  • Handrail Width: 8 cm
  • Handrail Thickness: 4 cm
  • Handrail Length: 538.67 cm
  • Wood Volume: 0.017 m3
  • Width: 5 cm
  • Length: 86.85 cm
  • Quantity: 17 pcs.
  • Wood Volume: 0.037 m3
Initial parameters
Staircase Type
  • Left Turn:  selected
Stairs Dimensions, Stairwell
  • Total Rise: 300 cm
  • Total Run: 450 cm
  • Staircase Width: 100 cm
  • Quantity: 16 pcs.
  • Thickness: 4 cm
  • Nosing (Tread Overlap): 4 cm
  • Thickness: 6 cm
  • Thickness: 1.8 cm
Upper Floor Slab
  • Slab Overlap: 100 cm
  • Thickness: 20 cm
  • Handrail Height: 90 cm
  • Baluster Width: 5 cm
  • Handrail Thickness: 4 cm
  • Handrail Width: 8 cm
  • Thickness: 20 cm
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Please make sure your stair design complies with all local building codes and regulations requirements! It is very crucial step


Calculator of closed stringer stair (solid, housed, routed)

Straight flight closed stringer stair is a single-flight construction with a solid / glued wooden beams as supporting elements. It is the simplest construction in terms of manufacturing and assembly, since it does not require the creation of a saw-tooth stringer and constant monitoring of compliance with the minimum throat depth, and also involves a greater number of methods for mounting treads (fitting into a housed stringer, treads supported by cleats ...). The main disadvantage is the cumbersome design and the need to create a wider stairwell opening, compared with the saw-tooth stringer.

The online calculator for calculating straight wooden closed stringer stairs allows you to determine the parameters of all the components of the structure, calculate the amount of necessary materials for construction, draw up detailed drawings with scale and visualize the stairs in the form of a 3D model. Also, the tool automatically provides recommendations for creating the most ergonomic design. All calculations are performed on the basis of mathematical formulas, excluding the occurrence of random errors.

Stair calculation step by step

  • Step 1 . Select units of measurement - mm, cm, m, inches, feet.
  • Step 2 . Choose the type of drawing - b&w, color.
  • Step 3 . Determine the type of staircase configuration - with a left turn, with a right turn.
  • Step 4 . Determine the staircase dimensions - Total Run, Stair Width, Total Rise (if the upper step is at the level of the 2nd floor, stairwell opening height = staircase height).
  • Step 5 . Fill in the steps dimensions and related values ​​- number of steps, thickness of the tread, nosing (protrusion beyond the riser), choose option: the upper step below the level of the 2nd floor or at the level.
  • Step 6 . Determine stringer parameters - beam thickness, stringer height above the nosing line and below a layout line, distance from seat cut toe to the 1st step (including the riser thickness and the step protrusion or nosing). See more details in the drawings.
  • Step 7 . Fill in the risers parameters (optional).
  • Step 8 . Choose dimensions of the Stair Railing - height of the handrail, baluster width, handrail thickness and width.
  • Step 9 . Slab overlap and walls - it is necessary to fill in for correct 3D visualization (it does not affect the configuration of the stairs).
  • Step 10 . Confirm the entered data and the begin the housed stringer staircase calculation by clicking on “Calculate”.


In order to create the most comfortable straight staircase with the help of our calculator, it is necessary to carry out the calculation based on the exact double-checked data of the opening measurement, and also use the parameters of the main structural elements in compliance with Building regulations.

The values used are obtained on the basis of the “convenient staircase” formula of the French architect Francois Blondel and have been actively used by technical specialists for several centuries.

Blondel formula: 2 × r + g = 63- 65 cm,

  • r — step height (rise);
  • g — step width (run, going);
  • 63/65 cm — the average stride length of a person.

There are also two formulas for planning comfortable staircases among carpenters:

  1. Formula r+g =18 inches (or 17 -19). Rise plus Run equal 18 inches.The IRC limits h+s on 17 ¾” (7 ¾” + 10”)
  2. Formula 2r+g=25 inches. Two rises plus one run equal of 25 inches. The IRC limits 2h+s of 25 ½” (2*7 ¾” + 10”)

It is crucial to comply building codes and state standards, as well as other technical documents for designing comfortable straight stairs, but also safe and strong enough to withstand the necessary loads. The calculator does not take these features into account, but nevertheless does not allow you to enter critically invalid values. The Building Codes  and regulations   vary  considerably between  countries, between states and regions.  We will give you some information for USA, UK, Australia.

Stair Riser and Going Dimensions (mm) - USA
     Picture 1. Stair Riser and Going Dimensions for USA
Stair Rise and Going Dimensions - Australia
   Picture 2. Stair Rise and Going Dimensions for Australia

"The height of a balustrade or other barrier must be not less than 1 m above the floor of any access path, balcony, landing, etc, and not be less than 865 mm above the nosings of the stair treads or the floor of a ramp."

Stair Rise and Going Dimensions - UK
   Picture 3. Stair Rise and Going Dimensions (mm) - UK Building Regulations 2010 Part K, 2013 edition

1. The maximum pitch for a private stair is 42°

2. For dwellings, external tapered steps and stairs that are part of the building, the going of each step should be a minimum of 280 mm.

Headroom - at least 2m

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