Choosing the right propane tank size is less about maximum capacity and more about how often you want to think about refills. For rural homes and cottages, tank size directly affects delivery frequency, winter reliability, and the risk of running low during peak demand.
This article explains common propane tank sizes used in Canada, how refill timing works, and how backup generators change consumption patterns. The goal is to make refill planning predictable rather than reactive.
How propane tank sizing actually works
Propane tanks are described by their water capacity, not the amount of propane they can safely hold. For safety reasons, tanks are typically filled to about 80 percent of their rated capacity, leaving room for expansion.
That usable capacity is what matters when estimating how long a tank will last between deliveries.
Refill timing depends on three variables:
- Tank size and usable volume
- Average daily propane consumption
- The refill threshold you are comfortable with, often 20 to 30 percent remaining
Common residential propane tank sizes in Canada
The following table shows commonly used residential tank sizes, their typical usable propane volume, and how often they are usually refilled for a primary residence without a generator.
These are general planning estimates. Actual refill frequency varies by climate, home size, insulation, and appliance mix.
Typical usage: full-time residence, space heating and hot water
| Tank size (rated) | Usable propane (approx.) | Typical refill frequency per year |
|---|---|---|
| 420 lb (120 gal) | ~380 litres | 5–7 fills |
| 500 gal | ~1,500 litres | 3–4 fills |
| 1,000 gal | ~3,000 litres | 2–3 fills |
Smaller tanks are common for light usage or seasonal properties but require more frequent deliveries, particularly in winter, where cold-weather demand and refill thresholds shorten the effective interval between fills.
How refill timing is estimated
To estimate days-to-empty, start with usable propane volume and divide by average daily usage.
For example:
- A 500-gallon tank has roughly 1,500 litres of usable propane
- If average winter usage is 15 litres per day
- The tank provides roughly 100 days of supply
Most homeowners do not plan to reach empty. Refills are usually scheduled when the tank reaches 20 to 30 percent remaining, reducing the practical interval between deliveries.
Seasonal usage patterns matter
Propane consumption is rarely uniform throughout the year.
Typical patterns include:
- High usage during cold winter months
- Moderate usage in shoulder seasons
- Minimal usage in summer if propane is used mainly for hot water or cooking
For cottages, usage can be highly irregular. A property may consume very little propane for weeks, followed by heavy usage during short winter stays or holiday periods.
This variability is one reason larger tanks are often preferred for seasonal properties.
How backup generators change tank sizing
Backup generators can significantly affect propane consumption, particularly during extended power outages.
Generator fuel use depends on:
- Generator size and load
- Duration of outages
- Whether the generator powers essential loads or the entire home
Even moderate generators can consume propane quickly during continuous operation.
Estimated refill frequency with a backup generator
The table below shows how refill frequency can change when a backup generator is connected, assuming several multi-day outages per year.
These figures are illustrative and assume the generator runs only during outages, not continuously.
| Tank size (rated) | Typical refills per year (no generator) | Typical refills per year (with generator) |
|---|---|---|
| 420 lb (120 gal) | 5–7 | 7–9 |
| 500 gal | 3–4 | 4–5 |
| 1,000 gal | 2–3 | 3–4 |
For properties where generators are critical, larger tanks reduce the risk of running low during extended outages or severe weather.
Refill thresholds and safety margins
Most suppliers recommend refilling before the tank drops below 20 percent. Waiting longer increases the risk of:
- Running out during delivery delays
- Pressure issues in extreme cold
- Emergency delivery fees
Larger tanks provide a wider safety margin, which is especially valuable for properties with limited winter access.
Automatic delivery versus will-call
Tank size also interacts with delivery scheduling.
With automatic delivery:
- Suppliers estimate usage and schedule refills proactively
- Larger tanks provide more buffer if estimates are off
With will-call delivery:
- Homeowners monitor tank levels themselves
- Larger tanks reduce the risk of forgetting to schedule a refill in time
For cottages that are vacant for long periods, will-call with a larger tank is common, but it requires disciplined monitoring.
Choosing a tank size for rural homes and cottages
In rural and seasonal settings, tank sizing is less about minimising upfront cost and more about reducing delivery pressure and winter risk.
Larger tanks:
- Reduce refill frequency
- Improve resilience during cold snaps and outages
- Make seasonal planning easier
Smaller tanks:
- Take up less space
- May be suitable for light or summer-only usage
- Require closer attention to refill timing
Planning refill timing reduces surprises
Propane tank sizing and refill timing are closely linked. Understanding usable capacity, seasonal consumption, and the impact of generators makes refill planning straightforward rather than reactive.
For rural homes and cottages in particular, choosing an appropriate tank size and conservative refill threshold is one of the simplest ways to reduce emergency deliveries and winter stress.