Free planning tool
Usable space calculator
Explore a symmetrical A-frame cross-section. Compare the full footprint with the area above your chosen headroom, and add an optional loft. All dimensions are internal, after finishes.
How the result is worked out
Above the knee wall, clear width at height z is W × (H − z) ÷ (H − K), clamped between zero and W. Area is clear width × length. Loft width uses its floor elevation; loft headroom uses elevation plus your chosen clearance.
What to keep in mind
Geometric area is not a legal living-area measurement or an approved floor plan. We do not subtract stairs, framing, partitions or furniture. Actual framing and local requirements can reduce usable space.
Read the related guide: How much usable space does an A-frame really have? →