Cómo medir una habitación con tu iPhone (guía paso a paso)

A tape measure is great for one wall at a time. But if you need a full room, every wall, every door, every window, there's a faster way. Your iPhone can capture the whole room in under five minutes, give you a measured 2D floor plan, export a PDF you can email to a contractor, and (on newer models) build a full 3D model you can walk through.

This guide walks you through both methods: the automatic LiDAR scan for iPhones with a depth sensor (12 Pro and newer), and the manual floor plan builder that works on every iPhone from the Xs onward. We'll use the free Ruler AR app for both, but the techniques apply to any AR-based measuring app.

Before you start

Both methods rely on Apple's ARKit framework, which tracks your phone's position in physical space using the camera and motion sensors. To get accurate results:

• Good lighting. ARKit needs visible texture to track surfaces. A daylit room or evenly lit indoor space works best. In dim conditions, the app will prompt you to turn on the flashlight.
• Clear floor path. You'll walk the perimeter of the room. Move chairs out of the way before you start, you can put them back after.
• Steady hands. Hold the phone like you're filming a movie: two hands, elbows in, slow movements. Jerky motion confuses the tracker and ruins accuracy.

Method 1: LiDAR scan (iPhone 12 Pro and newer)

If your iPhone has a LiDAR sensor, the small black dot next to the rear camera lenses on Pro models, you can use Apple's RoomPlan technology to generate a complete 3D floor plan. The phone identifies walls, doors, windows, and furniture automatically.

1. Open the Room Plan tool. In Ruler AR, tap the Tools button and choose Room Scan. Grant camera access if prompted.
2. Stand in a corner of the room. Face the opposite corner diagonally. The app will show a preview of the 3D model being built, start out at chest height, phone in landscape orientation.
3. Walk slowly along each wall. Pan the phone in a smooth arc to capture the wall from floor to ceiling. Take your time at the corners, that's where AR tracking can drift.
4. Loop the entire room. When you return to your starting corner, the floor plan should be complete. The app will detect doors, windows, and major furniture (sofa, bed, table, fridge…) and tag them.
5. Save and export. Tap Done. You'll see a 3D preview, a 2D floor plan, and dimensions for every wall. From here you can export to PDF, share a USDZ 3D model, or copy individual measurements.

On a 4×5 m bedroom this takes about 90 seconds. Accuracy is typically ±5 mm because LiDAR measures depth directly rather than inferring it from camera frames.

Method 2: Manual floor plan builder (any iPhone Xs or newer)

No LiDAR? You can still build a clean orthogonal floor plan by walking the perimeter and tapping corners. This is slower than the LiDAR scan but produces a measured 2D plan that's accurate enough for renovation estimates, furniture shopping, and listing photography.

1. Stand in a corner. In Ruler AR, open the Toolsmenu and choose Manual Room Builder. Stand in any corner of the room, facing the wall you want to start with.
2. Tap the corner where you're standing. Aim the on-screen crosshair at the floor at the base of the corner and tap. The app marks this as your first vertex.
3. Walk along the wall. Move to the next corner. The app shows a live preview of the wall length growing in real time.
4. Tap the next corner. Repeat for every corner of the room. The mini-map in the top-right shows the polygon taking shape.
5. Close the loop. When you return to your first corner, the "Close room" pulse appears. Tap it. The app snaps walls to right angles (within ±15°), removes any tiny segments, and produces a clean floor plan.

Tip: if you make a mistake, long-press a corner to delete it. Or use the Undo/Redo buttons at the bottom of the screen. Your work is auto-saved every second, even if you minimize the app or the phone locks, the in-progress scan survives.

Capturing doors, windows, and furniture (manual method)

Manual scans capture the room outline but not the openings. To add them:

• After closing the room, the 2D editor opens. Drag and drop a door icon onto the wall where the door is. Set its width and height.
• Do the same for each window. Set the sill height (from floor) and the opening dimensions.
• For furniture, use the object library, sofa, bed, table, fridge, etc. Drag onto the plan, then rotate and resize.

Exporting your floor plan

Every scan you save becomes a project in your library. From any project detail screen you can:

• Export PDF. A4 layout with the 2D floor plan, a dimensions table for every wall, and an optional material estimate (paint, flooring, baseboard, tile, wallpaper).
• Share a screenshot. The 2D plan as a PNG. Works great in iMessage and email.
• Export 3D (LiDAR only). USDZ format, opens in macOS Quick Look, AR Quick Look on iPhone, or any 3D modeling tool.

When to use each method

Common mistakes (and how to avoid them)

• Scanning in low light. AR tracking degrades fast. Either turn on overhead lights or use the in-app flashlight.
• Moving too fast. AR sessions need about 50ms per frame to update. If you whip the phone around, tracking falls behind and walls end up bent. Walk slowly.
• Skipping the corner. Don't shortcut across the room. AR drifts over distance; walking the perimeter resets tracking at every corner you tap.
• Reflective surfaces. Mirrors and full-length glass windows confuse depth tracking. Cover them with a sheet during the scan and add them as objects in post.

Ready to try it?

Ruler AR is free on the App Store. The Manual Room Builder works on any iPhone Xs or newer; the LiDAR scanner is included on Pro versions of the iPhone 12 and up. Open the camera, walk the room, share the PDF, done in five minutes.