Car Lease vs Buy Calculator Formula

Understand the math behind the car lease vs buy calculator. Each variable explained with a worked example.

Formulas Used

Total Lease Cost

lease_total = lease_monthly * term_months

Buy Cost (minus equity)

buy_total_minus_equity = loan_monthly * term_months - car_price * residual_pct / 100

Equity After Buying

equity_at_end = car_price * residual_pct / 100

Variables

VariableDescriptionDefault
car_priceVehicle Price(USD)35000
lease_monthlyMonthly Lease Payment(USD)350
loan_monthlyMonthly Loan Payment(USD)600
term_monthsTerm Length(months)36
residual_pctResidual Value After Term(%)55

How It Works

Leasing vs Buying a Car

Leasing has lower monthly payments but builds no equity. Buying costs more monthly but you own an asset at the end.

Comparison

Total Lease Cost = Monthly Payment x Term Months (you own nothing at the end)

Net Buy Cost = Total Payments - Residual Value (you keep the car)

The true comparison is total lease outflow vs (total loan payments minus the car's remaining value). If the car retains value well, buying usually wins long-term.

Worked Example

$35,000 car, $350/mo lease vs $600/mo loan, 36-month term, 55% residual.

car_price = 35000lease_monthly = 350loan_monthly = 600term_months = 36residual_pct = 55
  1. 01Total lease = $350 x 36 = $12,600 (nothing to show for it)
  2. 02Total loan payments = $600 x 36 = $21,600
  3. 03Car value at end = $35,000 x 55% = $19,250
  4. 04Net buy cost = $21,600 - $19,250 = $2,350
  5. 05Buying costs $10,250 less when accounting for equity

Ready to run the numbers?

Open Car Lease vs Buy Calculator