One-time amount & contribution
How much do you invest as a lump sum today, how much do you add each month? Both feed into the projection.
€
€0€200,000
€
€0€2,000
years
140
Buffett's advice for his own estate: 90% in a broad stock ETF, 10% in short-term government bonds. Calculate the projected value — and compare it with 100% stocks.
Warren Buffett recommended a radically simple split for his wife's inheritance: 90% in a low-cost S&P 500 index fund, 10% in short-term government bonds. Almost the full equity return, while the 10% buffer provides liquidity to buy in during crises — no stock picking, no market timing.
Source: Berkshire Hathaway shareholder letter 2013 (W. Buffett) · return assumptions per asset class
How the calculator works
How much do you invest as a lump sum today, how much do you add each month? Both feed into the projection.
90% stocks + 10% cash — the fixed ratio. Rebalance to 90/10 once a year, nothing more.
You see the projected portfolio value, the 90/10 split and an honest benchmark against 100% stocks.
→ Result: projected portfolio value + breakdown by asset class + return given up versus 100% stocks.
Allocation, projected growth versus a pure equity portfolio and the historical metrics — all live from your inputs above.
Buffett's 90/10 is projected with two assumptions: 90% stocks at 7.0% and 10% cash at 2.0% p.a. (nominal).
Blended, this gives an expected return of around 6.5% p.a. From this we project the one-time investment and monthly contribution over the period (monthly compounding, annuity formula).
Benchmark 100% stocks: the same contributions at 7% p.a. — so you can see how little return the 10% buffer costs.
Historically the maximum loss was only slightly below that of a pure equity portfolio (around −45% instead of −50%). Model calculation excluding taxes/costs/inflation, no guarantee.
Buffett's 90/10 captures almost the full equity return — the 10% buffer is dry powder for crises.
Buffett's idea: maximum simplicity, almost fully in stocks. ~6.5% p.a. in the model — just below 100% stocks, with a marginally smaller drawdown (around −45% instead of −50%).
The 10% cash is not a return driver but liquidity: in a crash you use it to buy in cheaply instead of having to sell stocks.
Four typical situations where opening it really pays off:
A strategy that works without stock picking or market timing.
In retirement, stability often matters more than the last bit of return.
How much return does the stability cost you versus 100% stocks?
Which amount goes into stocks, which into the cash buffer (90/10)?
Expected return = 90%·7% (stocks) + 10%·2% (cash) ≈ 6.5% p.a. This is used to compound the one-time investment + contribution monthly.
ETF savings plan, dividends, savings account vs. ETF, withdrawal plan — all the tools for building wealth.
All investment tools→Live · no sign-up