The Math Behind Giving Up a 3% Mortgage

If you bought your home during the pandemic, chances are you locked in an incredible mortgage rate—possibly around 3% or even lower.

For many homeowners today, that low rate feels like a golden handcuff. You may want a larger home, a different location, or a house that better fits your lifestyle—but the thought of giving up that rate stops you in your tracks.

So let’s break down the math.

Because the decision isn’t always as simple as it appears.

Why a 3% Mortgage Is So Powerful

Mortgage payments are based on the relationship between loan balance, interest rate, and time.

The formula lenders use to calculate mortgage payments comes from the standard amortized loan formula:

M = P \frac{r(1+r)^n}{(1+r)^n – 1}

Where:

M = monthly payment
P = loan principal
r = monthly interest rate
n = number of payments

Small changes in the interest rate dramatically change the monthly payment.

Example: $500,000 Mortgage

Let’s compare a $500,000 loan.

At 3% interest
Monthly payment ≈ $2,108

At 6.5% interest
Monthly payment ≈ $3,160

That’s a difference of roughly $1,050 per month.

Over 30 years, that difference becomes hundreds of thousands of dollars.

So yes—giving up a 3% mortgage is significant.

But this is where the conversation gets interesting.

The Hidden Factor: Home Equity

Many homeowners who bought during the pandemic also experienced substantial appreciation.

For example:

Purchase price in 2020: $500,000
Current value: $700,000

That creates $200,000 in equity.

That equity could potentially:

• Increase the down payment on a new home
• Reduce the size of the new loan
• Offset some of the higher interest rate

So the real comparison is not always 3% vs 6.5% on the same loan size.

It may be 3% on a smaller house vs 6.5% on a different financial structure.

Another Strategy: Keeping the 3% Mortgage

Some homeowners choose a different strategy entirely.

They keep their current home as a rental.

With such a low interest rate, the monthly payment may be low enough that rental income covers most or all of the mortgage.

In some cases this allows homeowners to:

• Keep their low-rate loan
• Move into a new home
• Build long-term wealth through rental property

This approach doesn’t work for everyone, but it’s worth exploring.

The Lifestyle Question

The math matters, but lifestyle matters too.

A home isn’t just a financial instrument.

It’s where your life happens.

If your home no longer fits your needs—whether it’s space, location, family, or work—the financial calculation is only part of the decision.

Sometimes the smartest move is optimizing your life, not just your interest rate.

The Bottom Line

Yes, a 3% mortgage is incredibly valuable.

But it shouldn’t automatically prevent you from exploring your options.

The right question isn’t simply:

“Should I give up my low interest rate?”

The better question is:

“What financial and lifestyle strategy makes the most sense for the next chapter of my life?”

If you’re curious what the numbers might look like for your situation, I’d be happy to help run the scenarios.

—
Jeni VanOrnum
Real Estate Advisor | Douglas County, Colorado