Age-Based Allocation Rules Disagree by 20 Points — How to Choose

Ask four common age-based rules how much of your portfolio should sit in stocks and you can get four different answers — and the three "minus-age" variants alone are guaranteed to span exactly 20 percentage points at any age, before Vanguard's glide path even enters the picture. That's not noise or rounding; it's built into the math, as the guide on what these four rules actually assume breaks down in detail. The question this guide answers isn't which rule is "right" — none of them is — but which end of that spread actually fits your situation.

The 20-Point Spread Is Built Into the Formula

The three minus-age rules share one formula, stockPct = clamp(X − age, 0, 100), differing only in the constant X: 100, 110, or 120. Because 120 minus 100 is always 20, the gap between the most conservative (100-minus-age) and most aggressive (120-minus-age) variant is exactly 20 points at every age, before clamping near the edges. A 60-year-old gets 40% stocks under the 100-rule and 60% under the 120-rule — a 20-point gap with nothing in between to break the tie.

Layer in Vanguard's published glide path and the spread can widen further, or land inside the same band, depending on how far you are from your target retirement age:

• Age 35, retiring at 65: 65% (100-rule), 75% (110-rule), 85% (120-rule), 90% (Vanguard) — a 25-point spread. Vanguard sits above all three because age 35 is still inside its 90%-equity hold zone.
• Age 50, retiring at 65: 50%, 60%, 70%, 74% (Vanguard) — a 24-point spread. Vanguard is 15 years from retirement, partway down its linear glide from 90% to 50%.
• Age 60, retiring at 65: 40%, 50%, 60%, 58% (Vanguard) — back to a 20-point spread, with Vanguard now inside the minus-age band instead of above it.

The asset allocation by age calculator runs all four against your own age and retirement date so you're looking at your actual numbers, not a generic example.

What Actually Justifies the Aggressive End

A wider stock allocation isn't automatically right for anyone with a long time horizon — it's a bet that you can tolerate volatility without needing to sell during a downturn. Factors that make the aggressive end (110-minus-age, 120-minus-age, or Vanguard's early hold zone) more defensible:

• A genuinely long horizon before you'd need the money — not just years until a stated retirement age, but years until you'd actually have to draw the portfolio down.
• Stable, reliable income from employment or other guaranteed sources, so a market drop doesn't force you to sell equities to cover expenses.
• Other guaranteed income in retirement — a pension or Social Security that covers baseline spending — which reduces how much the portfolio itself has to carry.
• Demonstrated tolerance for volatility, meaning you've actually sat through a decline without changing your plan, not just an assumption that you would.

What Actually Justifies the Conservative End

The 100-minus-age end of the spread, or Vanguard's post-retirement glide toward 30%, is the more defensible choice when:

• The money will be needed on a fixed, near-term schedule — a house down payment, tuition, or retirement income you're about to start drawing.
• Income is unstable, so a downturn could force a portfolio sale at the worst possible time to cover a gap.
• There's no other safety net — no pension, limited Social Security, no separate emergency fund — so the portfolio has to absorb shocks the rest of your finances can't.
• You're within the sequence-of-returns risk window — the years immediately before and after retirement, when a bad market and ongoing withdrawals compound each other. The guide on sequence-of-returns risk covers why that window is disproportionately dangerous, which is exactly why Vanguard's glide path de-risks fastest in the seven years after retirement rather than holding a flat allocation.

A Starting Point, Not a Verdict

None of these four numbers was computed from your actual finances — they're all functions of age (and, for Vanguard, retirement date) alone. A reasonable way to use the spread: treat Vanguard's glide path as the default starting point, since it's the one real target-date funds actually run and the only one of the four built in phases rather than a straight line. Then adjust up toward 120-minus-age if the aggressive-end factors above clearly apply to you, or down toward 100-minus-age if the conservative-end factors do. Landing exactly on one of the four numbers isn't the goal — understanding which direction your circumstances push you, relative to the spread, is.

Retirement Age Moves the Whole Band

Only Vanguard's path uses your target retirement date — the three minus-age rules are pure functions of current age and ignore it entirely. That makes retirement age the biggest lever for anyone planning to retire earlier than 65: someone targeting 55 sees Vanguard's 90% hold zone end at 30 instead of 40, and the 30% floor begin at 62 instead of 72, which pulls Vanguard's line well above where it would sit for a standard 65-year-old retirement. That's the scenario the Coast FIRE and Barista FIRE audience is usually in, and it's why the asset allocation calculator exposes retirement age as its own input.

This guide is informational only and is not financial, investment, or tax advice. The minus-age figures are common rules of thumb, not standards; the Vanguard path is a model of its published glide-path anchor points, not the exact holdings of any specific fund. Consult a qualified financial professional before making investment decisions.

Frequently asked questions

Is a 20-point spread normal, or does it mean one of these rules is wrong?

It's normal — it's arithmetic, not disagreement. Because the three minus-age rules use constants 100, 110, and 120, the gap between the most and least conservative is always exactly 20 points at any given age (before clamping near 0% or 100%). None of the four rules is "wrong"; they're answering the same question with different built-in assumptions about how much risk is appropriate.

Which factors matter most when deciding which end of the range to lean toward?

Time horizon before you'd actually need the money, income stability, whether you have other guaranteed income like a pension or Social Security, and your demonstrated (not assumed) tolerance for watching the portfolio decline. Someone with a stable income and 20+ years to retirement can defend leaning toward the aggressive end; someone drawing down the portfolio within the next few years, especially without other income, has a stronger case for the conservative end.

Why would I ever pick a number lower than 100-minus-age?

The four rules here only cover a common range — nothing prevents a more conservative allocation if your circumstances call for it, such as a near-term cash need that shouldn't be exposed to market risk at all. The rules are reference points, not a floor.

Does the spread ever narrow to zero?

Only when the minus-age formula clamps at the edges — for example, a 105-year-old scores 0% under the 100-rule but only 15% under the 120-rule, still a 15-point gap, not zero, because clamping affects each constant differently near the boundary. In practice the three minus-age rules never fully converge; the gap can only shrink, not disappear.

This guide is for informational and educational purposes only. It is not financial, tax, or legal advice. Tax rules are complex, fact-specific, and subject to change. Consult a qualified tax or financial professional before making IRA contribution or conversion decisions.

Last reviewed: September 2026 · Against primary sources cited in the body.