Free calculator
Step-Up Investment Calculator
A step-up plan increases your monthly investment by a fixed percentage every year — matching pay rises and compounding faster. See how much more you accumulate compared to investing a flat amount.
Your inputs
ISA tip: The annual ISA allowance is £20,000. At your current monthly amount of £500/mo (£6,000/yr), you are within the ISA limit.
With step-up (10%/yr)
Total invested
£343.6k
Est. returns
£315.7k
Total corpus
£659.3k
Without step-up (flat £500/mo)
Total invested
£120.0k
Est. returns
£174.5k
Total corpus
£294.5k
Step-up builds £364.8k more than investing flat
+124%Year-by-year breakdown
| Year | Monthly (start) | Total invested | Step-up corpus | Flat corpus | Difference |
|---|---|---|---|---|---|
| 1 | £500 | £6.0k | £6.2k | £6.2k | +£0 |
| 2 | £550 | £12.6k | £13.6k | £13.0k | +£622 |
| 3 | £605 | £19.9k | £22.2k | £20.3k | +£2.0k |
| 4 | £666 | £27.8k | £32.4k | £28.2k | +£4.2k |
| 5 | £732 | £36.6k | £44.2k | £36.7k | +£7.4k |
| 6 | £805 | £46.3k | £57.9k | £46.0k | +£11.9k |
| 7 | £886 | £56.9k | £73.7k | £56.1k | +£17.7k |
| 8 | £974 | £68.6k | £92.0k | £66.9k | +£25.0k |
| 9 | £1,072 | £81.5k | £112.9k | £78.7k | +£34.2k |
| 10 | £1,179 | £95.6k | £137.0k | £91.5k | +£45.5k |
| 11 | £1,297 | £111.2k | £164.5k | £105.3k | +£59.2k |
| 12 | £1,427 | £128.3k | £195.9k | £120.3k | +£75.7k |
| 13 | £1,569 | £147.1k | £231.7k | £136.5k | +£95.2k |
| 14 | £1,726 | £167.8k | £272.4k | £154.0k | +£118.4k |
| 15 | £1,899 | £190.6k | £318.7k | £173.0k | +£145.7k |
| 16 | £2,089 | £215.7k | £371.1k | £193.6k | +£177.5k |
| 17 | £2,297 | £243.3k | £430.5k | £215.9k | +£214.6k |
| 18 | £2,527 | £273.6k | £497.7k | £240.0k | +£257.7k |
| 19 | £2,780 | £307.0k | £573.7k | £266.2k | +£307.5k |
| 20 | £3,058 | £343.6k | £659.3k | £294.5k | +£364.8k |
What is a step-up investment plan?
A step-up plan increases your monthly investment by a fixed percentage each year. For example, starting at £500/mo with a 10% annual step-up means you invest £550/mo in year two, £605/mo in year three, and so on. It mirrors typical salary growth and puts more money to work as you earn more.
Why does it outperform a flat plan?
Compounding rewards larger sums invested earlier. By stepping up each year, your total invested amount grows, and each additional pound enters the market earlier than it would if you waited until you felt "ready" to increase contributions.
How to use this with a Stocks & Shares ISA
The annual ISA allowance is £20,000. Returns inside an ISA are completely free of UK income tax and capital gains tax. If your step-up plan keeps you within £20,000/yr, all projected returns in this calculator could be tax-free.
What return rate should I use?
The UK stock market (FTSE All-World or global index funds) has returned roughly 7–10% annually over long periods before inflation. After UK CPI (~2.5%), a real return of 5–7% is a common planning assumption. Be conservative — 7% is reasonable for 20+ year horizons.
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Start free — no card needed →Projections are illustrative only. Investment returns are not guaranteed. Not financial advice.