A 15-year mortgage usually carries a lower rate and far less total interest, but a higher monthly payment. A 30-year loan stretches payments and preserves monthly cash flow at the cost of more interest over time.
Run the numbers with the free mortgage calculator on ezcalcs, then come back to this guide for context. Results are estimates for planning only.
Compare the same principal and rate assumptions in the mortgage calculator for both terms, then weigh payment flexibility against lifetime interest.