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How to Calculate Your Retirement Savings Goal
Published Apr 17, 2026
Retirement planning requires estimating two things: how much you'll spend in retirement and how long your savings need to last. Getting these numbers right early gives you the most time to act.
Step 1 — Estimate Your Annual Retirement Spending
Most financial planners use 70–80% of pre-retirement income as a starting estimate, because:
- Mortgage is usually paid off
- Children are financially independent
- Work-related expenses disappear
- Taxes may be lower
Example: If you currently earn £60,000/year, estimate £42,000–£48,000/year in retirement.
Adjust up if you plan travel, healthcare costs, or major hobbies. Adjust down if you'll have a paid-off home and modest lifestyle.
Step 2 — Apply the 4% Rule (Safe Withdrawal Rate)
The 4% rule states that you can withdraw 4% of your portfolio in the first year of retirement and adjust for inflation annually — with a high probability your portfolio will last 30+ years.
Required savings = Annual spending ÷ 0.04
= Annual spending × 25
Example: £42,000/year → £42,000 × 25 = £1,050,000 required
This is a rough rule. If you retire at 55 and may live 40+ years, consider using 3.5% (× 28.6). If you retire at 70, 4.5% (× 22) may be appropriate.
Step 3 — Account for Other Income Sources
Reduce your required savings by guaranteed income sources:
| Source | Example |
|---|---|
| State Pension (UK) | ~£11,500/year (full new state pension 2026) |
| Social Security (US) | Varies; average ~$22,000/year |
| Defined-benefit pension | Check your annual statement |
| Rental income | Net rent after costs |
Example: £42,000 needed − £11,500 state pension = £30,500 needed from savings Required portfolio = £30,500 × 25 = £762,500
Step 4 — Account for Inflation
£42,000 today will buy less in 20 years. Inflation erodes purchasing power at roughly 2–3% per year.
Future spending at 2.5% inflation:
Future value = Today's spending × (1 + 0.025)^years
Example: £42,000 today, retiring in 25 years:
42,000 × (1.025)^25 = 42,000 × 1.853 = £77,826/year needed
Your required portfolio also needs to be inflation-adjusted. Most retirement calculators handle this automatically by projecting real (inflation-adjusted) returns.
Step 5 — Calculate Monthly Savings Needed
If you're starting from zero and targeting a specific corpus:
Monthly saving = FV × r / [(1 + r)^n − 1]
Where FV = target amount, r = monthly return rate, n = months.
Example: Target £762,500 in 25 years, assuming 6% annual return:
- r = 0.06/12 = 0.005
- n = 300
- Monthly saving ≈ £1,110/month
Common Retirement Planning Mistakes
- Starting too late. Compound growth needs time; 10 extra years of contributions makes a dramatic difference.
- Underestimating healthcare costs. Medical expenses often increase in retirement.
- Forgetting inflation. A fixed pension that looked generous at 65 may feel meagre at 80.
- Withdrawing too early from tax-advantaged accounts. Penalties and tax costs can be significant.
- Assuming stock returns will be constant. Sequence-of-returns risk (bad years at the start of retirement) can deplete a portfolio faster than averages suggest.
Use the Retirement Calculator to model your target age, savings rate, and expected returns in one place.