Planning tool

Home Affordability Calculator

Explore an illustrative home-price planning range using your income, debts, down payment and your own assumptions. This is education, not underwriting.

Last reviewed: September 30, 2026

Planning tool

Explore an illustrative price range

Fields marked * are required. All math runs in your browser. InterWest does not see, save or track your numbers.

Gross monthly income ($) *

Total household income before taxes and deductions.

Monthly debt payments ($) (optional)

Minimum payments such as car loans, student loans and credit cards. Don't include rent.

Estimated down payment ($) (optional)

Cash you expect to put toward the purchase.

Interest rate you want to assume (%) *

No InterWest rate is shown. Enter your own assumption.

Loan term *

The estimate assumes a fixed rate for the full term.

Estimated property taxes per year ($) (optional)

Estimated homeowners insurance per year ($) (optional)

HOA dues per month ($) (optional)

Planning assumptions

Lower planning ratio (%) *

Your share of gross income for all debts including housing. You can change this.

Upper planning ratio (%) *

The top of your planning range. This is not an InterWest limit.

The 36% and 43% starting values are general reference points from consumer education materials. They are not InterWest underwriting rules. Real limits vary by loan program, credit, reserves and other factors, and a comfortable budget may be lower.

How the planning range is calculated

For each planning ratio: housing budget = gross monthly income × ratio − monthly debt payments. Estimated taxes, insurance and HOA dues are subtracted to find a principal-and-interest amount. That amount is converted into a loan amount using the standard fixed-rate formula, and your down payment is added to show a home price.

About debt-to-income ratios

A debt-to-income ratio is your monthly debt payments divided by your gross monthly income. Lenders use it as one way to measure whether you can manage payments. The 36% and 43% starting values are general reference points from consumer education materials. They are not InterWest policy. You can change them, and actual limits differ by program and borrower.

What actually determines qualification

Qualification depends on underwriting, the loan program, credit history, income and asset documentation, the property, reserves and other factors. A comfortable budget may also be well below any lender maximum, so think about savings goals and other expenses too.

Privacy

The math runs in your browser. InterWest does not receive, store or track your income, debts, down payment or any other number you enter.

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Keep planning

Estimates are a starting point. These guides explain what comes next.

Mortgage preapproval

How a preapproval differs from a calculator estimate.

First-time home buyer guide

Budgeting, programs and questions for a first purchase.

Home loan options

Compare conventional, FHA, VA, USDA and Idaho Housing paths.

Book a consultation

Talk through your own numbers with the InterWest team.

Official references

Program information used on this page

Program information can change. These official resources support the specific contexts described below; confirm current rules before relying on them.

Consumer Financial Protection Bureau: What is a debt-to-income ratio?
Defines debt-to-income as monthly debt payments divided by gross monthly income, and explains how lenders use it.
Consumer Financial Protection Bureau: Prequalification and preapproval letters
Explains key mortgage terms and the difference between official loan documents and initial estimates.

A useful next step

Talk through your questions.

A preapproval conversation turns an illustration into a real review.

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