Ada County Mortgage Calculator
Rate History
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Our First Time Home Buyer Assistance Program is just what you need.Ada County mortgage calculator: plan the whole payment
Ada County includes Boise, Meridian, Eagle, Kuna, and Star, and it is Idaho's largest and most expensive major market. Growth has brought many newer subdivisions, so HOA dues and the homeowner's exemption both matter in the estimate. This page gives you current Ada County numbers, a worked example near the local median, and the Idaho tax and loan rules that belong in any honest estimate. Summit Lending LLC (NMLS 2394434) is a mortgage broker based in Garland, Utah. We compare loans from multiple wholesale lenders and can turn your calculator result into a real quote for a home in Ada County.
Ready to shop? Start a Ada County preapproval, or read about Ada County purchase loans.
Summit Lending LLC, NMLS 2394434, is based at 4542 W 14800 N, Garland, UT 84312 and serves borrowers in Utah, Texas, Idaho, Wyoming, Arkansas, and Arizona. Call 385-200-1470 or email [email protected].
Ada County numbers to start with
Redfin put the Ada County median sale price at about $556,000 for the three months ending September 2026, up 3.2% from the same period a year earlier. About 920 homes sold in September, compared with 847 a year earlier, and homes took a median of about 36 days to sell, versus 50 days last year, with an average sale-to-list ratio near 99.5% (Redfin Ada County data). Prices are a little higher than a year ago, and homes sell at close to list price, so expect competition for well-priced homes.
Homes in Kuna and Star often sit below the county median, while Eagle and parts of Boise can run well above it. Use a price that matches the neighborhood you are shopping.
Rates set the base of every estimate. Freddie Mac's weekly survey put the average 30-year fixed rate at 7.40% for the week of October 8, 2026, up from 7.28% a week earlier and 6.30% a year ago. It was the seventh weekly increase in a row and the highest reading since November 2023. The 15-year average was 6.73% (AP report on the Oct 8 survey; weekly history in the PMMS archive and on FRED). Those are national averages for borrowers with strong credit and roughly 20% down, not Ada County quotes. Freddie Mac publishes a new reading every Thursday (PMMS page), so if you are running numbers a few weeks from now, update the rate first.
What goes into an Ada County payment
- Principal and interest. The calculator's core result, set by price, down payment, rate, and term.
- Property tax. Based on value after the homeowner's exemption, multiplied by the levy for your taxing district.
- Homeowners insurance. Ask about wildfire risk on homes near the foothills, which can affect insurance cost.
- Mortgage insurance. PMI on conventional loans with less than 20% down, or FHA's annual premium.
- HOA dues. Very common in newer subdivisions in Meridian, Kuna, and Star.
Idaho's homeowner's exemption
Idaho exempts part of the value of an owner-occupied primary home from property tax. For 2026, the exemption is the lesser of $125,000 or 50% of the home's value, covering the home and up to one acre of land (Idaho State Tax Commission; Idaho Code 63-602G). On a $556,000 home, that means $125,000 of value is not taxed, so the taxable value is about $431,000. You apply with your county assessor after you buy, and it does not carry over from the seller automatically. The Ada County Assessor handles exemption applications and value notices for Ada County.
For the calculator, ask for the most recent tax bill on the address and check whether the seller had the exemption. If they did not, for example because the home was a rental, your bill could drop once yours is approved. If they did, the bill is a reasonable starting point.
Worked example: a $556,000 home in Ada County
Take a $556,000 home near the Ada County median with 10% down. The loan is $500,400. At 7.40%, principal and interest on a 30-year fixed is about $3,465 a month. At last year's 6.30%, the same loan would have been about $3,097, so the rate change alone adds about $367 a month.
A 15-year fixed at 6.73% raises the payment to about $4,423, while total interest drops to about $295,657, compared with about $746,881 over 30 years at 7.40%. Add tax, insurance, PMI, and HOA dues for the full number. If it is more than you want to carry, compare a lower price point, a larger down payment, a temporary or permanent rate buydown paid by the seller, or IHFA down payment assistance.
How the loan type changes your Ada County result
Most online calculators assume a conventional loan with a fixed rate, which can make the number look better or worse than what you would actually get. Here is how the same $556,000 Ada County home changes by program, using the 7.40% survey average as a stand-in rate. Your actual rate will differ by program and profile.
Conventional
Qualified buyers can put as little as 3% down on a one-unit primary home, which is $16,680 on $556,000 (Fannie Mae eligibility matrix). Below 20% down you pay private mortgage insurance, and you can ask to cancel it once the balance reaches 80% of the original value (CFPB on PMI). PMI is priced by credit score and down payment, so add it as a separate line in the calculator rather than guessing.
FHA
FHA requires 3.5% down with a 580 or higher score (HUD FHA overview). It also adds two insurance costs a basic calculator often skips: an upfront premium of 1.75% that is usually financed into the loan, and an annual premium paid monthly. For a base loan of $726,200 or less with more than 95% loan-to-value, the annual rate is 0.55% (HUD Mortgagee Letter 2023-05). On $556,000 with 3.5% down, the base loan is $536,540, the upfront premium adds $9,389, and principal and interest on $545,929 is about $3,780 at 7.40%. The monthly premium adds roughly $246, for about $4,026 before taxes and insurance. The 2026 FHA one-unit limit in Ada County is $586,500, so this price fits.
VA
Eligible veterans and service members can buy with no down payment and no monthly mortgage insurance (VA purchase loans). A one-time funding fee applies unless you are exempt, and for first use with less than 5% down it is 2.15% of the loan (VA funding fee). Financing that fee on $556,000 brings the loan to about $567,954, with principal and interest near $3,932 at 7.40%.
USDA
USDA guaranteed loans allow no down payment in eligible rural areas for households under the income limits (USDA guaranteed loans). Some areas on the edges of the county can be eligible, but most of the urban area is not. Check an address on the USDA eligibility map before you count on it.
2026 loan limits in Ada County
The 2026 conforming loan limit for a one-unit home in Ada County is $832,750 (FHFA announcement, FHFA county file). The FHA one-unit limit is $586,500 for the Boise metro area, which also covers Canyon County and Gem County (HUD announcement, HUD lookup).
Down payment help in Idaho
Idaho Housing and Finance Association offers down payment and closing cost assistance of up to 8% of the sales price, repaid as a second loan, with a minimum of $500 of your own funds (IHFA down payment help). IHFA says a credit score of 620 or higher is typically beneficial for its loans (IHFA homebuyers). If you use it, add the second loan's payment, if any, to your estimate. Idaho also lets first-time buyers deduct deposits to a first-time homebuyer savings account from state taxable income (Idaho State Tax Commission). Our Ada County first-time home buyer guide covers both in detail.
From a calculator estimate to a real number
- Run a few scenarios here. Try two prices, two down payments, and both a 30-year and 15-year term so you know your range.
- Get preapproved. A preapproval means a lender checked your credit, income, and assets. The CFPB points out that lenders use the terms prequalification and preapproval differently, so ask what was verified (CFPB comparison). Several mortgage credit checks within 45 days count as one inquiry for most scoring models, so shopping does not hurt your score more than once (CFPB on credit checks).
- Compare Loan Estimates. Lenders must send a Loan Estimate within three business days of your application, and the standard format makes side-by-side comparison easy (CFPB on Loan Estimates).
- Watch your debt-to-income ratio. Lenders compare your monthly debts, including the new payment, to gross monthly income (CFPB on DTI). A payment that fits your budget can still be too high for a program limit, or the reverse.
- Check the final numbers. Your Closing Disclosure arrives at least three business days before closing. Compare it to your Loan Estimate line by line (CFPB on Closing Disclosures).
Calculators for nearby areas
Cities in and near the county: Boise, Kuna, Star, Nampa, Caldwell, and Middleton. Elsewhere in Idaho: Canyon County, Gem County, Elmore County, Boise County, and Owyhee County. Or use the statewide Idaho mortgage calculator.
Related pages
See the Ada County mortgage overview, Ada County refinancing, Ada County construction loans, Ada County reverse mortgages, and Ada County commercial loans. Statewide, compare Idaho mortgage loans, Idaho purchase loans, Idaho refinancing, Idaho preapproval, Idaho mortgage calculator.
Sources
- Redfin, Ada County, ID housing market
- Redfin, Idaho housing market
- AP via WTOP, Freddie Mac rates for Oct 8, 2026
- Freddie Mac PMMS archive
- Freddie Mac Primary Mortgage Market Survey
- FRED, 30-Year Fixed Rate Mortgage Average
- Idaho State Tax Commission, homeowner's exemption
- Idaho Code 63-602G, homestead exemption
- Ada County Assessor
- Fannie Mae Eligibility Matrix
- CFPB, private mortgage insurance
- HUD, Let FHA loans help you
- HUD Mortgagee Letter 2023-05, FHA annual MIP (PDF)
- VA purchase loan
- VA funding fee and closing costs
- USDA Single Family Housing Guaranteed Loan Program
- USDA property eligibility map
- FHFA, 2026 conforming loan limits
- FHFA 2026 county loan limit list
- HUD No. 25-145, 2026 FHA loan limits
- HUD FHA mortgage limits lookup
- Idaho Housing and Finance Association, down payment help
- Idaho Housing and Finance Association, homebuyers
- Idaho State Tax Commission, first-time homebuyer savings account
- CFPB, prequalification vs. preapproval
- CFPB, when a lender checks your credit
- CFPB, What is a Loan Estimate?
- CFPB, debt-to-income ratio
- CFPB, What is a Closing Disclosure?
Information on this page is for general education and is current as of October 2026. It is not a commitment to lend or a rate quote. Program rules, limits, and availability change, and approval depends on your credit, income, assets, property, and lender guidelines. Summit Lending LLC, NMLS 2394434. Equal Housing Opportunity.
