Coolant Boiling Point Calculator

Calculate the boiling point of engine coolant based on glycol concentration and system pressure.

Percentage of ethylene glycol (antifreeze) in the coolant mixture. Most vehicles use 50/50 mix. Range: 0% (pure water) to 70% (max recommended).
%
Ethylene glycol (EG) is most common. Propylene glycol (PG) is less toxic but has slightly lower boiling point elevation.
Pressure rating of the radiator cap. Most caps are 13-16 PSI. Each 1 PSI raises the boiling point approximately 3°F (1.67°C).
PSI
Higher altitude means lower atmospheric pressure, lowering the boiling point. Sea level = 0 ft. Denver, CO is about 5,280 ft.
ft

Results

Boiling Point (with pressure cap)-°F
Boiling Point (with pressure cap)-°C
Boiling Point (no pressure cap)-°F
Elevation from Glycol-°F
Elevation from Pressure-°F
References:
Boiling point elevation from ethylene glycol: 0%=212°F, 50%=226°F, 60%=232°F, 70%=235°F at sea level unpressurized. Each PSI of cap pressure adds ~3°F. Altitude reduces boiling point ~1.8°F per 1,000 ft. Based on standard coolant chemistry data (ASTM D3306).