How to use the gas station rewards value calculator
- Enter the reward per gallon in cents, for example 10 for ten cents off each gallon. The starting value is an example.
- Enter the gallons pumped on the fill up and the pump price per gallon you see.
- If your program stops the discount after a number of gallons, enter that number under Most gallons that earn the reward. Leave it blank for no cap.
- Open Advanced options to change the fill ups a month. Read the dollars saved, the cost after the reward and the monthly and yearly total. Use Copy, Print or CSV to keep it.
Formula
Gallons that earn the reward = smaller of gallons pumped and the cap (all gallons if no cap)
Savings = cents per gallon / 100 x gallons that earn the reward
Cost after = gallons x pump price - savings
Effective price per gallon = cost after / gallons pumped
Monthly and yearly savings multiply one fill up by the fill ups you enter, so they assume the same size each time.
Ten cents off 12 gallons
Pumping 12 gallons at $3.50 costs $42.00. A reward of 10 cents a gallon saves 0.10 x 12 = $1.20, so you pay $40.80. The effective price is $40.80 / 12 = $3.40 per gallon, or 2.86% less than the pump price.
With four fill ups of that size a month, the reward is worth $4.80 a month and $57.60 a year. If the program caps the discount at 10 gallons, the saving on this fill up falls to $1.00 and the note under the headline shows that the gallons were capped from 12.
What the reward is really worth
A cents off per gallon reward sounds big but is small per visit, and the value depends on how much you pump. Because the discount is per gallon, a truck that holds 25 gallons saves more per fill up than a small car, though not necessarily more per mile. Looking at a month or a year shows whether a program is worth the effort or any extra spending it encourages.
Rewards often come with conditions such as buying groceries to earn points, a cap on gallons or a time limit. This tool values the reward once you know it. It does not predict how many points you will earn, and it should not be the only reason to choose a station if the pump price there is higher.
Comparing stations
To compare two stations fairly, compare the effective price per gallon, not the discount. A station with a 10 cent reward and a higher pump price can cost more than a plain station that is 10 cents cheaper. Run each through the tool, then compare the effective price rows.
For the cost of a whole trip, use the fuel cost calculator, and to understand your mileage use the MPG calculator. Rewards on a card are a different kind of benefit, which the credit card rewards calculator can value. The distance on a tank calculator shows how far a fill up takes you.
Assumptions and limits
- The pump price and the reward are the figures you enter. The starting $3.50 and 10 cents are examples, not current prices.
- Savings are calculated on the gallons that earn the reward. Sales tax and fees at the station are not modeled.
- Monthly and yearly savings assume the same fill up each time.
- Points programs that pay in points or percentages of spending are not modeled.
Frequently asked questions
How do I calculate the savings from cents off per gallon?
Convert the cents to dollars and multiply by the gallons. Ten cents off 12 gallons is 0.10 x 12 = $1.20.
What is the effective price per gallon?
It is the total you pay after the reward divided by the gallons pumped. It lets you compare a discounted price with a station that simply has a lower pump price.
What if my program has a gallon limit?
Enter the limit in the cap field. The tool applies the reward to the smaller of the cap and the gallons you pump.
Why does the tool refuse a very large reward?
If the reward is more than the cost of the fuel, the numbers are almost certainly a typing slip, such as entering dollars where cents were expected. The message points to the field to check.