Compare the net worth effects of using the same monthly cash to pay down your mortgage faster vs. investing
This calculator compares two strategies under a strict cash-flow-neutral rule.
Both paths spend the same amount of money every month; only the allocation differs.
The results show arithmetic under your assumptions.
Current estimated value of your home.
Home price growth is typically 2-3% per year but can vary wildly between cities, neighbourhoods, and over time.
Your total monthly budget. This equals your mortgage payment plus extra cash available.
This amount is allocated between mortgage paydown and investing based on the slider setting.
Enter a value between 1 and 75 years.
The slider controls how your extra cash is allocated. Your regular mortgage payment always goes to the mortgage until it's paid off.
With these inputs, mortgage will be paid off in — years and — months, and net worth will be $— at the end of your — year time horizon.
For a more detailed and customizable mortgage analysis, see our Mortgage Calculator — Payments, Interest, and Amortization.
For a more detailed and customizable investment analysis, see our Investment Calculator – Inflation Adjusted.
If 100% of extra cash allocated to paying off mortgage faster, net worth is $— after — years.
If 100% of extra cash allocated to investing, net worth is $— after — years.
If —% of extra monthly cash is allocated to mortgage payments, your mortgage will be paid off in — years and — months, compared to — years and — months with all extra cash invested (—).
Total interest paid on mortgage under current assumptions: $—
Total interest earned on investments under current assumptions: $—
This calculator enforces identical monthly cash outflows in both strategies.
This tool does not predict housing prices or markets.
It shows arithmetic under your assumptions.
This depends on interest rates, expected investment returns, time horizon, and how much cash you have available each month. This calculator compares both strategies using identical monthly cash outflows and shows the resulting net worth under your assumptions.
There is no universally correct answer. Paying down a mortgage produces a guaranteed return equal to the mortgage rate, while investing introduces market risk. This tool shows how those trade-offs affect net worth when the same monthly cash is used in either strategy.
Cash-flow neutral means both strategies spend the same amount of money every month. The difference is how that cash is allocated — toward mortgage payments or investments — not how much is spent.
Once the mortgage is fully paid off, the calculator assumes the entire monthly budget continues to be invested. This keeps cash outflows identical in both strategies and prevents distorted comparisons.
Home price growth can be included as an optional assumption. By default, results focus on mortgage balances, investments, and net worth under explicit inputs rather than housing price predictions.
This version uses a simplified investment account with no tax drag. The goal is to isolate the arithmetic of mortgage paydown versus investing before introducing jurisdiction-specific tax complexity.
Paying down a mortgage produces a return equal to the mortgage interest rate, after considering compounding. Unlike investments, this return is not subject to market volatility.
The break-even return is the annual investment return required for investing to produce the same net worth as accelerated mortgage payoff, given the same monthly cash outflow.
No. This calculator does not predict future returns or prices. It shows arithmetic outcomes based on the assumptions you enter.
Disclaimer: All content on The Long Math — including articles, essays, calculators, tools, or any other material — is provided solely for educational and informational purposes and does not constitute financial, tax, legal, or investment advice. Any results or projections are based on simplified models, assumptions, and user-supplied inputs and may not reflect real-world outcomes. You are responsible for evaluating the accuracy and applicability of the information provided and for conducting your own due diligence. Before making financial decisions, consult a qualified professional.