free tool
is cheaper gas worth the drive?
compare the savings at the pump with the fuel cost of getting there. enter your prices, fill size, mpg, and extra driving distance to see whether the cheaper station actually saves money.
you'd save about $6.69 after the detour.
- price difference / gallon
- $0.25
- gross pump savings
- $7.50
- detour fuel used
- 0.25 gal
- detour fuel cost
- $0.81
- net savings
- $6.69
you could drive up to about 55.6 extra round-trip miles before the cheaper price stops saving money.
estimates based on the values you entered. real costs vary with conditions, traffic, and driving style.
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the same cheap gas isn't the same deal for every driver
a price sign shows one number to everyone who drives past. but that number is not the deal — the deal depends on how much fuel you're buying and how far you have to go to get it. two drivers can pass the exact same cheaper station and get opposite answers.
say a station down the road is $0.20/galcheaper, and reaching it adds some round-trip miles. here's the gross savings for two very different tanks at that same gap:
gross savings at $0.20/gal on 11 gallons
gross savings at $0.20/gal on 30 gallons
same station, same price gap — but the pickup saves nearly three times as much, so it can absorb a much longer detour and still come out ahead. the compact's smaller savings get eaten by even a short drive. that's why "cheapest price" and "cheapest fill" are not the same thing.
what each input actually changes
gallons being purchased
the biggest lever. savings scale directly with gallons, so a bigger fill turns a tiny per-gallon gap into real money and buys room for a longer drive.
fuel grade & price
the price you actually pay sets both the savings and the cost of the detour fuel. diesel, regular, and premium all behave the same way in the math — plug in the price you'll pay.
mpg
your real-world fuel economy decides how much fuel the detour burns. lower mpg makes every extra mile cost more, which shrinks the payoff of a marginal drive.
real road distance
use the actual added round-trip miles, not the straight-line distance. a station that looks close but sits across a highway with no U-turn can cost far more driving than it appears.
weather & operating conditions
cold weather, A/C load, and stop-and-go traffic lower real mpg. when that happens, enter your lower real-world mpg — the detour gets a little more expensive. more on that in summer vs. winter gas.
how to calculate gas savings
the whole thing is three short lines:
gross savings = (nearby price − cheaper price) × gallons
detour cost = (extra round-trip miles ÷ mpg) × price you pay
net savings = gross savings − detour cost − value of your time
if net savings is positive, the cheaper station is genuinely the cheaper fill. the calculator above also solves for the break-even distance — the point where net savings hits zero — so you know exactly how far is too far.
frequently asked questions
how far should i drive for cheaper gas?
only as far as the savings can cover. multiply the price gap per gallon by the gallons you're buying for gross savings, then compare it to the detour cost (extra round-trip miles ÷ mpg × the price you pay). the calculator shows a break-even distance — the most extra round-trip miles you can drive before the cheaper price stops saving money.
how much does 20 cents per gallon save?
it depends on how many gallons you buy — about $2.40 on a 12-gallon car fill, $6 on a 30-gallon pickup or rv fill, and $40 on a 200-gallon diesel fill. the same discount is worth far more on a big fill, which is why a large tank can justify a longer drive.
is driving farther for cheaper gas worth it?
it's worth it when your gross pump savings clearly beat the fuel and time cost of the extra driving. a small top-off leaves almost no room for a detour; a large fill leaves a lot. enter your numbers above to see the net savings and whether the drive comes out ahead.
how do i calculate gas savings?
gross savings = (nearby price − cheaper price) × gallons. detour cost = (extra round-trip miles ÷ mpg) × price you pay. net savings = gross savings − detour cost − the value of your time. if net savings is positive, the cheaper station is genuinely cheaper.
does mpg change whether cheaper gas is worth driving to?
yes. mpg is in the denominator of the detour cost, so a lower-mpg vehicle burns more fuel for the same extra miles, making a marginal detour less worthwhile. it's also why cold weather, which lowers real-world mpg, can tip a borderline drive from worth it to not worth it.
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