Down Payment Calculator
Calculate a required down payment from purchase price and your chosen percentage, then estimate how long it may take to reach that savings goal under an APY and monthly contribution assumption. The percentage is a savings goal you select — not a lender requirement, PMI rule, or guarantee of mortgage qualification.
Your results will appear here
Enter your assumptions and calculate to see the estimated result and supporting details.
How this calculator works
Enter purchase price, desired down-payment percentage, current savings, monthly contribution, and APY.
Required down payment = price × percentage. Time to goal uses the same effective-APY, end-of-month deposit convention as Savings Goal — Time Required, capped at 100 years.
Formula / methodology
target = purchasePrice × downPaymentPercent rm = (1 + APY)^(1/12) − 1 balance_m = balance_(m−1) × (1 + rm) + monthlyContribution
- APY is an effective annual yield assumption you supply.
- Interest is applied before the end-of-month deposit; then the target is checked.
- Identical inputs produce the same timing results as Savings Goal time-required mode.
Worked example
$400,000 purchase price, 20% desired down payment, $20,000 current savings, $1,000 monthly, 5% APY.
Required down payment = $80,000. Estimated time ≈ 51 months. Balance when first reached ≈ $81,166; estimated interest ≈ $10,166.
Important assumptions
- Desired down-payment percentage is a user-selected savings goal.
- APY is not inferred from current bank rates.
- PMI, closing costs, and underwriting rules are not modeled.
- Search horizon matches Savings Goal (1,200 months).
Common questions
Not by this calculator. Enter any percentage from 0% to 100% as your savings goal. Lender requirements vary and are not modeled here.
This tool does not evaluate mortgage qualification. It only estimates a savings goal and time to reach it under your assumptions.