100 Minus Age Asset Allocation Calculator

Classic '100 minus age' rule: stock allocation = 100 - age. 30 years old = 70% stocks, 30% bonds. 60 years old = 40% stocks, 60% bonds. Modern variants use 110 or 120 minus age for higher equity exposure.

Quick example

With your age of 35, the result is 65.00%. Change any figure and watch the output shift — it's often more useful to see the pattern than to memorise the formula.

What's happening under the hood

Stock % = 100 - age. Remainder in bonds. The formula is listed in full below. If the number looks off, you can retrace the calculation by hand — that's the point of showing the working.

Where this fits in planning

This is a "what-if" tool, not a forecast. Use it to test ideas before committing: what happens if the rate is 2% lower than hoped, what happens if you add five more years. The value is in the scenarios you run, not the single answer you get from the defaults.

What this doesn't capture

Steady-rate math ignores real-world volatility. Actual returns are lumpy; sequence-of-returns risk matters most in drawdown; fees and taxes drag on compound growth; and behaviour changes in drawdowns can reduce outcomes below the projection. The number represents one scenario rather than a forecast.

Where to go next

This calculation rarely sits alone in a planning exercise. If you're running these numbers, you'll probably also want the compound interest calculator, the fire calculator, and the asset allocation calculator — each one answers a different question in the same territory. Treating them as a set rather than in isolation usually produces a more honest picture.

Worked example

Suppose you are 45 years old. The formula gives 100 − 45 = 55. This means 55% stocks and 45% bonds. If your portfolio is worth 200,000 in your currency, the allocation becomes 110,000 in stocks and 90,000 in bonds. If you return to the calculator at age 50, the allocation shifts to 50% stocks and 50% bonds on the same portfolio size, which would mean rebalancing 10,000 from stocks into bonds annually to keep pace with the changing rule.

Common situations where this rule appears

• Early-stage retirement planning when a simple starting point is more useful than no starting point
• Discussions about how asset allocation typically evolves across decades
• Educational contexts explaining the relationship between age and risk exposure
• Baseline comparison when evaluating a personalised or professionally designed allocation

What the result shows and does not show

The calculator shows how a single variable—age—produces a theoretical split between two broad asset classes. It does not account for income stability, existing assets, time horizon for specific goals, market conditions, tax environment, or personal risk tolerance. The output is for educational illustration and models one algorithmic approach to a complex decision.