Geometry breakdown
Every included and excluded area—or every polygon edge—remains auditable.
OneFreePlace · Tool #157
Measure a room as a rectangle, compose it, or map every corner.
Go beyond length × width. Calculate a simple room, build an irregular footprint from added/subtracted geometric zones, or enter polygon corner coordinates for exact shoelace area, perimeter, centroid, wall surface, room volume and an auto-scaled SVG measurement preview.
✓ Rectangle + full room metrics✓ Irregular shape composer✓ Polygon corner engine✓ Self-intersection detection✓ Live SVG preview
Room Area Calculator
rectangle · shape composer · polygon corners
Room geometry
Choose the measurement method that matches the room.
Rectangular roomUse measured interior floor dimensions. Optional exclusion removes a fixed area from floor/ceiling area but does not change the outer wall perimeter.
Height & wall openingsHeight unlocks room volume and gross wall area where a reliable perimeter exists. Door/window opening area is then subtracted from wall surface only.
Height uses feet; wall openings use ft²; price is per ft².
Room result
Calculating—
net floor area
Enter valid room geometry.
Square meters—metric floor area
Square feet—imperial floor area
Perimeter—outer wall path when available
Net wall surface—perimeter × height − wall openings
Room volume—net floor area × ceiling height
Entered-price estimate—net floor area × optional unit price
Measurement resultVerify field dimensions before using an area for purchasing, valuation, leasing or regulatory purposes.
Room preview
Diagram is schematic but numerically driven. Polygon mode uses the entered corners directly.
Dimension intelligence
Useful derived geometry without hiding the assumptions behind it.
Area conversions
The same net floor area in commonly used planning units.
Formula audit
Shows exactly how the current mode reaches its total.
Practical boundaries
Interior room area is not automatically real-estate floor areaLegal, appraisal, listing and standards-based measurements may define included space, wall thickness, stairs and low-height areas differently.
Use the right standardComposer zones must not overlap unless intendedThe composer adds and subtracts explicit shape areas; it cannot infer shared boundaries or accidental overlap.
Audit the sketchPolygon corners must follow the perimeterCrossing edges are rejected because a self-intersecting polygon is ambiguous for ordinary room measurement.
Order cornersi
Why polygon mode matters.An angled or many-cornered room does not need to be approximated by rectangles. Ordered corner coordinates let the calculator use the shoelace formula for exact planar polygon area and the actual edge lengths for perimeter.