Mortgage Calculator
Big decision, clear numbers. Three questions, one tool: what's my payment, how much faster can I be debt-free, and how much house can I actually afford.
Anyone with the link can see the numbers included in it.
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Last reviewed: July 20, 2026 · Formulas verified by automated tests before every release.
Three calculators in one
Monthly payment is the classic: loan amount, rate and term give you the principal-and-interest payment plus the total cost over the life of the loan. Pay off early shows what happens when you add extra money each month — usually the most motivating numbers on this page. Affordability works backwards: start from the payment that feels comfortable and see what loan amount it supports. Add your gross income in any mode to get the debt-to-income check.
M = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1) · DTI = housing payment ÷ gross monthly income
All mortgage tools in one place: the mortgage toolkit.
What is included in a mortgage payment?
Full monthly payment ≈ principal + interest + property taxes + homeowners insurance + mortgage insurance + HOA
The headline number lenders quote — and the main result above — is principal and interest (P&I). The bill you'll actually pay usually adds escrowed property taxes, homeowners insurance, PMI (if your down payment was under 20%) and any HOA dues. Use the "Estimate full monthly housing payment" block under the result: enter your own figures and see the honest total. We keep those fields empty by default — taxes and insurance vary too much by location for averages to mean anything.
Putting down less than 20%? Estimate PMI separately — monthly cost, LTV and the scheduled month you can request cancellation — then paste the number into the PMI field here.
DTI zones at a glance
| DTI (housing / income) | Zone | What it means |
|---|---|---|
| Up to 28% | 🟢 Comfortable | The traditional lending guideline |
| 28% – 36% | 🟡 Acceptable | Approved often, budget feels it |
| Above 36% | 🔴 Stretched | Banks may still approve — living it is hard |
What banks won't tell you
- The advertised payment is not the real payment. Property tax, homeowners insurance, PMI and HOA fees typically add 20–40% on top of principal and interest.
- A longer term is sold as "affordable" — it maximizes interest. The lower monthly payment of a 30-year loan can double the total interest versus 15 years.
- Approval is not affordability. Lenders may approve payments up to 43–50% of income. The traditional comfort guideline is 28% — that gap is where financial stress lives, and it's why our indicator turns red above 36%.
- Early extra payments are disproportionately powerful. In the first years almost the whole payment is interest; every extra dollar then goes straight at the principal.
Watch out for
- Adjustable rates that jump after an introductory period — always ask for the fully-indexed rate.
- Prepayment penalties: some loans charge you for paying off early. Check before signing.
- PMI that quietly stays on after you reach 20% equity — you often must request its removal.
- Comparing offers by rate alone: fees and points can make a "lower rate" cost more. Compare APR and total cost.
Go deeper: our mortgage guides
- Documents you need for a mortgage — the full checklist
- 12 questions to ask your lender before signing
- PMI explained: what it costs and how to remove it early
Disclaimer
This tool provides estimates for information purposes only and is not financial advice. Real offers include taxes, insurance, fees and conditions that vary by lender and location — review the full loan estimate and consider independent advice before committing.
Choose the right calculator
- How much do I need up front — and when will I have it? → Down Payment Calculator
- What does putting down less than 20% cost me? → PMI Calculator
- Comparing two loan offers? → Loan Calculator (A/B compare)
Sources, assumptions and limitations
- Formula: M = P × r(1+r)ⁿ / ((1+r)ⁿ − 1); full payment ≈ P&I + taxes + insurance + PMI + HOA (PITI)
- Assumptions: Fixed-rate amortizing loan; extras are user-entered (no regional averages); DTI zones follow the common 28/36 lending guideline.
- Not included: Closing costs, points, ARM adjustments, tax deductibility, escrow cushion rules.
- Sources: CFPB: P&I vs total monthly payment
- Last reviewed: July 22, 2026 by the CalcNotebook team
Frequently asked questions
How is the monthly mortgage payment calculated?
With the standard amortization formula: M = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1), where P is the loan amount, r the monthly rate (annual ÷ 12) and n the number of monthly payments. This covers principal and interest; taxes and insurance come on top.
What is DTI and why does the calculator show a color indicator?
Debt-to-income ratio compares your housing payment to your gross monthly income. Lenders traditionally treat up to 28% as comfortable and 28–36% as acceptable. Green, yellow and red zones show where your numbers land — because a bank may approve more than is comfortable to live with.
Do extra payments really make a big difference?
Yes, especially early in the loan when most of each payment is interest. For example, $300 extra per month on a $320,000 loan at 6.5% pays it off about 9 years sooner and saves roughly $138,000 in interest.
Does this include property tax, insurance and HOA?
No — this calculates principal and interest only. Property tax, homeowners insurance, PMI (if your down payment is under 20%) and HOA fees typically add 20–40% on top of the base payment. Budget for the full number, not just P&I.
Is 15 or 30 years better?
A 15-year term roughly halves total interest but raises the monthly payment significantly. A practical middle path: take the 30-year for flexibility and pay it like a 15-year with extra payments — you keep the option to drop back to the lower payment if life happens.