Mortgage Calculators

MortgageLab guides

Plain-language answers to mortgage calculators questions, written from the same sourced data behind MortgageLab. Every guide lists its sources and the date it was last updated.

• Updated June 10, 2026

  When does PMI apply and what does it add to your monthly payment?

  PMI applies when your down payment is under 20%. On a $350,000 home with 5% down, a 0.80% PMI rate adds about $222 per month to your payment.

• Updated June 10, 2026

  How much more interest does a 30-year mortgage cost than a 15-year?

  On a $280,000 loan the 30-year term costs $228,483 more in total interest than a 15-year loan. See worked examples and the monthly payment trade-off.