Measure Pro

Stud finder for iPhone: it finds the screws and nails

The Stud Finder tool uses your iPhone’s magnetometer, the sensor behind the compass, to find iron and steel. In a wall, that means the screws and nails that fix the board to a wooden stud, or a steel stud itself. It can’t find wood, copper pipes, plastic pipes or electrical wires, and no phone can. Never drill using this tool alone: always check the wall another way first.

How to use it

1. Hold the phone flat against part of the wall with no metal behind it and tap Set zero.
2. Move the phone slowly up and down, then a little to the side, and repeat. Keep it flat.
3. When the line rises above the dashed line, there is metal. The marked high point shows where.
4. Keep other electronics, including other stud finders, about 30 cm (12 in) away. Their batteries and magnets throw off the sensor.

Good for

• Finding the line of screws or nails where a board is fixed to a stud
• Finding steel studs
• Checking baseboards, where nails usually go into the studs

What it can’t do

• It finds iron and steel only. It cannot find wood, copper pipes, plastic pipes or electrical wires.
• It only notices a screw when it passes within about 2 cm (1 in) of the sensor, which sits near the top of most iPhones.
• Never drill using this tool alone. Always check the wall another way first.