UK Pension Pot Calculator 2026/27

How It Works

A workplace pension pot grows from three sources at once: your contributions, your employer’s contributions and tax relief — all invested, so growth compounds on top. The projection uses the standard future-value formula with monthly compounding: your current pot grows at the assumed annual rate divided by 12, and each month’s total contribution is added at month-end and compounds for the remaining months. In symbols, the projected pot is P × (1 + r/12)^12t + M × [((1 + r/12)^12t − 1) / (r/12)], where P is your current pot, M is the total monthly amount into the pot, r is the annual growth rate and t is the years to retirement.

Tax relief is what makes a pension different from an ordinary savings account: the government refunds the income tax on the money you contribute, at your marginal rate. Under relief at source, your contribution comes from take-home pay and the provider claims 20% basic-rate relief from HMRC — £80 from your pay becomes £100 in your pension. Higher-rate (40%) and additional-rate (45%) taxpayers claim the extra relief through Self Assessment; it comes back as cash, so this calculator shows it separately. Under net pay, the contribution is taken before tax, so the full amount goes in and you get relief at your marginal rate automatically. Most workplace pensions use net pay; most personal pensions use relief at source.

Auto-enrolment sets the floor. If you are aged 22 to State Pension age and earn over £10,000 a year from one employer, your employer must enrol you and contribute. The legal minimum is 8% of qualifying earnings — pay between £6,240 and £50,270 a year in 2026/27 — with at least 3% from the employer and 5% from you, including tax relief. Many employers pay more than the minimum, so check your payslip rather than assuming the minimum.

There is also a ceiling. The annual allowance is £60,000 for 2026/27: the most that can go into all your pensions in one tax year with full tax relief, counting your contributions, your employer’s and tax relief together. Above it, the excess faces a tax charge at your marginal rate. Very high earners face a tapered allowance — it falls by £1 for every £2 of adjusted income above £260,000, down to a minimum of £10,000 — and once you have flexibly accessed a pension, the money purchase annual allowance caps further saving at £10,000 a year. This calculator flags it if your annual contributions pass £60,000, but it does not model the taper.

Retirement income is shown two ways. The monthly income from your pot uses the 4% rule: withdraw 4% of the pot in the first year of retirement and divide by 12. It is a widely used rule of thumb, not a promise — how long a pot lasts depends on actual returns, inflation and how long you live. On top of that comes the State Pension: the full new State Pension is £241.30 a week in 2026/27 (£12,547.60 a year, about £1,045.63 a month), and you normally need 35 qualifying years of National Insurance for the full amount. You can also usually take up to 25% of your pot as a tax-free lump sum, capped at £268,275.

Worked example: a £20,000 current pot, £200 a month from you and £150 a month from your employer, relief at source as a basic-rate taxpayer, 5% annual growth and 30 years to retirement. Relief at source turns your £200 into £250 in the pot (£200 ÷ 0.8), so £400 a month goes in altogether. Over 30 years at 5% compounded monthly, the pot grows to a projected £422,258.34. You will have paid in £164,000 in total (£20,000 + £400 × 360), so investment growth adds £258,258.34. The 25% tax-free lump sum would be £105,564.59, the 4% rule gives £1,407.53 a month from the pot, and adding the full new State Pension (about £1,045.63 a month) gives a total monthly retirement income of about £2,453.16.

Two percentage points of growth more than doubles the pot — which is why the growth rate you assume matters more than almost any other input.

Assumptions

• Constant growth, no fees. One annual growth rate applies for the whole period, compounded monthly, with no fund charges, platform fees or inflation adjustment. Real returns vary and charges reduce the pot.
• Contributions stay flat. Monthly contributions do not rise with pay or inflation, and no lump sums are added later.
• Relief at source adds 20% to the pot. Your net contribution is grossed up by dividing by 0.8; extra higher-rate or additional-rate relief is shown separately because you reclaim it yourself. Under net pay the contribution enters the pot in full and no top-up is added.
• Annual allowance check is the standard £60,000. The tapered allowance for high earners and the £10,000 money purchase annual allowance are not modelled.
• The 4% rule is a rule of thumb. It is not a guaranteed sustainable withdrawal rate, and the income shown is before tax on withdrawals above the tax-free lump sum.

Sources: GOV.UK — Workplace pensions: what you, your employer and the government pay; GOV.UK — Tax on your private pension contributions; GOV.UK — The new State Pension: what you’ll get; DWP — Benefit and pension rates 2026 to 2027. Figures checked 13 November 2026.

Built and tested by SumKitTool — see how we check our numbers.

How to Use This Calculator

Start with your current pot — the total across all your defined contribution pensions. Then enter what you and your employer pay in each month; both figures appear on your payslip. Choose how tax relief is given: relief at source if your provider adds the 20% top-up, net pay if your contribution comes off before tax. If you are unsure, your scheme booklet or HR team can confirm it.

Next, set your marginal tax rate — the rate on your top slice of income — then the assumed annual growth and the years until you plan to retire. The growth rate is the biggest unknown in the projection, so try it at 3%, 5% and 7% and compare the results. Finally, check the State Pension figure: the default is the full new State Pension for 2026/27 (£241.30 a week), but your own amount depends on your National Insurance record. Results update as you type.

Tips and Practical Advice

Never turn down free employer money. If your employer matches extra contributions, every pound you add can be doubled before tax relief and growth even start. At the very least, make sure you are getting the full employer contribution on offer; opting out of auto-enrolment means giving up the employer’s 3% as well as the tax relief.

Claim the extra relief if you are a higher-rate taxpayer in a relief-at-source scheme. The provider only adds basic-rate relief automatically; the extra 20% (or 25% for additional-rate taxpayers) comes back through Self Assessment, and it is easy to miss year after year. In a net pay scheme the full relief happens on your payslip and there is nothing to claim.

Start early rather than saving more later. Growth compounds, so money paid in during your twenties and thirties has decades to multiply — in the worked example, growth adds more than the contributions themselves over 30 years. A smaller contribution started now usually beats a larger one started ten years later.

Check your State Pension forecast: the full new State Pension is worth about £1,045.63 a month in 2026/27, but only with the qualifying years behind you. And if you are a high earner, remember the £60,000 annual allowance — unused allowance can sometimes be carried forward from the previous three years.

Frequently Asked Questions