Science
How does a compass work?
A compass works because its magnetized needle aligns with Earth's magnetic field. The needle is a small magnet free to rotate, so it swings to point along the field lines — roughly toward the magnetic North Pole.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how a compass works.
Step by step
- 1The needle is a lightweight magnet free to spin.
- 2Earth itself acts like a giant magnet with north and south poles.
- 3The needle aligns with Earth's magnetic field, pointing north.
- 4Magnetic north differs slightly from true (geographic) north.
Frequently asked questions
- Why does a compass point north?
- Its magnetized needle aligns with Earth's magnetic field, which runs roughly north–south.
- Is magnetic north the same as the North Pole?
- No — magnetic north is near, but not exactly at, the geographic North Pole, and it drifts over time.
- What can disturb a compass?
- Nearby magnets, metal, or electrical currents can pull the needle off true alignment.