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What is RoomPlan, and how does it work?

RoomPlan is Apple's built-in room scanner for developers: it uses LiDAR and machine learning to recognise walls, doors, windows and furniture as you walk around a room. It is not an app you can download — it is the engine under many of them.

RoomPlan is an engine, not an app

Many people think RoomPlan is an app, because it is mentioned in the description of several scanning apps. It is a developer tool: a piece of code Apple provides so app makers do not have to build a room scanner from scratch. That also explains why so many LiDAR scanners for iPhone feel similar to use — they are looking at the room with the same engine, but each wraps the result differently.

The difference between the apps therefore rarely lies in the scan itself. It lies in what happens afterwards: whether you get a floor plan with measurements on it, whether you can correct a crooked wall, whether you can work out areas and materials, whether you can get the file back out again — and where your data ends up.

What RoomPlan sees

What sets RoomPlan apart is that it does not just produce a point cloud of surfaces. It tries to understand what it is looking at, and delivers named building elements:

• Walls — with position, length, height and a thickness.
• Doors and windows — as holes in a particular wall, with width, height and how far above the floor they sit.
• Openings — doorless passages, for example between a kitchen and a living room.
• Furniture by category — among others sofa, bed, table, chair, storage, kitchen and appliance types, and stairs. RoomPlan guesses the type and places a box of roughly the right size; it does not create a faithful copy of your actual sofa.

That difference is the whole point. An ordinary 3D scan produces a lump of geometry, where a door is just a hole in a surface. RoomPlan gives you a door that knows it is a door, sits in a particular wall, and is 82.5 cm wide. That is the kind of data you can turn into a floor plan, a door schedule and a takeoff.

How a RoomPlan scan happens

From the user's side, it looks like recording a video. You start the scan, hold the phone at roughly chest height, and walk slowly around along the walls, letting the camera sweep across floor, walls and ceiling. As you go, the app draws a simple white wireframe over the image, so you can see what has been captured and what is still missing.

RoomPlan works in two layers at once: LiDAR measures the distance to the surfaces, and machine learning decides what the surfaces are. That is why the model can correct itself as you go — a surface first read as a wall can turn into a window once you get closer.

Multiple rooms: later versions of RoomPlan can stitch several scans together into a single building. That is necessary because each room is processed in its own coordinate system — only once the rooms are merged is it known how they sit in relation to one another. The merging happens on the device itself.

What RoomPlan requires

• LiDAR. iPhone 12 Pro, 13 Pro, 14 Pro, 15 Pro, 16 Pro and 17 Pro — and their Max versions — plus every iPad Pro from 2020 onwards. Models without "Pro" in the name do not have it, nor do the Plus models. This list is a snapshot — new Pro models keep arriving.
• Reasonable light. LiDAR works in the dark, but the machine learning that recognises doors and furniture looks at the camera image and needs to be able to see.
• Room to walk. The scanner needs to be able to get around along the walls. A room full of moving boxes turns into a room with box-shaped walls.

What RoomPlan does not do

• It does not say whether a wall is load-bearing. RoomPlan measures where the wall stands and guesses a thickness. What the wall is holding up is something neither LiDAR nor machine learning can see. That question needs a building surveyor or an engineer.
• It does not produce a floor plan by itself. RoomPlan delivers geometry. The drawing itself — lines, dimensions, areas, north arrow — is built by the app on top.
• It cannot see through things. Curtains, wardrobes and stacked boxes become the surface the scanner can see. The wall behind is never found.
• It handles glass and mirrors poorly. A large mirror can look like an opening into a room that does not exist.
• It does not automatically give perfectly square corners. Raw RoomPlan walls are rarely exactly 90 degrees to one another. Apps typically straighten them out afterwards. The line itself may be tidied up, as long as the measurements stay exactly as measured.

What HouseSense builds on top of RoomPlan

HouseSense uses RoomPlan for the scan itself and builds the rest from there. The scans of the individual rooms are merged on the phone into one coherent building, and out of that comes a measured floor plan with areas per room, a takeoff for contractor quotes, a window and door schedule, a 3D model with true sunlight based on the home's location and north direction, budget and PDF reports. The drawing can be corrected afterwards: walls moved, measurements typed in.

All of it runs on the device. There is no account and no server; the scans live in your own iCloud.

If your phone does not have LiDAR

Then you cannot use RoomPlan — full stop. There is no setting that unlocks it, and an app that claims to use RoomPlan without LiDAR is doing something else. There are, however, two ways around it: camera-based AR apps, which measure from the image alone and are more sensitive to light and plain-coloured walls, and drawing apps, where you measure with a tape measure or a laser yourself and type the numbers in. That last route is slower, but the figures are exactly as good as your own measuring — and it works in a dark, empty house where no scanner can keep up.