If you put mid-grade gas in your car, it’s actually cheaper to pump in a mixture of premium and regular to get the same octane level. But how much of each do you use to get the right blend? As will some day be with all things in life, there’s an app for that.

The Gas Blend Calculator tells you how to get Mid-Range gas for less. Just enter in the 3 different octane ratings and their prices. Then say how much you want to spend or how many gallons you want to buy. Gas Blend does the math for you and tells ya.

It’s perfectly fine to combine different octane levels of gas, as long as they’re both unleaded. The only difference between the two blends is their octane content. It’s like if you had really sweet iced coffee and an only slightly sweetened batch of ice coffee and you wanted just a middle level of sweetness coffee and did it by making a blend of the two. It’s all the same coffee, only the sugar levels are different.

The app costs $1.99 but says you’ll make that back in just a couple trips to the gas station. Here’s how they break down the math:

Cost Savings Results
The Gas Blend calculates the exact number of gallons of Premium and Regular
to pump in order to get the same average octane as the posted 89 Mid-Grade:
– Pump 4.197 gallons of 93 octane-rated Premium gasoline
– Pump 8.395 gallons of 87 octane-rated Regular gasoline
– Total gallons pumped = 12.592 gallons

Proof of Two-Pump Method
4.197(93) + 8.395(87) = 12.592(89)
1,200.686 = 1,200.686
You pump twice and obtain the same number of gallons of the posted Mid-Grade gasoline. However, the cost of the Pump-Twice method is $36.00 which is less than the posted Mid-Grade cost of $36.88. Therefore, by using the Pump-Twice method, your cost of Mid-Grade gasoline has been cut by $0.88 on a 12.92 gallon purchase.

Here are the savings you would get for various number of gallons pumped:
Gallons Savings (compared to the posted Mid-Grade)
10 $0.70
12.582 0.88 (example above)
15 1.05
20 1.40
30 2.10
40 2.80

Most cars, except those whose engines are specially designed for premium gas, will do just fine with regular gas. But some engines are geared for mid-range. Also, some older engines that used to be fine with regular gas will start knocking unless the higher octane mid-range is poured in. In these days of high and rising gas prices, that’s where an app like this can come in handy, especially if you don’t feel like reverse engineering the math.

Gas Blend Calculator [GasBlend]

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