Monthly rent and floor area in square meters—rent per m² per month (any currency).
Monthly rent is divided by area in square meters (must be positive); rent must be non‑negative. A second line multiplies by 12 as a simple per‑m² yearly figure in the same unit system.
This calculator uses plain decimal numbers. If a result looks wrong, check whether you used a comma instead of a dot (or vice versa) where the field expects one.