How Far Does a Magnet's Pull Reach?
A magnet’s pull fades very quickly with distance. A 1/2 × 1/8 Inch N52 disc keeps only about a quarter of its holding force across a 1/16 inch gap, and its field fades to the strength of Earth’s own field about 5 inches away. Bigger magnets reach proportionally farther: double every dimension and you double the reach. A 2 × 1/2 Inch disc’s field stays above 10 gauss out to about 7 inches.
Field Reach by Magnet Size
The field is strongest straight out from a pole face (on the axis), so these are worst-case distances. We calculated them from the magnet’s dimensions and N52 material properties; stacked or grouped magnets reach farther.
| N52 disc (diameter × thickness) | Surface field (center) | Falls to 10 gauss at | Falls to Earth’s field (0.5 G) at |
|---|---|---|---|
| 1/8 × 1/16 Inch | about 5,100 G | 0.5 in (1 cm) | 1.5 in (4 cm) |
| 1/4 × 1/8 Inch | about 5,100 G | 1.1 in (3 cm) | 3.0 in (8 cm) |
| 1/2 × 1/8 Inch | about 3,200 G | 1.7 in (4 cm) | 4.8 in (12 cm) |
| 1/2 × 1/2 Inch | about 6,400 G | 2.6 in (7 cm) | 7.4 in (19 cm) |
| 1 × 1/8 Inch | about 1,700 G | 2.7 in (7 cm) | 7.6 in (19 cm) |
| 1 × 1/2 Inch | about 5,100 G | 4.2 in (11 cm) | 11.9 in (30 cm) |
| 1 × 1 Inch | about 6,400 G | 5.2 in (13 cm) | 14.8 in (38 cm) |
| 2 × 1/2 Inch | about 3,200 G | 6.8 in (17 cm) | 19 in (48 cm) |
Why Same-Shape Magnets Match
A 1/4 × 1/8 Inch disc and a 1 × 1/2 Inch disc are the same shape at different scales, so they have the same surface field. The bigger one simply carries that field four times farther. That’s why surface field alone doesn’t tell you how strong a magnet is. See how surface field is measured.
Pull Force Drops Even Faster than the Field
Holding force depends on how strongly the field changes over the steel, so it falls off faster than the field itself. Here’s the share of the listed pull force left when there’s a gap between the magnet and a thick steel plate:
| Gap | 1/4 × 1/8 Inch | 1/2 × 1/8 Inch | 1 × 1/2 Inch | 2 × 1/2 Inch |
|---|---|---|---|---|
| None (listed rating) | 100% | 100% | 100% | 100% |
| 1/32 in (0.8 mm) | 32% | 43% | 68% | 74% |
| 1/16 in (1.6 mm) | 15% | 26% | 52% | 60% |
| 1/8 in (3.2 mm) | 4% | 11% | 32% | 43% |
| 1/4 in (6.4 mm) | 1% | 3% | 15% | 26% |
| 1/2 in (12.7 mm) | under 1% | under 1% | 4% | 11% |
These are model estimates for an ideal thick plate; real steel, paint and alignment lower them a little. For the full explanation, read how air gaps affect magnet strength.
Rules of Thumb
Bigger Reaches Farther
Scale a magnet up 2× in every direction and its field pattern scales with it: the same strength twice as far out.
Thicker Beats Wider for Reach
A thick magnet (or a stack) throws its field farther than a thin, wide one with the same pull rating.
Far Away, It's a Cube Law
Well away from the magnet, double the distance and the field drops to about one eighth.
Need More Reach?
Use a thicker magnet or a pair of magnets instead of a magnet and steel plate. Two magnets attracting across a gap hold about twice as far as a magnet and a steel plate. See magnets through wood, drywall and glass.