Compare mortgage strategies when your assets are in stocks. Add scenarios, edit the interest rate curve and stock sales directly on the chart.
⚠️ Disclaimer: This tool was hastily written for personal exploration. The numbers it produces may contain errors. Do not make financial decisions based on this tool without independently verifying the calculations.
Summary — All Scenarios
Scenario
Down Payment
Rate (start)
Initial Monthly Payment
Horizon
Interest Paid
Lost Profit*
Net Cost*
*Sale amounts are post-tax proceeds (what reduces the mortgage). Lost Profit = what those shares would have grown to by the horizon (after CGT on gain) minus what you received net — i.e. the profit you gave up by selling.
Net Cost = Interest Paid + Lost Profit. Lower is better.
Considerations (not modelled)▼ show
Capital gains tax — modelled as a flat rate on all stock sales. Real CGT depends on your cost basis and annual allowance.
House value appreciation — offsets the effective cost of interest; same across scenarios so not modelled.
Inflation — erodes the real cost of future interest payments; all values shown are nominal.
Mortgage fees & costs — arrangement fees, valuation, conveyancing — vary by lender and product.
Dividend income — selling stocks eliminates future dividends from those shares.
Variable-rate risk — the rate curve you draw is an assumption; actual rates are unpredictable.
Lump-sum overpayments — modelled as reducing principal immediately; monthly payment is recalculated for the remaining balance and term (mortgage recasting). Freed-up cash from lower payments is not modelled as reinvested.
Property tax — not included; adds a fixed ongoing cost that is the same regardless of financing strategy.
☰Scenario$0 interest
Rate: double-click chart to add breakpoint; drag orange dot to adjust rate/timing; click dot then Del or × to delete. |
Sales: click Add Stock Sale then click chart; drag purple dot left/right (time) or up/down (amount); click dot to edit amount.