Required Lumpsum Calculator UK
Find the one-time investment needed today to reach a future financial goal.
How it works
Compound interest earns returns on both your original money and the returns already added. Adding a regular monthly contribution accelerates growth further over time.
A = P(1 + r/n)^(nt) + contributions compounded monthly- Longer time horizons benefit most from compounding
- More frequent compounding gives slightly higher growth
- The donut shows how much of your final balance is interest vs money you put in.
Frequently asked questions
How much lump sum do I need to reach a goal?
Divide the future goal by (1 + return)^years. For £50,000 in 10 years at 7%, that is about £25,415 today.
What is present value?
The amount today equivalent to a future sum, given a rate of return — the lump sum that grows into your goal.
What return rate should I assume?
A realistic expected return for your investments, remembering returns are not guaranteed, so test a few rates.
Why does a longer horizon lower the required lump sum?
Because the money has more time to compound, so a smaller amount can grow into the same goal.
Does inflation affect this?
Yes. If your goal is in today’s money, build in inflation, since future purchasing power is lower than the nominal figure.
Can I shelter the growth from tax?
Within an ISA, up to £20,000 a year, growth is free of UK Income and Capital Gains Tax, improving the net outcome.
The lump sum you need to invest today
This calculator finds the single amount to invest now to reach a future goal, given an expected return. It is a present-value calculation: PV = FV / (1 + r)^t, where FV is the goal, r the annual return and t the years.
Worked example
To have £50,000 in 10 years at a 7% annual return, you would need to invest 50,000 / 1.07^10 ≈ £25,415 today. The rest — nearly £25,000 — comes from compound growth on that lump sum.
What moves the number
A higher expected return or a longer horizon both reduce the lump sum required, because compounding does more of the work. A shorter horizon or lower return means you must invest more upfront to hit the same target.
Returns are not guaranteed and inflation erodes future value, so treat the figure as a planning estimate. Tax-efficient wrappers such as ISAs can shelter the growth. For decisions, consider regulated financial advice.
Results are estimates for general guidance in United Kingdom and may not reflect the latest local rates, fees or rules. Check official sources before making decisions.