Most people are shown one number at a dealership: the monthly payment. That number is the end of a calculation, not the start of one, and the calculation is not complicated. Once you can run it yourself, you can tell the difference between a genuinely good deal and a payment that was lowered by moving money somewhere you did not look.

If you are new to leasing entirely, start with how car leasing works and come back here for the arithmetic.

The formula

A lease payment is two charges added together:

Depreciation charge. The value the car loses while you have it, spread across your term.

Finance charge. What the lender earns for putting up the money in the meantime.

Written out:

  • Depreciation charge = (adjusted cap cost - residual value) / term in months
  • Finance charge = (adjusted cap cost + residual value) x money factor
  • Monthly payment = depreciation charge + finance charge

That is the whole thing. Four inputs: adjusted cap cost, residual value, money factor, and term.

A worked example

Say a car has a $38,000 MSRP. You negotiate the selling price to $35,500. Residual is set at 58% for 36 months, and the money factor is 0.00150.

  • Residual value = $38,000 x 0.58 = $22,040
  • Adjusted cap cost = $35,500
  • Depreciation charge = ($35,500 - $22,040) / 36 = $373.89
  • Finance charge = ($35,500 + $22,040) x 0.00150 = $86.31
  • Monthly payment = $460.20, before tax

Now change one input and watch what happens. Negotiate the selling price down by $1,500 to $34,000:

  • Depreciation charge = ($34,000 - $22,040) / 36 = $332.22
  • Finance charge = ($34,000 + $22,040) x 0.00150 = $84.06
  • New payment = $416.28

A $1,500 price reduction took $44 off the monthly payment. That is why the selling price is worth negotiating even though nobody at the dealership is talking about it.

Why the residual does so much work

Notice that residual value shows up twice, and it pulls in opposite directions. A higher residual means less depreciation to pay for, which lowers your payment. It also means a bigger number inside the finance charge, which raises it slightly. The depreciation effect is much larger, so a high residual is almost always good news for a lease.

This is why two cars with identical prices can lease for very different amounts. A model that holds its value leases cheaply. A model that drops hard is expensive to lease even when it is cheap to buy. It also explains a thing that surprises people: a more expensive car sometimes leases for less than a cheaper one.

The residual is set by the lender or the manufacturer. It is not negotiable, which makes it the one input you have to shop for rather than argue about.

What you can actually change

Of the four inputs, two are yours to move and two are not.

You can change the adjusted cap cost. This is the selling price plus fees, minus any rebates and down payment. Negotiating the selling price is the single most effective thing you can do.

You can change the term and mileage. Both shift the residual. A shorter term usually means a higher residual percentage. A lower mileage allowance does too, because the car is worth more at the end.

You cannot change the residual percentage for a given term and mileage. It is published by the lender.

You cannot usually change the money factor, though your credit tier decides which one you qualify for. Moving up a tier is worth real money, which is why it can pay to work on your credit before you sign.

Where the number gets manipulated

Every one of these levers can be used to make a payment look better than the deal is.

Money down. Putting cash down lowers the adjusted cap cost, which lowers the payment. It does not make the lease cheaper. You paid the money either way, just earlier. Worse, if the car is totalled in month three, that cash is usually gone. This is covered fully in how much to put down on a lease.

A longer term. Stretching 36 months to 48 spreads depreciation over more payments. The monthly number drops and the total cost rises, and you spend the last year outside the factory warranty.

A lower mileage allowance. Advertising a payment at 7,500 miles a year makes it look cheap. If you drive 12,000, you will pay the difference at the end at 15 to 30 cents a mile.

Fees rolled into the cap cost. An acquisition fee financed rather than paid up front quietly raises both charges. See every fee on a lease.

None of these is dishonest by itself. They only become a problem when the payment is presented without them.

The one question that cuts through it

Ask for the four inputs: selling price, residual, money factor, and term, plus the mileage allowance. Any lender or broker who is comfortable with the deal will give you all five without a fuss.

If someone will only discuss the monthly payment, that is worth noticing. The payment is the output. You want the inputs.

Where a broker fits

This is most of what we do. We take your target car and put it in front of multiple lenders and dealers, then compare the four inputs side by side rather than the advertised payment. A car with a worse selling price and a much better residual often wins, and you cannot see that from a payment alone.

If you want the numbers on something specific, tell us the car and we will bring back the figures broken out this way.