10% vs 20% Down Payment Calculator
The extra 10% is real money. See what it actually buys — in monthly payment, in PMI, and in lifetime interest — and what happens if you buy now with 10% and pay the rest in two years later instead.
How to Use This Down Payment Calculator
Three versions of the same $375,000 purchase at 6.75% over 30 years are preloaded below: 10% down, 20% down, and 10% down with the remaining $37,500 paid into the loan at the start of year three. The house, rate, term, taxes and insurance are identical in all three, so every difference you see comes from the down payment alone.
What to look at:
- 1.Total Monthly Payment - the 10% scenarios carry a permanently higher required payment, which is the cost of the smaller down payment
- 2.PMI Ends - month 98 at 10% down, month 25 if you pay the difference in at year three, never applicable at 20%
- 3.Total Interest - the headline saving from a larger down payment, which you should weigh against what the cash would earn elsewhere
- 4.Switch to "Edit Individual Scenario" to use your own price, quoted rates, and PMI rate — pricing at 90% and 80% loan-to-value is rarely identical
What the extra 10% actually buys
The same $375,000 home at 6.75% over 30 years. The difference between 10% and 20% down is $37,500 — the third scenario keeps that money for two years and then pays it straight into the loan, so you can see what the timing is worth on its own.
The catch, stated up front: a smaller down payment sets a permanently higher required payment. Scenarios 1 and 3 owe $2,189 a month in principal and interest against $1,946 for 20% down, because the payment is fixed on the balance at closing and a later lump sum does not re-amortise it. The table below shows the full PITI figure, which adds PMI on top of that gap until it cancels. The third scenario is not free — it trades the higher payment for two years of liquidity.
Tip: Switch to "Edit Individual Scenario" to use your own price, PMI rate, and timing.
Reading the Comparison Honestly
The deferred scenario is not a free lunch
Putting 10% down and paying the rest in later finishes ahead on total interest, but it commits you to the higher required payment for the whole life of the loan. A lump sum reduces the balance without re-amortizing the payment, so the monthly obligation stays at the 10%-down level even after the money goes in. That is a genuine cash flow cost, and it is the reason this option is not strictly better.
PMI is temporary, the balance is not
PMI is the most visible cost of a smaller down payment and the one that ends. The larger balance is the one that lasts thirty years. When people compare down payments they tend to focus on the PMI line because it has a name and a monthly figure, but on this loan the additional interest from the bigger balance is several times the PMI.
What the calculator cannot price
Three things sit outside this model and often dominate the decision: what the same cash would return if invested instead, what the house costs if you wait two years to buy it, and what you pay in rent while saving. The interest and PMI figures here are exact. Treat them as one input to the decision rather than the decision.
Frequently Asked Questions
Is a 20% down payment worth it?
It buys three things: no PMI, a smaller balance, and usually a slightly better rate. Against that, it commits a large amount of cash to an illiquid asset and can delay the purchase by years. The comparison above quantifies the first half — on a $375,000 home the extra $37,500 saves roughly $61,000 in interest and PMI over thirty years. Whether that beats what the same money would do elsewhere, and whether waiting to save it is worth the rent and price movement in between, is the part no calculator can settle.
What happens if I put 10% down instead of 20%?
Your loan is $37,500 larger on this example, your required monthly payment rises by about $243, and you pay PMI until the balance reaches 80% of the original purchase price — around month 98 without extra payments. The rate you are offered may also be slightly higher, since conventional pricing improves as loan-to-value falls. None of these are permanent except the larger balance: PMI ends, and the payment gap narrows in real terms over thirty years.
Can I avoid PMI without putting 20% down?
Sometimes. Lender-paid PMI folds the cost into a higher interest rate, which never cancels but is tax-treated differently and can be cheaper if you move within a few years. Piggyback structures split the borrowing into a first and second lien to keep the first at 80%. Some credit unions and portfolio lenders waive PMI for particular professions or for strong credit profiles. All of these trade the explicit PMI line for a cost somewhere else, so compare the total rather than the label.
Should I wait and save 20%, or buy now with 10%?
The calculator answers half of it: the third scenario buys now with 10% down and pays the other $37,500 in two years later, which ends PMI at month 25 rather than month 98 while keeping the cash available in the meantime. What it cannot tell you is what the house costs in two years, or what you pay in rent while saving. In a rising market waiting often costs more than PMI does; in a flat one it rarely does.
Does a bigger down payment get you a lower interest rate?
On conventional loans, generally yes. Loan-level price adjustments are priced off loan-to-value and credit score, so a 20% down borrower usually sees a better rate than an otherwise identical 10% down borrower — often somewhere between an eighth and a half of a point. The scenarios above deliberately hold the rate constant so that the down payment is the only variable; add your own quoted rates in the editor to see the combined effect.
How much is PMI on a 10% down payment?
At 90% loan-to-value, mid-tier conventional PMI is commonly around 0.4% of the loan a year, which is roughly $113 a month on the $337,500 loan modelled here. Pricing varies substantially with credit score, and rises sharply at 95% loan-to-value. PMI cancels on request once the balance reaches 80% of the original purchase price and automatically at 78%, so it is a temporary cost with a knowable end date rather than a permanent one.