Deshone the Auto Advisor spent a decade selling cars at dealerships. According to his website, now he teaches people how to save thousands on car shopping without anxiously wasting time in sales departments. This week, he shared about what he believes is the worst thing you can do at a car dealership: show up not knowing how to estimate your car payment. Deshone says he spent five years with Mercedes-Benz and another five years with GM. He has two quick tips for figuring out if you’re getting a good lease payment quote or whether your financed car payment is above or below average.

Deshone reports he’s been involved with thousands of lease deals. If you’re looking to lease a car, he recommends using the multiplier .015. That’s 1.5%. Get a quote for a first lease payment when driving 12,000 miles per year. Then, take the estimated value of the car. For this example, he uses $35,000. $35,000 times .015 is $525. If the estimated car payment quote is above 1.5% of the value of the car, he says that’s a bad lease deal.“Shop around or buy something else.”

In terms of calculating your financed car payment, Deshone has a simple rule of thumb. “Every $5,000 bucks is a hundred bucks a month.” So, if you’re looking at financing a $15,000 car, that should land around $300 per month. A $50,000 car would be around $1,000 per month. “Know these numbers before you go,” he advises.

While these aren’t hard rules, and individual financing will depend on a variety of factors, his tips can be helpful. If anything, Deshone gives us an idea of where an insider expects car payment quotes to fall in 2024.