What Is the Half-Turn Calculator?
Plan half-turn stairs (also known as dog-leg stairs) with two parallel flights and a 180-degree landing. This configuration is the most common in two-story residential construction and provides excellent fall protection through the mid-flight landing.
How to Use This Calculator
- Enter the total floor-to-floor rise.
- Configure tread depth, width, and landing size.
- Review the split between upper and lower flights.
Why Accurate Half-Turn Calculations Matter
Half-turn stairs are space-efficient because both flights stack above each other. The landing width determines the overall stair footprint, and the well opening between flights must be wide enough for handrails on both sides.
Common Half-Turn Mistakes to Avoid
- Assuming a dog-leg stair (no well opening) and a true half-turn stair (with a well) use the same handrail layout. A dog-leg often needs only one continuous rail; a half-turn with a well usually needs rails on both flights.
- Making the landing narrower than either flight above or below it. Landing width has to match the wider of the two connecting flights, not just the average.