Choosing the right propane tank size for your generator is one of the most important decisions in your backup power planning. Too small and you run out of fuel in the middle of a post-hurricane outage. Too large and you've spent more than necessary on installation and a tank that sits mostly empty.
The right answer depends on four factors: your generator's kilowatt rating, your planned outage coverage duration, your property's available space, and whether you'll be enrolled in Tropigas scheduled deliveries.
The Simple Formula
⚡ Tank size needed = Generator consumption (gal/hr) x Hours of coverage needed / 0.90
The 0.90 factor accounts for the Puerto Rico standard that propane tanks are filled to 90% capacity. In summer, this is reduced to 80-85% depending on the municipality.
Example:
A 20 kW generator at 50% load consumes 2.6 gallons per hour.
For 7 days (168 hours) of coverage: 2.6 x 168 / 0.90 = 485 gallons needed.
Result: A 500-gallon tank (450 usable gallons) covers approximately 7.2 days of continuous operation at this consumption rate.
Tank Size Recommendations by Generator Size
| Generator Size | 3-Day Coverage | 7-Day Coverage | 14-Day Coverage |
|---|---|---|---|
| 7 kW | 72 gal → 120-gal tank | 168 gal → 250-gal tank | 336 gal → 500-gal tank |
| 10 kW | 120 gal → 250-gal tank | 280 gal → 500-gal tank | 560 gal → 1,000-gal tank |
| 13 kW | 136 gal → 250-gal tank | 317 gal → 500-gal tank | 635 gal → 1,000-gal tank |
| 16 kW | 168 gal → 250-gal tank | 392 gal → 500-gal tank | 784 gal → 1,000-gal tank |
| 20 kW | 208 gal → 250-gal tank | 485 gal → 1,000-gal tank | 971 gal → bulk |
| 30 kW | 304 gal → 500-gal tank | 709 gal → 1,000-gal tank | 1,419 gal → bulk |
All figures assume 50% load operation. For heavy-load households, add 20% to 30%.
The Scheduled Delivery Factor
If you enroll in Tropigas scheduled deliveries, you can choose a smaller tank than the maximum coverage calculation suggests. Tropigas delivers before you reach 30% capacity, effectively extending your practical fuel supply.
For most Puerto Rico homeowners with scheduled deliveries, a 500-gallon tank paired with a 10 to 20 kW generator provides reliable coverage through all but the most extreme extended outage scenarios.
- Without scheduled deliveries: Size your tank for maximum expected outage duration.
- With scheduled deliveries: Size your tank for 5 to 7 days and rely on Tropigas delivery for extended events.
Standard Propane Tank Sizes Available in Puerto Rico
| Tank Size | Usable Propane (90% Standard) | Typical Application |
|---|---|---|
| 120 gallons | 108 gallons | Small generator, stove only |
| 250 gallons | 225 gallons | 7-10 kW generator |
| 500 gallons | 450 gallons | 10-20 kW generator |
| 1,000 gallons | 900 gallons | 20-30 kW generator |
| 1,000+ gallons | Bulk | Commercial, industrial |
Tropigas installs all standard tank sizes across Puerto Rico, above-ground and underground. Call 787-641-8002 for a free tank sizing consultation specific to your generator and property.
Ing. Rodolfo Leo Quiñones
Operations, Sales and Export Manager , Tropigas / Tropigas SXM
Expert in propane energy systems, NFPA compliance, and industrial gas logistics in Puerto Rico and the Caribbean.
