Calculators

Where the defaults come from

Rate defaults come from the Freddie Mac Primary Mortgage Market Survey (PMMS). Appreciation defaults come from the FHFA House Price Index. Tax, insurance, and maintenance figures are labeled rules of thumb — override them with your local numbers whenever you have them. Full methodology.

Two terms, two very different totals

The term you pick changes the payment shape more than any other single choice. A 30-year loan spreads the same balance over 360 payments, so the monthly is lower and the interest total is higher; a 15-year loan compresses it into 180 payments — a bigger monthly, a much smaller lifetime total. On the calculator’s cited default rate (7.03%, the Freddie Mac PMMS average for the week ending September 24, 2026) and a $400,000 loan, the comparison looks like this: the 30-year runs about $2,669/month with roughly $560,900 of interest across the term; the 15-year runs about $3,602/month with roughly $248,400 of interest. Same house, same rate — the 15-year pays about $933 more per month and saves about $312,500 in interest.

The honest read: that trade isn’t “15-year wins.” It’s a tradeoff between monthly breathing room and lifetime cost, and the right answer depends on whether the higher payment stays comfortable through a job change, a repair year, or a rate environment you didn’t plan for. The amortization calculator renders both schedules side by side so the crossover is visible, not asserted — every figure is formula output from the cited defaults, never an estimate.

Run both terms side by side →

The biweekly shortcut, in one line of math

Biweekly payments are the simplest acceleration trick in mortgage math, and the arithmetic fits in one sentence: 26 half-payments a year equal 13 full payments. You pay half the monthly amount every two weeks; because there are 26 two-week periods but only 12 months, you make one extra full payment’s worth each year — the equivalent of adding one-twelfth of your monthly payment to each month. On the calculator’s default ($400,000 at 7.03%, 30-year), the monthly payment is $2,669.27, so the biweekly equivalent adds $222.44/month of extra principal — and that one extra payment per year pays the loan off in about 285 months instead of 360, saving roughly $137,800 in interest.

The honest mechanics: the result comes entirely from paying 13 payments a year, so any method that gets 13 payments in produces the same schedule — a servicer-run biweekly program, or simply adding the $222.44 yourself each month. What matters is that the extra reaches principal immediately; a wrapper that holds your money between debits is charging you for the same math you can run for free. The payoff calculator models both month by month.

Model the extra payment on your loan →

Discount points: prepaid interest, priced in months

A discount point is prepaid interest: one point costs 1% of the loan amount and buys a lower rate. On a $400,000 loan, one point costs $4,000. Whether that’s worth it depends on a single number most rate-shopping skips — the breakeven: total points cost divided by the monthly payment savings. Illustratively, at the calculator’s cited default rate (7.03%, PMMS week ending September 24, 2026), a point that moves the rate down about a quarter-point cuts the monthly payment by roughly $67 — so a $4,000 point breaks even at about month 60, year five. Keep the loan past year five and the point keeps paying; sell or refinance before it and the point cost more than it returned.

Two honest notes. First, the ~0.25%-per-point spread is illustrative — lenders price points differently by market, day, and loan profile, and the real spread comes from your Loan Estimate; the breakeven rule (cost ÷ monthly savings) is the constant. Second, points are prepaid interest, not a closing cost — the closing-costs calculator treats them as a separate input, and so should any quote comparison, or the numbers double-count. The points calculator carries the breakeven and the lender-credit mirror (taking a higher rate for cash at closing). And because the term matters as much as the spread, pair it with the payoff and refinance calculators before committing: points pay off on a schedule, not on a hunch.

Price points on your loan →

Frequently asked questions

Why is most of my early payment interest, not principal?

Because the interest bill is computed each month on the balance still outstanding — and early on, the balance is at its largest. On the cited default ($400,000 at 7.03%), the first year's payments are roughly 87% interest and 13% principal; that split flips slowly and only crosses over past the two-thirds point of the term. The amortization calculator renders the year-by-year schedule so you can see the crossover for your own loan.

Does the 15-year loan still win if I can't afford the higher payment?

The 15-year's advantage is entirely the interest saved by paying faster — it isn't automatically better, it's a bigger monthly commitment (the comparison runs the 15-yr at 6.42% against the 30-yr at 7.03%, both on $400,000). If the higher payment strains your budget, the 30-year plus voluntary extra principal keeps the flexibility to pay more in good months and less in tight ones — the schedule responds either way.

When does refinancing make sense relative to the amortization schedule?

Refinancing resets the schedule: a new loan restarts the interest-heavy early years on the remaining balance, so the math depends on your rate spread, your remaining term, and how long you'll stay. Run both schedules side by side in the amortization calculator before deciding — the calculator shows the interest-vs-principal shape you'd be trading into. See the refinance calculator for the decision math.

Is the biweekly "extra payment" real, or a myth?

It's real, and the mechanism is simple: 26 half-payments a year equals 13 full payments. Because a year has 12 months but 26 two-week periods, you make one extra full payment annually — equivalent to adding one-twelfth of your monthly payment each month. On the cited default ($400,000 at 7.03%, 30 years), that shortens the payoff by years. What is a myth: semi-monthly payments (24 per year) save nothing — 24 halves are exactly 12 full payments, so there's no extra principal and no acceleration.

Does a biweekly program charge for something I can do free?

Often, yes. The result comes entirely from paying 13 payments a year — which you can replicate yourself by adding one-twelfth of your monthly payment to each payment as extra principal, at no fee. A servicer-run biweekly program produces the same schedule; a third-party plan that holds your money between debits and charges a fee is selling you the same math. What matters is that the extra reaches principal immediately.

What about my escrow — does biweekly touch it?

No. Escrow for taxes and insurance is a separate accounting from principal and interest; a biweekly P&I arrangement doesn't change it, and your county's tax schedule doesn't move. Watch one real escrow pitfall: if your servicer recalculates escrow after a tax or insurance change, the monthly total can rise even while the biweekly principal plan saves you interest — two different numbers moving in two different directions. Compare P&I separately from the escrow line.

How do I calculate the break-even on discount points?

One formula: break-even months = total points cost ÷ monthly payment saving. The cited default: one point costs 1% of the loan ($4,000 on a $400,000 loan) and typically buys about a 0.25% rate reduction (band 0.125–0.25%). The CFPB's own worked example — $3,000 in points saving $50/month — breaks even at 60 months (five years). Keep the loan past the break-even and the point pays; sell or refinance before it and the point cost more than it returned.

Are points worth it if I might refinance soon?

Usually not — a refinance restarts the schedule and the points paid on the old loan don't carry over, so if the break-even sits past your likely refinance date, the points were a cost, not a saving. Points reward certainty about staying; if your stay is short or uncertain, a lender credit (a negative point — a higher rate for cash at closing) is the mirror trade worth pricing too. Both are on the points calculator.