Convert pounds per square inch to standard atmospheres

One pound per square inch is 0.0680459639 standard atmospheres. To convert any amount, multiply by 0.0680459639. Going the other way, one standard atmosphere is 14.6959488 pounds per square inch.

Multiply the pound per square inch figure by 0.0680459639. So atm = psi × 0.0680459639. For a quick mental estimate, dividing by about 14.7 gets you close enough for most everyday purposes.

One pound per square inch is a car tyre runs about 32 psi. Psi is the tyre-pressure unit in North America. Car tyres typically run 30–35 psi, and getting this wrong measurably affects both fuel economy and braking distance.

One standard atmosphere is sea-level air pressure by definition. One standard atmosphere is defined as exactly 101,325 pascals. It is a reference value rather than a measurement of the actual air pressure today.

Yes. Since the 1959 international yard and pound agreement, the imperial and metric systems are related by exact definitions rather than measurements — the inch is exactly 25.4 mm and the pound exactly 0.45359237 kg. Everything derived from those, including this conversion, is therefore exact. Round at the end rather than partway through, since rounding psi before converting introduces an error the conversion then multiplies.