Side-by-side comparison
- Propane (C3H8): boiling point -44°F, storage pressure ~120 psi at 70°F, energy density ~91,500 BTU/gallon
- Butane (C4H10): boiling point ~32°F, storage pressure ~30 psi at 70°F, energy density ~103,000 BTU/gallon
Why propane wins in the US
Butane's boiling point of 32°F means that in cold weather, liquid butane stops vaporizing — appliances connected to a butane tank simply don't work when temperatures drop. Propane vaporizes down to -44°F, well below typical US winter conditions. In a country where most LPG demand is winter heating in northern states, butane is impractical.
Where butane appears
Butane has a residential role in warm-climate countries (most Mediterranean Europe, Latin America, Southeast Asia) where temperatures rarely drop below freezing. In the US, butane shows up primarily in:
- Cigarette lighters and small portable cookers
- Refrigerants in some commercial systems
- Industrial chemical feedstock
- Gasoline blendstock (some butane is added to winter-grade gasoline)
Blends and grades
US-sold residential propane is graded HD-5 by ASTM D1835 — minimum 90% propane content, with limits on butane, propylene and impurities. International LPG markets often use propane-butane blends with seasonal variation (more butane in summer, more propane in winter). See propane quality and grades.
FAQ
Can butane and propane be used in the same appliances?
No, not without modification. Different appliance orifice sizes and regulator pressures are needed. Propane appliances will not work safely on butane and vice versa. Hardware manufacturers sell conversion kits for some appliances.
Is butane cheaper than propane?
Globally, butane and propane wholesale prices track each other closely with small spreads driven by seasonal demand. In US retail markets, butane is essentially not sold to residential heating customers — the comparison doesn't arise.