Retirement Planning: How Much Do You Really Need to Save?

The Retirement Planning Problem

Most people avoid thinking seriously about retirement because the numbers seem overwhelming. But the alternative — reaching your 60s with insufficient savings — is far worse.

The good news: retirement planning is not complicated. It requires understanding a few key concepts, honest assessment of where you stand, and consistent action over time. Use our Retirement Calculator to find out where you stand right now.

Step 1: Know Your Retirement Number

Your retirement number is the total amount you need saved to fund your retirement. The most widely used method to calculate it is the 4% rule.

The 4% Rule Research from Trinity University found that a retiree could withdraw 4% of their portfolio in year one, then adjust for inflation each subsequent year, and have a very high probability of the money lasting 30 years.

To find your retirement number using the 4% rule:

• Estimate your annual retirement spending
• Divide by 0.04 (or multiply by 25)

Examples:

• Spend £30,000/year in retirement: need £750,000
• Spend £40,000/year: need £1,000,000
• Spend £50,000/year: need £1,250,000
• Spend £60,000/year: need £1,500,000

This is your target retirement number.

Step 2: Account for Other Income Sources

Your retirement number does not need to come entirely from personal savings. Deduct guaranteed income sources:

State Pension (UK) The full new State Pension is currently £11,502 per year (2024/25). To qualify for the full amount you need 35 qualifying National Insurance years. Check your State Pension forecast at gov.uk/check-state-pension.

At 4%, £11,502 per year in State Pension is equivalent to having £287,550 in your retirement pot.

Defined Benefit Pension If you have a final salary or career average pension from an employer, this provides guaranteed income. Subtract the annual income it provides from your spending target before applying the 4% rule.

Example:

• Target retirement spending: £40,000/year
• State Pension: £11,502/year
• Employer DB pension: £8,000/year
• Income gap: £40,000 − £11,502 − £8,000 = £20,498/year
• Retirement number needed: £20,498 ÷ 0.04 = £512,450

Step 3: Calculate How Much to Save Monthly

Once you know your retirement number and your current savings, our Retirement Calculator tells you the monthly contribution needed to reach your goal.

The general formula if you want to do it manually:

Monthly contribution = (Target − Current savings × growth factor) ÷ ((growth factor − 1) ÷ monthly rate)

In practice, the calculator handles this for you.

General benchmarks by age (assuming 7% return, retiring at 65):

• Age 25, £0 saved: save approximately 10–15% of gross income
• Age 30, £20,000 saved: save approximately 12–18% of gross income
• Age 35, £50,000 saved: save approximately 15–20% of gross income
• Age 40, £100,000 saved: save approximately 20–25% of gross income
• Age 45, £150,000 saved: save approximately 25–35% of gross income
• Age 50, £200,000 saved: save approximately 35–50% of gross income

What Return Should You Assume?

Choosing the right assumed return is critical — too optimistic and you will undersave; too pessimistic and you may save more than necessary.

7% per year is a commonly used assumption for a diversified portfolio of stocks and bonds, representing long-term real returns after inflation.

5% per year is more conservative and appropriate if you hold significant bonds or are closer to retirement.

4% per year is appropriate for very conservative investors or those within 10 years of retirement.

Our Retirement Calculator uses 7% as the default but you can adjust it to test different scenarios.

The Impact of Starting Age

Starting earlier is the most powerful lever in retirement planning.

To accumulate £500,000 by age 65 (assuming 7% return):

• Starting at 25: need to save £213/month (total contributions: £102,240)
• Starting at 30: need to save £313/month (total contributions: £112,680)
• Starting at 35: need to save £467/month (total contributions: £121,420)
• Starting at 40: need to save £713/month (total contributions: £128,340)
• Starting at 45: need to save £1,126/month (total contributions: £135,120)
• Starting at 50: need to save £1,944/month (total contributions: £139,968)

Waiting from age 25 to 35 costs you an extra £254/month for the same outcome. Waiting from 25 to 45 costs you an extra £913/month.

What If You Are Behind?

Most people feel behind on retirement saving at some point. Here are the practical options:

Increase contributions immediately Even a small increase compounded over years makes a significant difference. An extra £100/month started at age 40 adds approximately £122,000 to your pot by 65 at 7% return.

Delay retirement Working 2–3 additional years has a double benefit: more years of contributions and compound growth plus fewer years of drawdown. Even working part-time in early retirement can dramatically extend how long your savings last.

Reduce retirement spending target Honest assessment of what you actually need in retirement often reveals the target is lower than feared. Many people find their spending naturally decreases in retirement — mortgages are paid off, children are independent, commuting costs disappear.

Take advantage of employer matching If your employer matches pension contributions and you are not contributing enough to get the full match, you are leaving free money on the table. This is the highest guaranteed return available to you.

Maximise tax-advantaged accounts In the UK, pension contributions receive tax relief at your marginal rate. A higher rate taxpayer investing £100 into a pension costs them only £60 after 40% tax relief — a 67% instant return before investment growth.

Common Retirement Planning Mistakes

Overestimating State Pension income Many people assume the State Pension will cover most of their retirement costs. At £11,502 per year, it covers basic living costs in some regions but is insufficient for a comfortable retirement in most of the UK.

Cashing out pensions when changing jobs Taking pension funds as cash when you leave an employer incurs tax charges and permanently removes that money from compounding. Always transfer to a new pension instead.

Being too conservative with investments Young savers often hold too much cash or bonds out of caution. Over a 30-year horizon, the inflation risk of being too conservative far outweighs the volatility risk of holding equities. Time in the market matters more than timing the market.

Not increasing contributions with salary rises A simple rule: when you get a pay rise, increase your pension contribution by at least half the raise. You were living fine without the extra money — redirect part of it to your future self.

Underestimating retirement duration A 65-year-old in the UK has an average life expectancy of roughly 85–87. But averages mean half of people live longer. Plan for 25–30 years of retirement, not 15–20.

Frequently Asked Questions

• How much should I have saved by 40?

A common benchmark is 3× your annual salary by age 40. If you earn £40,000, target £120,000 in retirement savings by 40. This is a guideline, not a rule — use our Retirement Calculator for a personalised number.

• Is it too late to start saving for retirement at 50?

It is never too late. Starting at 50 with 15 years to retirement at 7% return, £500/month in contributions grows to approximately £160,000 — plus whatever State Pension and other income you have. It is less than starting at 30 but significantly better than not starting.

• What is a good monthly retirement income?

According to the PLSA Retirement Living Standards, a moderate retirement standard in the UK requires approximately £31,300 per year for a single person (2023 figures). A comfortable retirement standard requires approximately £43,100 per year.

• Should I pay off my mortgage or save for retirement?

Generally, if your employer offers pension matching, contribute enough to get the full match first — it is a guaranteed 100% return. After that, compare your mortgage interest rate to your expected investment return. If your mortgage rate is below 5%, investing is usually better mathematically. Above 5–6%, paying off the mortgage provides a better guaranteed return.

• Can I retire early?

Early retirement is possible with higher savings rates and realistic spending targets. The FIRE movement (Financial Independence, Retire Early) typically targets a 25× annual spending portfolio with a 4% withdrawal rate. Use our Retirement Calculator to model different retirement ages.