Same starting capital. Same monthly contribution. Same lifestyle. Two completely different strategies for what to actually do with the money. This calculator runs them side-by-side so you can see — with your own numbers — which one leaves your estate larger.
Save into a diversified index fund (S&P 500 historical CAGR ~9%). At retirement, sell shares each year to fund living expenses, paying long-term capital gains tax on every sale. Portfolio drains over time. Whatever's left at death passes to heirs at a stepped-up basis.
Save into Bitcoin (15-year CAGR ~60%; 15% used here as a conservative forward assumption). At retirement, borrow against your BTC each year to fund living expenses. No selling, no capital gains tax, ever. BTC keeps appreciating. Estate passes to heirs tax-free at stepped-up basis with debt paid off from collateral. Full breakdown →
Both strategies use the same shared inputs (your age, savings, lifestyle). The strategy-specific cards below let you tune the assumptions for each. Results update live.
Nominal future dollars look enormous because compounding makes any number look huge over 50+ years. The "net estate" figure on each card is converted back to today's purchasing power using your inflation rate. It's the real answer to: "How much would my heirs receive, in dollars I currently understand?"
The traditional strategy's lifetime tax bill is also shown in real dollars. That's wealth that left your family permanently and went to the federal government. Under BBD, that number is zero because borrowing isn't income — and at death, the stepped-up basis erases the gains entirely.
If your retirement number doesn't work, only three levers actually matter. Most people only touch one.
The most powerful variable, and the one you can't get back. Five extra years of compounding can roughly double your final number. Start now, even if the amount is small.
Doubling your monthly contribution doesn't double your nest egg — it does much more, because each new dollar gets the same compounding runway. This is the only lever fully under your control.
A 9% portfolio doubles every ~8 years. A 20% portfolio doubles every ~3.8. What you own — and whether it can be borrowed against efficiently — is the single biggest decision you'll make.
Bitcoin's 60% historical CAGR is a curve from a tiny base. Forward returns will be lower as the asset matures. The default 20% assumption is intentionally conservative, but pick whatever number you actually believe.
BBD requires discipline and a healthy collateral cushion. Margin calls have wiped out leveraged BTC holders multiple times. Stay well below your liquidation LTV — even when "safe" math suggests you could borrow more.
The traditional path is more legible to most people. Index funds in a 401k require zero ongoing thought. BBD requires active loan management and competent custody. Higher reward, more responsibility.
Tax law can change. Stepped-up basis at death has been targeted for elimination multiple times. The strategy still works without it (deferral alone is huge) but the tax-wipeout benefit isn't guaranteed across decades.