Enter room dimensions to get detector count and grid spacing per AS/NZS 1670.1. Ceiling height penalty included.
Under AS/NZS 1670.1, the maximum centre-to-centre spacing for photoelectric or ionisation smoke detectors is 7.5 m for ceilings up to 3.5 m high. High ceilings reduce effective spacing. Heat detectors have a maximum spacing of 5.3 m.
AS/NZS 1670.1 requires detectors to be at least 500 mm from walls or ceiling–wall junctions. Detectors should not be installed in "dead air" zones where smoke may not reach, such as corners of rooms with low air circulation.
New Zealand recommends photoelectric smoke alarms as the preferred type for residential use. They are more responsive to slow-smouldering fires (which are more common in homes) and produce fewer nuisance alarms from cooking.