Free specialty workspace
Construction calculator
Use this construction calculator for feet, inches and fractions, right-triangle dimensions and equal stair-rise layouts.
Method version1.0.0 · Reviewed November1,2026 · Calculated on your device
Your calculation
Choose a method, then enter your figures. Examples are illustrative, not recommended settings or rates.
How this calculation works
Length addition/subtraction; area = length × width; diagonal = √(run²+rise²); stair risers = ceiling(total rise ÷ chosen maximum rise).
What information do I need?
Only fields for your selected method are required. Use consistent units and scope. Changing an entry method or unit system does not convert the numbers already entered. Previously calculated results are cleared when inputs change.
Input definitions and where to find them
- What would you like to calculate?
- Choose the method matching your inputs.
- Arithmetic operation
- Choose the dimensional result you need.
- First dimension
- Use decimal feet or feet/inches with a fraction:5 ft 6 1/2 in.
- Second dimension
- Use the same feet-inch notation. Plain numbers are feet.
- Horizontal run
- Horizontal distance, not the sloped measurement.
- Vertical rise
- Vertical difference between the endpoints.
- Finished-floor to finished-floor rise
- Measure finished surfaces; do not use ceiling height.
- Your maximum permitted or chosen riser height (in)
- Supply the applicable limit yourself; no building-code value is selected for you.
- Your chosen tread depth (in)
- Chosen depth excluding any separately considered nosing. Upper landing is the final walking surface.
Worked example
This example uses the initial method shown in the selector. Load an example in the form to try it.
Example inputs
- What would you like to calculate?: dimension
- Arithmetic operation: add
- First dimension: 5 ft 6 1/2 in
- Second dimension: 2 ft 3 1/2 in
Example answer: Result = 7.83333333 ft
Use the result well
Plain numbers are decimal feet. Fractional feet-inch display is rounded; arithmetic retains full entered precision.
Review the limits shown with each result. Browser arithmetic has finite precision; small differences may reflect rounding. Print or download important results before closing the tab. This workspace does not store projects online or replace an approved examination calculator, engineering design or professional judgment.
Method and sources
References support the stated mathematical concepts; the interface and implementation are original. Publishers do not endorse this site.