Compression Ratio Calculator

Compression ratio is absolute discharge pressure divided by absolute suction pressure.

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Formula

Ratio = (discharge psig + atm) ÷ (suction psig + atm)

Example calculation

Suction 118 psig, discharge 340 psig at sea level → 354.7 ÷ 132.7 = 2.67.

Practical HVAC use

High ratios raise discharge temperature and reduce compressor efficiency; useful when diagnosing low suction or high head.

Common mistakes

Dividing gauge pressures directly — always convert to absolute first.

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Educational tool. Results are estimates from the stated formulas; always confirm with manufacturer data and the code adopted in your jurisdiction. All calculators