Antifreeze Mix Ratio Calculator
Calculate the right antifreeze-to-water ratio for your climate.
Find freeze point and boil-over protection temperatures.
Antifreeze (engine coolant) is mixed with water to protect the engine from freezing in winter and overheating in summer.
Standard mix ratios:
- 50/50 (antifreeze/water): The most common recommendation. Protects to -34°F (-37°C) freeze point and 265°F (129°C) boiling point.
- 60/40: Better freeze protection to -62°F (-52°C). Recommended for very cold climates.
- 70/30: Maximum freeze protection to -84°F (-64°C). Used in extreme Arctic conditions.
- 30/70: Minimal protection to -10°F (-23°C). Not recommended for most climates.
Important: Never use pure antifreeze. Pure antifreeze actually freezes at a higher temperature (-8°F / -22°C) than a 50/50 mix. It also transfers heat less efficiently, which can cause engine overheating.
Never use pure water either. Water alone freezes at 32°F (0°C) and provides no corrosion protection. It also boils at 212°F (100°C) — too low for modern engines under pressure.
Coolant system capacity varies by vehicle:
- 4-cylinder cars: 6-8 quarts (5.7-7.6 liters)
- 6-cylinder cars: 10-12 quarts (9.5-11.4 liters)
- V8 / Trucks: 12-16 quarts (11.4-15.1 liters)
- Large trucks/SUVs: 16-24 quarts (15.1-22.7 liters)
Types of antifreeze:
- Green (IAT): Traditional formula. Change every 2 years / 30,000 miles.
- Orange (OAT/Dex-Cool): Extended life. Change every 5 years / 150,000 miles.
- Yellow/Purple (HOAT): Hybrid formula. Change every 5 years / 150,000 miles.
Never mix different types unless the manufacturer explicitly allows it. Mixing can cause gelling and clogging.