This simple formula can tell if you’re getting ripped off by an airline

Travelers no longer have to guess whether they got a decent deal on airfare or not.

There’s now a straightforward formula that can reveal whether those plane tickets are a good deal — or something to skip, according to software and cloud computing company Adobe ADBE, +0.62%  , which analyzed billions of transactions booked with seven major airlines from 2014 to 2016.

Here’s the formula for determining whether the cost of a your domestic roundtrip flight is a good deal: Multiply the number of roundtrip miles on the trip by $0.032, then add $230.

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For example, let’s say you’re flying from New York to Los Angeles, which is 5,640 miles roundtrip. Multiply 5,640 x .032 and then add $230 to get a total of $410.48. This means that, in general, roundtrip flights between New York and Los Angeles below $410, including taxes and fees, are decent deals (or put more simply, that they’re cheaper that the majority of the flights that have been sold over the past couple of years).

For international flights, the formula is slightly different: Multiply the round-trip miles by $.08 and then add $200. So, a roundtrip ticket from New York to London that costs less than $750 is a decent deal.

Use this calculator to see if your plane ticket is a good deal

My flight is domestic international

ROUNDTRIP MILES*

miles

*Check your ticket for miles.

Note: Results are calculated using the following formula from Adobe, which analyzed billions of transactions booked with seven major airlines from 2014 - 2016. For domestic flights, multiply the number of roundtrip miles on your trip by $0.032, then add $230. For international flights, multiply the round-trip miles by $.08 and then add $200.

The formula was calculated based on the strong correlation between a flight’s “fixed” price and the number of miles traveled on a round-trip flight. A more complete explanation of the methodology can be found here.

One caveat: These formulas by no means give the lowest price available for flights right now -- only whether the quoted price is relatively lower or higher than prices for that route have been in the past couple of years. And while that won’t be useful for everyone, it is for the consumer who can’t comparison shop for flights for weeks, and simply wants to know whether the deal they’re getting is at least decent.

Consumers who are pressed for time can do other things to save money, even without doing a bunch of comparison shopping.

First, time it right: While the cheapest travel days do depend on the route, in general, Tuesday and Wednesday are the least expensive days to fly on because demand is lowest, says Patrick Surry, the chief data scientist at airfare research siteHopper.com. Furthermore, while airfares rise in early summer, they begin to fall towards the end of summer, particularly for international flights, says Surry.

Second, the ideal time to book most flights (other than for some holidays like Labor Day, Memorial Day and the Fourth of July) for deals is roughly 90 days out, the Adobe data reveal. “Booking more than three to six months ahead can cost you since airlines set their initial prices conservatively,” says Surrey.