How much house can I afford with $100k down?

The practical answer

With $100,000 saved for a down payment, the arithmetic ceiling is simple: $1,000,000 of home at 10% down, or $500,000 at 20% down. But in practice the monthly payment usually binds first — what income supports matters as much as what savings allow.

A worked example: a household earning $180,000 with $130,000 in total investable assets (keeping $30,000 as a cushion, so about $100k deployable), on a 30-year fixed at 6.75%, models out to roughly a $770,000–$810,000 home at 11–13% down with a payment near $5,100/month including property tax. Pushing to the full $1M ceiling would require both PMI and a payment most $180k households would find uncomfortable.

• Putting less than 20% down means PMI — often 0.3–1% of the loan per year until you reach 20% equity.
• Deploying every dollar of savings into the down payment leaves no cushion for repairs, job changes, or closing surprises.
• A $100k down payment goes dramatically further in a 1% property-tax county than a 2% one — the tax difference compounds against the payment ceiling.
• If family gift funds are part of the picture, model them separately — lenders treat documented gifts differently from your own savings.

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