Bond vs Stock Allocation Calculator
The right balance between stocks and bonds depends on your time horizon, risk tolerance, and income needs. Stocks historically offer higher long-term returns but with significant short-term volatility. Bonds provide stability and income but with lower long-term growth. This calculator projects the 10-year and 30-year expected value of your portfolio at different stock/bond allocations, and shows the estimated portfolio standard deviation (risk) for each mix, so you can compare the trade-off between growth and stability.
Portfolio return and risk formulas
Expected Return = w(s) * r(s) + w(b) * r(b)
Portfolio Variance = w(s)^2 * std(s)^2 + w(b)^2 * std(b)^2 + 2*w(s)*w(b)*std(s)*std(b)*rho
Portfolio Std Dev = sqrt(Portfolio Variance)
Future Value (n years) = Balance * (1 + Expected Return)^n
where w = weight, r = return, std = standard deviation, rho = correlation
Source: Markowitz, H. (1952). Portfolio Selection. Journal of Finance, 7(1), 77-91.
Historical stock/bond allocation reference data
| Allocation (stocks/bonds) | Approx. nominal return | Approx. std deviation | Worst 1-year loss (historical) |
|---|---|---|---|
| 100% stocks / 0% bonds | ~10.2% | ~20% | ~-43% (2008) |
| 80% stocks / 20% bonds | ~9.1% | ~16% | ~-34% |
| 60% stocks / 40% bonds | ~8.1% | ~12% | ~-26% |
| 40% stocks / 60% bonds | ~7.0% | ~9% | ~-18% |
| 20% stocks / 80% bonds | ~5.8% | ~7% | ~-10% |
| 0% stocks / 100% bonds | ~4.9% | ~7% | ~-5% |
Historical figures approximate, sourced from Morningstar and Ibbotson historical data (1926-2023). Past performance does not guarantee future results.
Bond vs stock allocation: frequently asked questions
What is the classic rule for stock vs bond allocation?
A widely cited rule of thumb is to hold your age in bonds and the rest in stocks. For example, a 40-year-old would hold 40% bonds and 60% stocks. Modern variants use 110 or 120 minus age for the stock percentage to reflect longer lifespans. These are starting points, not prescriptions.
Why do bonds reduce portfolio volatility?
Stocks and bonds have historically had low or negative correlation in many market environments. When stocks fall sharply, investors often flee to the safety of government bonds, pushing bond prices up. This inverse behavior means holding both assets reduces the overall portfolio's swings, even if bonds have lower long-term returns.
What are the long-term historical returns of stocks vs bonds?
According to data compiled by Morningstar and Ibbotson Associates, the annualized return of US large-cap stocks from 1926 to 2023 was approximately 10.2%, while US intermediate-term government bonds returned approximately 4.9%. In real (inflation-adjusted) terms, stocks returned about 7.1% and bonds about 2.0% annually.
Should I hold more bonds as I approach retirement?
Many target-date funds automatically shift toward more bonds as the target retirement date approaches. This approach aims to reduce the risk of a large loss just before retirement, when there is less time to recover. However, if your retirement is long (25-30 years), holding too many bonds early in retirement may result in insufficient growth to sustain withdrawals.
What types of bonds should I hold?
Common bond categories include US Treasury bonds (lowest risk), investment-grade corporate bonds (slightly more yield and risk), and international bonds. Bond duration (short, intermediate, long) affects sensitivity to interest rate changes. Short-term bonds are less volatile; long-term bonds offer higher yield but more price risk. For most investors, intermediate-term bond index funds are a reasonable default.
Official sources
- SEC Investor.gov: Bonds and Fixed Income Products.
- FINRA: Asset Allocation.
- Federal Reserve: Selected Interest Rates (H.15).
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.