Down Payment Calculator
Calculate the down payment on a home, the resulting loan amount, and the monthly payment that follows.
Formula and sources updated · Data sources · 1View algorithm, constants and default inputs (JSON)
About this calculator
Estimate the down payment and monthly principal-and-interest payment from the entered price, rate, and term. The monthly figure excludes property taxes, homeowners insurance, mortgage insurance, HOA dues, closing costs, and lender fees. Mortgage-insurance requirements vary by loan and lender.
Worked example
calculated with the default values below
Home price 400,000 $ · Down payment 20 % · Mortgage interest rate 6.5 % · Loan term 30 years Down payment 80,000.00 $ · Loan amount 320,000.00 $ · Monthly principal and interest (estimate) 2,022.62 $ · Total interest 408,142.36 $
Method and assumptions
Formula basis and scope
Fixed monthly payment = P × i / (1 - (1 + i)^(-n)); i is annual percent / 1200. At zero interest, payment = P / n. P is home price minus the percentage down payment.
Fixed nominal rate and monthly payments; fees, insurance, taxes and lender-specific daily accrual are excluded. Fractional month counts are mathematical projections, not an actual payment schedule.
Data sources
Disclaimer
These calculators give estimates for general information only. They are not financial, tax or investment advice and do not take your personal circumstances into account. Before borrowing, investing or filing, confirm the numbers with a qualified adviser in your jurisdiction.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
L = P × (1 − d ÷ 100); M = L × r × (1+r)^n ÷ ((1+r)^n − 1); I = M × n − L
- P
- home price
- d
- down payment, %
- L
- loan amount
- r
- monthly interest rate
- n
- number of months
- M
- monthly payment
- I
- total interest
r = annual rate ÷100÷12 and n = years×12. If r = 0 the payment is L÷n; I is the total interest over the full term.
Frequently asked questions
What should I know about this estimate?
Estimate the down payment and monthly principal-and-interest payment from the entered price, rate, and term. The monthly figure excludes property taxes, homeowners insurance, mortgage insurance, HOA dues, closing costs, and lender fees. Mortgage-insurance requirements vary by loan and lender.