With gasoline prices in the US up 33% over last year and US airfare and rising 15% to 20%, many travellers in the United States are grappling with the decision to drive or fly on their next trip.

On BBC Travel’s Facebook page, 49% of poll respondents said given recent spikes in airfare, they would ditch the airport for the open road. Another 15% said driving takes too long, and 37% said it depends; with the price of gas, road trips may cost more.

Jon Lal faced that same decision when his family of four wanted to travel from Boston to Myrtle Beach, South Carolina for a summer vacation. Lal is the founder of BeFrugal.com, a two-year-old website that helps consumers save money by providing access to coupons, deals and promotional codes found online.

“If we were going somewhere two or three hours away by car, the decision would be easy, we’d drive,” Lal said. “If we’d decided to go somewhere a lot farther away, like California, the decision would be easy, too. We’d fly instead of taking five days to drive across the US.”

But deciding how to travel to Myrtle Beach, located about 880 miles away, takes some serious calculating. Door-to-door driving time would be about 16 hours each way. Door-to-door flying time (including ground transfers) would be about six hours.

“It’s those in-between distances in that gray area between really far away and really close that make it hard to decide,” Lal said.

That’s when Lal’s background in computer programming came in handy. “There are a variety of factors and lots of tradeoffs that can get overwhelming when trying to decide whether to drive or fly. So we decided to wrap some math around the process and we came up with the Fly or Drive Calculator,” he recalled.

The easy-to-use calculator asks for a starting location and destination, and the number of travellers. Then it asks for type of vehicle, how many hours a day you expect to drive and estimated nightly hotel costs.

For the flying side of the equation, it asks for origin and destination airports, estimated check-in time and the estimated ground transportation costs to and from the airport on both ends of the journey. The site conveniently pre-populates fields with estimated airfare and checked bag fees.

In Lal’s case, estimated airfares between Boston and Charleston (near Myrtle Beach) were $321, plus checked bag fees of $25. But the biggest cost was transportation from the airport in Charleston to their resort in Myrtle Beach — nearly $300.

The total cost for flying his family of four from Boston to Myrtle Beach for a summer vacation would have been about $2,200. Total cost for driving? About $660. Lal chose the latter, saving about $1,500.

Would he have made the same decision if it were a business trip? Probably not.

“For business travellers, time is much more important than it is for vacationers. Plus, business travellers usually travel alone, which makes airfare cheaper and driving more expensive because you can’t spread the cost over three or four travellers,” Lal said. “From Boston, I’d probably drive the two or three hours for a business trip in the northern reaches of New York City. Any further than that? I’d fly.”

How do you make the decision to drive or fly? Would you use a calculator like this to help decide? Please leave your comments on our Facebook page.

Chris McGinnis is the business travel columnist for BBC Travel