What You Need To Know About Online Mortgage Calculators

Lee Welbanks • January 8, 2025

You’d think an online calculator is a pretty straightforward device, one that you should be able to place your confidence in, and for the most part, they are. Calculators calculate numbers. The numbers are reliable, but how you interpret those numbers, not so much, especially if the goal is mortgage qualification.


If you rely on the numbers from a “What can I afford” or “Mortgage Qualification” calculator without talking to an independent mortgage professional, you’re going to be misinformed.


Don’t be fooled. Even though an online mortgage calculator can help you calculate mortgage payments or help you assess how additional payments would impact your amortization, they’ll never be able to give you an exact picture of what you can afford and how a lender will consider your mortgage application.


While mortgage calculators are objective, mortgage lending isn’t. It’s 100% subjective. Lenders consider your financial situation, employment, credit history, assets, liabilities, the property you are looking to purchase. Then, they will compare that with whatever internal risk profile they are currently using to assess mortgage lending. Simply put, they don’t just look at the numbers.


An online calculator is a great tool to help you run different financial scenarios and help assess your comfort level with different payment schedules and mortgage amounts. However, if you rely on an online calculator for mortgage qualification purposes, you’ll be disappointed.


The first step in the mortgage qualification process is a preapproval. A preapproval will examine all the variables on your application, assess your financial situation, and provide you with a framework to buy a property based on your unique circumstance.


Securing a preapproval comes at no cost to you and without any obligation to buy. It’ll simply allow you the freedom to move ahead with confidence, knowing exactly where you stand. Something a calculator is unable to do.


Please connect anytime if you’d like to talk more about your financial situation and get a preapproval started. It would be a pleasure to work with you.


Lee Welbanks
By Lee Welbanks August 26, 2026
If the title of this article caught your attention, chances are your family is growing. Congratulations. If you’re thinking now is the right time to move into a home that better fits your growing family—but you’re unsure how parental leave affects your ability to qualify for a mortgage—you’re in the right place. Here’s the good news. Qualifying for a mortgage while on parental leave is possible when it’s done correctly. When you work with an independent mortgage professional, lenders can often qualify you based on your return-to-work income , as long as you can provide documentation confirming you have guaranteed employment waiting for you. A word of caution If you walk into a bank branch and disclose that you’re currently on parental leave, there’s a chance the bank will only allow you to qualify using your parental leave income. That can significantly reduce your borrowing power. Parental leave income is typically limited to 55% of your previous earnings, up to a weekly maximum. Qualifying on that amount alone can restrict your options and impact the type of home you can purchase. Why lender choice matters One of the biggest advantages of working with an independent mortgage professional is choice . You’re not limited to one lender’s rules or products. Some lenders will allow you to qualify using 100% of your confirmed return-to-work income , which can make a meaningful difference in your approval amount and overall options. What you’ll need to qualify Most lenders will require an employment letter that includes: Employer name (preferably on company letterhead) Your job title Original start date (to confirm probation has been completed) Confirmed return-to-work date Guaranteed salary upon return Lenders want reassurance that your income will resume once parental leave ends. You may also be asked to provide income history from the past couple of years, which is standard for most mortgage applications. One important note Whether or not you actually return to work after parental leave is entirely your decision. From a mortgage perspective, qualification is based on having a confirmed position available to you at the time of approval. If you have questions about qualifying for a mortgage while on parental leave—or anything mortgage-related—please connect anytime. I’d be happy to walk you through your options and help you plan with confidence.
By Lee Welbanks August 19, 2026
Can You Afford That Mortgage? Let’s Talk About Debt Service Ratios One of the biggest factors lenders look at when deciding whether you qualify for a mortgage is something called your debt service ratios. It’s a financial check-up to make sure you can handle the payments—not just for your new home, but for everything else you owe as well. If you’d rather skip the math and have someone walk through this with you, that’s what I’m here for. But if you like to understand how things work behind the scenes, keep reading. We’re going to break down what these ratios are, how to calculate them, and why they matter when it comes to getting approved. What Are Debt Service Ratios? Debt service ratios measure your ability to manage your financial obligations based on your income. There are two key ratios lenders care about: Gross Debt Service (GDS) This looks at the percentage of your income that would go toward housing expenses only. Total Debt Service (TDS) This includes your housing costs plus all other debt payments—car loans, credit cards, student loans, support payments, etc. How to Calculate GDS and TDS Let’s break down the formulas. GDS Formula: (P + I + T + H + Condo Fees*) ÷ Gross Monthly Income Where: P = Principal I = Interest T = Property Taxes H = Heat Condo fees are usually calculated at 50% of the total amount TDS Formula: (GDS + Monthly Debt Payments) ÷ Gross Monthly Income These ratios tell lenders if your budget is already stretched too thin—or if you’ve got room to safely take on a mortgage. How High Is Too High? Most lenders follow maximum thresholds, especially for insured (high-ratio) mortgages. As of now, those limits are typically: GDS: Max 39% TDS: Max 44% Go above those numbers and your application could be declined, regardless of how confident you feel about your ability to manage the payments. Real-World Example Let’s say you’re earning $90,000 a year, or $7,500 a month. You find a home you love, and the monthly housing costs (mortgage payment, property tax, heat) total $1,700/month. GDS = $1,700 ÷ $7,500 = 22.7% You’re well under the 39% cap—so far, so good. Now factor in your other monthly obligations: Car loan: $300 Child support: $500 Credit card/line of credit payments: $700 Total other debt = $1,500/month Now add that to the $1,700 in housing costs: TDS = $3,200 ÷ $7,500 = 42.7% Uh oh. Even though your GDS looks great, your TDS is just over the 42% limit. That could put your mortgage approval at risk—even if you’re paying similar or higher rent now. What Can You Do? In cases like this, small adjustments can make a big difference: Consolidate or restructure your debts to lower monthly payments Reallocate part of your down payment to reduce high-interest debt Add a co-applicant to increase qualifying income Wait and build savings or credit strength before applying This is where working with an experienced mortgage professional pays off. We can look at your entire financial picture and help you make strategic moves to qualify confidently. Don’t Leave It to Chance Everyone’s situation is different, and debt service ratios aren’t something you want to guess at. The earlier you start the conversation, the more time you’ll have to improve your numbers and boost your chances of approval. If you're wondering how much home you can afford—or want help analyzing your own GDS and TDS—let’s connect. I’d be happy to walk through your numbers and help you build a solid mortgage strategy.