Below vs. Under

The prepositions below and under can both mean lower than. But there are some differences.

Below

Below is preferred when one thing is not directly under another.

• When the sun sets, it sinks below the horizon.

Below is used in measurements of temperature and height, and in other cases where we think of a vertical scale.

• The temperature is 10 degrees below zero.
• The Dead Sea is below sea level.
• She is below average in intelligence.

Under

We prefer under when something is covered or hidden by what is over it.

• I think the cat is under the bed.
• The whole village was under water.

We usually use under, not below, to mean less than or younger than.

• There were under fifty people at the meeting.
• You cannot see this film if you are under 18.