How to Calculate Your Retirement Number: The Complete 2026 Guide

Blog › Finance · 10 min read · Published 2026-05-09

The 4% rule, estimating retirement expenses, inflation, Social Security integration, and catch-up strategies after 50.

What Is "Your Number"?

Your retirement number is the size of the portfolio that, if invested sensibly, will fund your lifestyle for the rest of your life. The most widely used heuristic is the 4% rule, derived from the 1998 Trinity Study, which back-tested portfolio survival over 30-year periods.

The 4% Rule Explained

If you withdraw 4% of your portfolio in year one and adjust withdrawals upward for inflation each subsequent year, a balanced portfolio (50–75% stocks, the rest bonds) had a very high probability of lasting at least 30 years across historic US data.

Inverted, this gives the famous multiplier: Number = annual spending × 25. If you need $60,000/year in retirement spending, your number is roughly $1,500,000.

Run different scenarios in the Retirement Calculator.

Step 1 — Estimate Your Retirement Expenses

Most retirees spend 70–85% of their pre-retirement income, but this varies widely. Build a realistic budget:

Housing: mortgage (often paid off), property tax, insurance, maintenance
Healthcare: Medicare premiums, supplemental insurance, out-of-pocket
Food, utilities, transport
Lifestyle: travel, hobbies, gifts, entertainment
Long-term care reserve for late-life needs

Step 2 — Account for Inflation

Inflation is the silent retirement killer. At 3% average inflation, today's $60,000 becomes $108,367 in 20 years. Always run plans in real (inflation-adjusted) terms or be explicit about inflation assumptions.

Stocks historically beat inflation by 6–7% per year long-term; bonds by 1–2%. Heavy cash positions guarantee you lose purchasing power over decades.

Step 3 — Integrate Social Security

Social Security replaces a meaningful share of pre-retirement income — roughly 40% for average earners, less for high earners. Strategies:

Claim at 62: ~30% reduction vs full benefit
Claim at FRA (66–67): 100% of benefit
Delay to 70: ~32% boost over FRA, locked in for life

For most healthy individuals, delaying to 70 is the best longevity insurance available — guaranteed 8% annual increase plus inflation adjustments.

Step 4 — Pick a Withdrawal Strategy

Static 4% rule

Simple, well-tested. Risk: doesn't react to bear markets, can deplete portfolios in poor sequences.

Dynamic withdrawals (Guyton-Klinger guardrails)

Adjust withdrawal rate up or down based on portfolio performance — typically allows higher initial rates (4.5–5%) with lower failure risk.

Bucket strategy

Split into 3 buckets: 1–2 years cash, 3–10 years bonds, 10+ years stocks. Refill from longer buckets in up markets.

Step 5 — Test Sequence-of-Returns Risk

Two retirees with the same average return can have very different outcomes if one happens to retire into a bear market. The first 5–10 years matter most. Mitigations: heavier bond allocation early in retirement, glide-path strategies, and a cash buffer for bad markets.

How Long Should Savings Last?

Plan for at least 30 years from retirement age. A couple retiring at 65 has a high probability that at least one will live past 90. Underestimating longevity is a much larger risk than over-saving.

Catch-Up Strategies After 50

If you start late, the math is steeper but not impossible.

Maximise catch-up contributions: 401(k) +$7,500/year, IRA +$1,000/year if 50+
Delay retirement 2–5 years: Doubles compounding effect, reduces years of withdrawals
Downsize housing: Free up trapped equity into income-producing investments
Aggressive savings rate: 25–35% of income for 10–15 years can produce $500k–$1M
Plan part-time income: $20,000/year reduces required portfolio by $500,000 (20× rule)

Use the Compound Interest Calculator to model catch-up scenarios and the FIRE Calculator if you want an early-retirement plan.

Common Retirement Planning Mistakes

Ignoring healthcare costs (often $300k+ for a couple over 30 years)
Underestimating taxes on traditional 401(k) withdrawals
Holding too much cash, losing real purchasing power
Failing to account for one spouse outliving the other
Claiming Social Security too early without modelling break-even
No long-term-care insurance plan

The Bottom Line

Multiply your annual retirement spending by 25 for a starter target, refine with realistic expense and inflation modelling, integrate Social Security, and run multiple withdrawal strategies. The earlier you start, the smaller the number needs to be in absolute terms — but it is genuinely never too late to improve the trajectory.