Most people don't know their blended debt rate. Without it, you can't know whether your money is working for you or against you. Here's a framework for figuring that out.
Most people who invest have a rough sense of how their portfolio is performing. But ask those same people what their blended interest rate is across all their debt — mortgage, car loan, student loans, credit card — and you'll get a blank stare. That's a problem, because you can't know whether your money is working for you or against you without understanding both sides of the equation. This is a framework for thinking about that. Not a payoff strategy, not a debt elimination plan — just a clearer lens for understanding where you stand.
Most people think about their debt in silos — the mortgage is the mortgage, the car payment is the car payment. But your financial picture doesn't operate that way. A weighted average interest rate, or blended debt rate, takes all of your outstanding debt and calculates the single effective rate you're paying across everything. It weights each loan by its share of your total debt, so a $500,000 mortgage at 7% matters far more to your blended rate than a $10,000 credit card at 22%, simply because of scale.
The formula is straightforward:
Blended Rate = Σ (Loan Balance ÷ Total Debt) × Interest Rate
Say you're carrying the following:
| Debt | Balance | Rate | Weight | Contribution |
|---|---|---|---|---|
| Mortgage | $500K | 7.0% | 86.2% | 6.03% |
| Student Loans | $30K | 2.0% | 5.2% | 0.10% |
| Car Loan | $40K | 6.0% | 6.9% | 0.41% |
| Credit Card | $10K | 22.0% | 1.7% | 0.38% |
| Total | $580K | — | 100% | 6.92% |
Now the question is: what are you earning?
Using conservative assumptions — and that's all this exercise requires — say your portfolio looks like this:
Using a total portfolio of $290,000 (roughly half of the $580,000 in total debt above, to keep things grounded):
| Allocation | Amount | Return | Contribution |
|---|---|---|---|
| Market (60%) | $174,000 | 7.0% | 4.20% |
| HYSA (25%) | $72,500 | 3.0% | 0.75% |
| Cash (15%) | $43,500 | 0.0% | 0.00% |
| Total | $290,000 | — | 4.95% |
Blended Expected Return: ~4.95%
Now you have two numbers:
The gap is roughly -1.97% — meaning, on a purely mathematical basis, your debt is costing you more than your investments are expected to earn. It's worth being clear about what that number is and isn't: the return side is an estimate, not a guarantee. No one can accurately predict what markets will do, which is exactly why using conservative assumptions matters. The gap isn't a verdict — it's a directional signal. And right now, that signal is worth paying attention to.
That doesn't mean the answer is simple; tax implications, liquidity needs, and the long-term value of staying invested all matter. But it does mean you should know this. Because the conversation about your financial priorities looks very different when you're looking at a gap like this versus a scenario where your expected return comfortably exceeds your debt cost.
The point isn't to find a single right answer. The point is to stop guessing.
You can do this math in a spreadsheet — and if that's where you start, great. But a spreadsheet is static. It doesn't update when you make a payment, it doesn't connect to your investment accounts, and it doesn't show you how the gap shifts as your life changes.
That's where Potenza comes in. Rather than running two separate calculations that go stale the moment something changes, Potenza computes your blended debt rate and expected return from your actual balances — and lets you model what different decisions do to the gap. Pay off the car loan early. Shift your portfolio allocation. See how the spread moves. The math was never the hard part. Having everything connected, current, and interactive is what most people never get to.
Start there. Run the calculation. Know your gap. Everything else follows.
Most people are guessing about their money. You don't have to.
Potenza gives you the actual numbers behind your financial life — and shows you what moves the needle.
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