The formula
How it works
Decide between a cash-back rebate and a low-interest deal on a car. Enter the price and both offers, and the calculator compares the monthly payment and total cost of each, then names the cheaper one.
FAQ
Why isn’t the bigger rebate always better?
A rebate lowers the amount you borrow, but it usually comes with a higher interest rate. A low-APR deal keeps the rate down but forgoes the rebate. Which wins depends on the size of the rebate, the gap between the rates and the loan term — so it has to be worked out, not guessed.
Does the loan term change the answer?
Yes. The longer the term, the more the interest rate matters relative to the one-off rebate, because you pay interest for longer. On a short loan the rebate often wins; on a long loan the low rate tends to. Try different terms to see where the crossover is.
Can I combine the cash-back rebate with the low-APR offer?
Almost never — dealers and lenders set these up as separate, mutually exclusive incentives, so you pick one path or the other. That is exactly why this calculator compares them side by side rather than assuming you can stack both.
Does my credit score affect which deal is better?
Indirectly, yes. The advertised low APR usually requires strong credit, so if your score falls short you may only qualify for a higher rate, which can tip the comparison toward the rebate. Enter the actual rate you are offered rather than the advertised one for an accurate result.
Does a bigger down payment change which option wins?
It shrinks both loans by the same amount, which narrows the gap between the two total costs and the two monthly payments. It rarely flips the winner outright, but it does reduce how much the better choice saves you.
Is the cash-back rebate taxed or does it reduce the taxable price?
That depends on your state or country — in many places sales tax is calculated on the price before the rebate is applied, so the rebate does not lower your tax bill even though it lowers what you finance. Check local rules, since this calculator focuses on financing cost, not tax treatment.
What if the two total costs come out almost equal?
When the gap is small, other factors — like wanting a lower monthly payment for cash-flow reasons, or avoiding a longer commitment at a given rate — can reasonably break the tie. Use the monthly payment figures alongside the total cost to decide what fits your budget best.
About the cash back or low interest calculator
Car dealers often let you choose between a cash-back rebate and a low or zero interest rate, and the two are surprisingly hard to compare in your head. This calculator does it properly: it works out the monthly payment and total cost of each offer over the same loan and tells you which leaves you paying less overall. It turns a common showroom dilemma into a clear number.
How to use it
Enter the vehicle price, your down payment and the loan term, then the cash-back amount with its interest rate, and the low interest rate offered instead. The calculator shows the monthly payment and total cost for each path and the amount you save by choosing the better one. For example, a $2,000 rebate at 6% often beats a 1% loan on a short term, but the low rate can win over five or six years.
The formula
Each option is a standard car loan. The cash-back path borrows the price minus the down payment minus the rebate at the higher rate; the low-interest path borrows the price minus the down payment at the lower rate. Both use the amortization payment , and the total cost is . The calculator compares those totals.
Where it is used
Car buyers use it at the point of financing, when a dealer presents both incentives and asks which they want. It is equally useful for planning ahead — deciding what rebate would be needed to beat a promotional rate, or how the choice shifts with a bigger down payment or a different term. Because it compares total cost, it cuts through marketing framing to the real price.