Buy vs Lease Calculator
Buying and leasing a car get compared on monthly payment alone more often than not, which hides most of what actually decides which one costs you less. This tool runs the full math — loan amortization, resale equity, the mileage penalty a lease can hit you with, and what your down payment would have earned if you'd invested it instead — and normalizes both options to a monthly effective cost so a 3-year lease and a 6-year ownership period are comparable on the same footing.
What are you trying to decide?
Methodology
How the cost comparison works
Each option's total cost over its own time horizon (your expected ownership period for buying, the lease term for leasing) is converted to a monthly effective cost — total cost divided by months. That's what makes comparing a 36-month lease to a 72-month purchase fair: you're comparing dollars-per-month, not two totals over different windows.
What's in the buy-side total
Down payment, sales tax, purchase fees, every loan payment made during your ownership period (calculated with standard amortization — principal and interest, month by month), insurance, maintenance, fuel, registration, and the opportunity cost of tying up your down payment instead of investing it — minus the resale value you're expected to get back at the end.
What's in the lease-side total
Capitalized cost reduction (your lease down payment), acquisition fee, every monthly lease payment, insurance, maintenance, fuel, registration, the same opportunity-cost treatment on your down payment, an excess-mileage charge if your expected driving exceeds the lease's annual allowance, and the disposition fee at lease end.
Assumptions that matter most
The biggest one is your expected resale value if you buy — nobody knows this exactly, which is why it carries a higher uncertainty weighting in your Decision Confidence than a contractual number like your APR does. The assumed annual return on money not spent (default 5%) also matters more the larger your down payment is.
What this calculator does not include
It doesn't model financing a lease buyout, doesn't account for state-specific lease tax treatment (which varies significantly), and assumes your loan is paid off within your stated ownership period. If you plan to keep a car well past its loan term or sell it before the loan is paid off, treat the result as an approximation.
How Miser Score works here
Miser Score weights five things: monthly effective cost (the biggest factor, by design), how much equity you'd build, flexibility (leasing makes it easier to change vehicles), reliability/maintenance risk (older owned vehicles carry more of it), and how well your expected mileage fits what you're comparing. Cost is compared against a fixed realistic range, not just against the other option — so a $10/month difference and a $1,000/month difference are treated as genuinely different, not collapsed into the same score gap.
How Decision Confidence works here
Decision Confidence is separate from Miser Score. It reflects how complete your inputs are, how much of the comparison rests on hard numbers (like your APR) versus estimates (like resale value), how sensitive the result is to small changes, and how much real-world use this specific scoring model has had. A close result with shaky resale assumptions should show lower confidence than a lopsided result built on contractual numbers — and it does.
Examples
Short-term ownership, high mileage
Someone planning to keep a car 3 years and drive 18,000 miles/year will often see leasing penalized by excess-mileage charges unless they negotiate a higher allowance up front — worth checking before assuming a lease is cheaper just because the monthly payment looks lower.
Long-term ownership, low financing rate
A buyer keeping a vehicle 7+ years with a low APR and a car that holds its value well typically sees buying pull ahead on pure cost, even after accounting for rising maintenance risk over time.
Large down payment, high assumed investment return
A large cash down payment isn't free — it has an opportunity cost. If you'd otherwise invest that money at a meaningfully high return, a smaller down payment (and financing more) can come out ahead once that's accounted for.
Frequently asked questions
Why does the same monthly cost difference sometimes matter more than other times?
Because the comparison also weighs equity, flexibility, reliability, and mileage fit — not just cost. A cost advantage can be offset (or reinforced) by those other factors depending on your specific numbers and priorities.
What if I don't know my exact resale value?
Give your best estimate. The tool applies a higher uncertainty weighting to that number specifically, which shows up as lower Decision Confidence rather than pretending the number is more solid than it is.
Does leasing always win if I drive under the mileage allowance?
Not necessarily — mileage fit is one of five weighted factors, not the whole decision. Financing terms, your down payment, and how long you'd actually keep a purchased vehicle usually matter more.
Can I compare a 3-year lease to a 7-year purchase?
Yes — that's specifically what the monthly-effective-cost normalization is for. Enter your actual expected ownership period for the buy option; it doesn't need to match the lease term.
What does 'too close to call' mean?
It means the calculated advantage is small enough, relative to the assumptions involved, that this tool won't manufacture false confidence in a winner. You'll still see both scores and the full breakdown — just not a forced recommendation.
This tool provides estimates for informational purposes and is not financial advice. Actual costs depend on your specific loan/lease terms, local taxes, and market conditions.