Compare net worth when extra money goes to your mortgage versus investments — either as recurring monthly extra cash or as a lump sum split once at the start.
This calculator compares two strategies under a strict cash-flow-neutral rule.
In monthly extra cash mode, both paths spend the same amount every month; only the allocation of that extra differs. In lump sum at start mode, a one-time amount is split at the beginning; thereafter only the regular mortgage payment repeats until payoff (then the full prior monthly budget is invested, matching the payoff rule in monthly mode).
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.
Pick one: recurring monthly extra or a single lump at the beginning — not both.
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.
Applied at the very beginning of the analysis (start of month 1), before the first scheduled mortgage payment. The slider splits this amount between extra mortgage principal and the portfolio.
Enter a value between 1 and 75 years.
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.
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,
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 (for the recurring mortgage payment and, in monthly mode, the same total monthly budget).
In lump-sum mode, the one-time amount is the only discretionary cash beyond the regular payment at the start; the slider splits that lump. Afterward, both paths keep the same scheduled payment until payoff.
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 calculator shows a break-even gross expected return (before fees), on the same basis as the expected return input. Investing uses net return (gross minus your fee percentage). Solving for where the two extreme allocation strategies tie therefore depends on your fee input: higher fees raise the gross return needed for the investing path to catch up.
No. This calculator does not predict future returns or prices. It shows arithmetic outcomes based on the assumptions you enter.
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