How Many Pounds in a 100 Gallon Propane Tank?
Calculate propane tank weight, capacity, fill cost, and usage time. Works for all tank sizes from 20 lb BBQ tanks to 1000 gallon home tanks.
Quick Answer: 100 Gallon vs 100 lb Tank
• 100 gallon tank: Holds ~424 lbs propane (80 gal at 80% fill) | Full weight: ~555 lbs
• 100 lb tank: Holds ~23.6 gallons propane | Full weight: ~170 lbs
Key formula: 1 gallon propane = 4.24 lbs | 1 gallon = 91,500 BTU
📊 Select Tank Size
⚠️ Important: lb vs Gallon Tanks
- Lb tanks (20, 30, 100 lb): Portable cylinders rated by propane weight
- Gallon tanks (100-1000 gal): Stationary tanks rated by volume
- All tanks filled to max 80% for safety expansion room
📋 Tank Specifications
⚠️ 80% Rule: Filled to 80% = 80 gallons for safety
📋 Quick Reference: Propane Tank Sizes
| Tank Size | Propane Gallons | Full Weight | Fill Cost | BBQ Runtime |
|---|---|---|---|---|
| 20 lb (BBQ) | 4.7 gal | 37 lbs full | $15-25 | 15-20 hrs |
| 30 lb | 7.1 gal | 55 lbs full | $22-35 | 22-30 hrs |
| 100 lb | 23.6 gal | 170 lbs full | $60-90 | 70+ hrs |
| 100 gallon | 80 gal* | 555 lbs full | $200-320 | N/A |
| 250 gallon | 200 gal* | 1,335 lbs full | $500-800 | N/A |
| 500 gallon | 400 gal* | 2,650 lbs full | $1,000-1,600 | N/A |
* Gallon tanks shown at 80% fill capacity. BBQ runtime based on 30,000 BTU grill.
⛽ Understanding Propane Tank Sizes
Propane tanks come in two main categories: portable cylinders measured in pounds (lb) and stationary tanks measured in gallons. Understanding the difference is crucial for calculating capacity, weight, and cost.
Key Conversion Factors
- 1 gallon propane = 4.24 pounds (at 60°F)
- 1 gallon propane = 91,500 BTU of energy
- 1 pound propane = 21,591 BTU of energy
- Max fill = 80% of tank capacity (safety rule)
Pound Tanks vs Gallon Tanks
📦 Pound Tanks (lb)
Portable cylinders rated by propane weight. A "100 lb tank" holds 100 lbs of propane (23.6 gallons). Common sizes: 20, 30, 40, 100 lb.
🏠 Gallon Tanks
Stationary tanks rated by volume. A "100 gallon tank" holds up to 80 gallons (80% fill = 339 lbs). Common sizes: 100, 250, 500, 1000 gallon.
The 80% Fill Rule
All propane tanks are filled to only 80% capacity. This isn't to cheat you—it's a critical safety measure. Propane expands approximately 1.5% for every 10°F increase in temperature. The 20% headspace prevents dangerous over-pressurization during hot weather.
💡 Did You Know?
A 100 gallon tank holds 3.4× more propane than a 100 lb tank
Propane doesn't expire - it can be stored indefinitely
Refilling saves 20-40% vs tank exchange programs
⚠️ Safety Tips
- Store tanks upright outdoors
- Check for leaks with soapy water
- Never store near ignition sources
- Transport in well-ventilated vehicle
- Requalify tanks every 5-12 years
Bookmark this page
Press Ctrl+D (⌘+D on Mac) for quick access next time.
Related Tools
Frequently Asked Questions
A 100 gallon propane tank holds approximately 424 pounds of propane when filled to the standard 80% capacity (80 gallons × 4.24 lbs/gallon = 339 lbs actual propane). The tank itself weighs about 215 lbs empty, so a full 100 gallon tank weighs approximately 555 pounds total. Note: Tanks are only filled to 80% to allow for thermal expansion.
A 100 lb propane tank holds approximately 23.6 gallons of propane. This is calculated by dividing 100 pounds by 4.24 lbs per gallon. The tank weighs about 70 lbs empty, so when full it weighs around 170 lbs total. These portable cylinders are commonly used for home heating backup, construction heaters, and large grills.
Filling a 100 lb propane tank typically costs $60-$100 depending on local propane prices ($2.50-$4.00 per gallon). At refill stations, you'll pay per gallon for the actual propane dispensed. Tank exchanges may cost more ($80-$120) but include inspection. Many hardware stores, propane dealers, and farm supply stores offer refills.
A 100 lb propane tank lasts approximately: 72 hours continuous on a 30,000 BTU heater, 18-20 days at 4 hours/day heating use, 70+ hours of BBQ grilling, or 4-5 months for a gas fireplace used occasionally. Usage varies based on appliance BTU rating and how often you use it.
Propane tanks are filled to only 80% capacity as a safety measure. Propane expands significantly with temperature changes - about 1.5% per 10°F increase. The 20% headspace allows room for this expansion, preventing dangerous over-pressurization. At 80% fill, a tank filled at 60°F won't exceed safe pressure even at 100°F+.
A 100 lb tank and 100 gallon tank are very different sizes. A 100 lb tank is a portable cylinder holding 23.6 gallons (100 lbs of propane). A 100 gallon tank is a larger stationary tank holding 80 gallons when filled to 80% (about 339 lbs of propane). The 100 gallon tank holds roughly 3.4× more propane than the 100 lb tank.
⛽ Disclaimer: These calculations are estimates based on standard propane properties at 60°F. Actual values may vary based on temperature, tank condition, and local regulations. Always consult with a licensed propane dealer for specific requirements.