How to Measure Heights Using Your iPhone Camera

Modern iPhones are equipped with sophisticated sensors and advanced computational photography capabilities that go far beyond taking standard photos. One of the most practical built-in tools is the ability to measure real-world objects, distances, and even people’s heights using nothing but your phone’s camera and LiDAR scanner (on Pro models).

Whether you need to quickly check if a piece of furniture will fit in your living room, or you want to measure someone’s height without a tape measure, the pre-installed Apple Measure app provides surprisingly accurate results.

Requirements for Measuring Height

To measure a person’s height instantly using the automated feature, you need:

• An iPhone 12 Pro, iPhone 12 Pro Max, or any newer Pro/Pro Max model (13 Pro, 14 Pro, 15 Pro, etc.).
• An iPad Pro 11-inch (2nd generation and later) or iPad Pro 12.9-inch (4th generation and later).

These specific devices feature a LiDAR (Light Detection and Ranging) scanner on the rear camera bump, which fires invisible laser pulses to map the 3D environment instantly. Standard iPhones (like the iPhone 13, 14, or 15 non-Pro models) can still measure objects manually, but they lack the automated instant height detection.

How to Measure a Person’s Height Automatically (Pro Models Only)

If you have a supported Pro device, measuring someone’s height is entirely automatic:

1. Locate and open the Measure app. It comes pre-installed on all iPhones. If you deleted it, you can redownload it for free from the App Store.
2. Ensure the person you want to measure is standing straight.
3. Point your iPhone camera at them, ensuring their entire body (from the floor to the top of their head) is visible within the frame.
4. Wait a moment. The app will automatically detect the person.
5. A horizontal line will appear resting on top of the person’s head (or hair/hat), with their exact height measurement displayed below the line.

Important Tips for Automatic Measurement

• Lighting matters: Ensure the room is well-lit. The LiDAR scanner works in the dark, but the camera needs light to identify the person’s boundaries.
• Distance: Stand about 2 to 3 metres (6 to 9 feet) away from the person. If you are too close, their whole body will not fit in the frame; if you are too far, the measurement may be less accurate.
• Headwear and hair: The app measures to the highest point it detects. If the person is wearing a tall hat or has very voluminous hair, the measurement will include it.
• Taking a photo: Once the measurement appears, tap the circular shutter button in the bottom right corner to take a photo containing the measurement overlay. This saves directly to your Photos app.

How to Measure Objects Manually (All iPhone Models)

If you have a standard iPhone without a LiDAR scanner, or if you need to measure an object rather than a person, you can use the manual measurement tool.

1. Open the Measure app.
2. The app will instruct you to move your iPhone around slowly. This helps the camera understand the physical space, floor, and surfaces.
3. Once calibrated, a white dot with a circle around it (a reticle) will appear in the centre of your screen.
4. Point the white dot at the starting point of the object you want to measure.
5. Tap the + (Add) button at the bottom of the screen.
6. Slowly pan your iPhone across the object until the white dot reaches the end point. You will see a yellow line drawing between your start point and current position.
7. Tap the + (Add) button again to lock in the end point.
8. The measurement will be displayed on the line.

Measuring Rectangular Objects Automatically

The Measure app is intelligent enough to recognise clear rectangular objects, such as a piece of paper on a desk, a picture frame on a wall, or a television screen.

1. Point the camera at the rectangular object.
2. The app will automatically detect its edges and highlight it with a yellow bounding box.
3. Tap the + (Add) button.
4. The app will instantly calculate and display both the length and width of the object.

How Accurate is the Measure App?

The accuracy depends heavily on which iPhone model you are using:

iPhones with LiDAR (Pro models): These are highly accurate, usually within a few millimetres or half an inch. LiDAR maps the environment using light pulses, making it much more reliable than camera optics alone.

Standard iPhones: These rely on ARKit (Augmented Reality Kit) software estimating depth from the standard camera lens. While generally reliable for rough estimates (usually within 1 to 2 inches of accuracy), they should not be used for precision tasks like ordering custom-fitted glass or cutting expensive building materials. Always double-check with a physical tape measure for critical tasks.

How to Change Measurement Units (Metric vs Imperial)

By default, the Measure app uses your region’s standard measurement system. If you need to switch between inches/feet and centimetres/metres:

1. Open the Settings app on your iPhone.
2. Scroll down and tap Measure.
3. Under the “Measure Units” section, select either Imperial or Metric.
4. Return to the Measure app — your existing and future measurements will instantly update to the new system.