Portfolio Allocation Calculator (Stocks, Bonds, Cash)
Split a total investment amount into dollar amounts for stocks, bonds and cash from your target percentage weights, and check that the weights add up to 100%. Use it when building or rebalancing a diversified portfolio.
Last updated: September 2026
Formula below · 3 sources (investor.gov, sec.gov, Wikipedia) · Updated Sep 2026
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About this calculator
Portfolio allocation distributes a total investment across asset classes according to chosen percentage weights. Each allocation in dollars is totalAmount × (classPercent / 100), so the calculator shows Stocks = total × stock% / 100, Bonds = total × bond% / 100 and Cash = total × cash% / 100, rounded to whole dollars. It also adds up the three weights: if they sum to 100% every dollar is assigned; if not, it shows how much is left unassigned or over-assigned. The calculator does not choose the weights for you. A classic starting point is the '100 minus age' rule for the stock share, with '110 minus age' or '120 minus age' as more growth-oriented variants for longer lives; the right split also depends on your time horizon, risk tolerance and other income. Asset allocation is widely considered the dominant driver of long-term portfolio risk and return.
How to use
You have $50,000 to invest and choose a 60/30/10 allocation: 60% stocks, 30% bonds, 10% cash. Step 1 — Stocks: $50,000 × 60 / 100 = $30,000. Step 2 — Bonds: $50,000 × 30 / 100 = $15,000. Step 3 — Cash: $50,000 × 10 / 100 = $5,000. Step 4 — Verify: $30,000 + $15,000 + $5,000 = $50,000 ✓. The calculator shows 'Stocks $30,000 · Bonds $15,000 · Cash $5,000 (100% allocated)'. You would invest $30,000 in equities, $15,000 in bond funds, and keep $5,000 in a money market or savings account. Adjust the percentages to match your risk tolerance and time horizon.
Frequently asked questions
What is the best portfolio allocation for a long-term investor?
There is no single 'best' allocation — it depends on time horizon, risk tolerance, and financial goals. Historically, a higher stock allocation has delivered superior long-term returns but with greater volatility. A 90/10 stock-bond split suits aggressive investors with 20+ year horizons, while a 60/40 portfolio is a classic moderate benchmark. Target-date funds automatically shift toward bonds and cash as retirement approaches, which is a practical implementation of age-based allocation.
Why is diversification across asset classes important in portfolio allocation?
Different asset classes tend to respond differently to economic conditions. Stocks generally perform well during economic expansion but fall sharply in recessions. Bonds often rise when stocks fall, acting as a buffer. Cash provides stability and liquidity but earns little real return after inflation. Holding a mix smooths the portfolio's overall volatility without necessarily sacrificing long-term returns — a principle formalized by Harry Markowitz's Modern Portfolio Theory, for which he received the Nobel Prize in Economics in 1990.
How often should I rebalance my portfolio allocation?
Most financial advisors recommend rebalancing once or twice per year, or whenever any asset class drifts more than 5 percentage points from its target weight. For example, if a bull market pushes your stock allocation from 60% to 70%, rebalancing restores the intended risk profile by selling some equities and buying bonds or cash. Research suggests that rebalancing more than quarterly adds transaction costs without meaningfully improving returns, while never rebalancing allows risk to creep well beyond your intended level.
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