How I’d invest £5 per day in an ISA to make £500k

Investing small amounts regularly can lead to big gains. Roland Head explains how he’d invest £150 each month to build a £500k ISA.

The content of this article was relevant at the time of publishing. Circumstances change continuously and caution should therefore be exercised when relying upon any content contained within this article.

You’re reading a free article with opinions that may differ from The Motley Fool’s Premium Investing Services. Become a Motley Fool member today to get instant access to our top analyst recommendations, in-depth research, investing resources, and more. Learn More.

Saving £500,000 might feel like it’s out of reach for many of us. But I reckon I should be able to hit this target by saving as little as £5 per day, or £150 per month. In this piece I want to explain how I’d invest my cash in the stock market to build a £500k retirement fund.

How I plan to multiply my money

Although I want to build a £500k fund, I don’t intend to save £500,000 of my hard-earned cash. In fact, I only expect to have to contribute around £72,000 of my own cash to hit my goals.

The reason this is possible is because of the power of compounding. What this means is leaving any capital gains or dividend income untouched in my account and reinvesting it every year. Over time, following this approach makes a big difference to investment returns.

For example, the average long-term return from the UK stock market is about 8% per year. If I invested £1,000 at this rate and made no withdrawals, my investment would be worth £10,062 after 30 years. That’s a profit of £9,062.

However, if I withdrew the 8% return each year, my total profit would be just £2,400.

Staying with the same 8% return, my calculations show that by investing £5 per day (£150 per month) for 40 years, I should be able to build a £500,000 retirement fund.

How I’d invest the cash

There are lots of ways to invest in the stock market, but my priority is to make it simple, cheap, and reliable.

In my view, the cheapest and simplest way to invest in UK shares is to buy a FTSE 100 index fund. These low-cost funds track the progress of the FTSE 100 index, which contains the 100 largest companies on the UK stock market.

A FTSE 100 tracker fund won’t fill my life with excitement. But over long periods, history suggests that it should be reliable.

However, I can’t ignore the fact that smaller companies have earned more attractive returns over the last decade. To gain some exposure to faster-growing businesses, I’d probably put half of my cash into a FTSE 250 index fund. The FTSE 250 contains companies that are well established but a little smaller than FTSE 100 firms. Typically, FTSE 250 companies have more room left to grow.

Why I always use an ISA

I don’t mind paying tax. But the UK ISA system means that investors can invest up to £20,000 a year completely tax free. This is a no-brainer, in my view.

That’s why the first thing I did when I started investing was to open a Stocks and Shares ISA.

The £20,000 per year limit on an ISA means you can save up to £1,666 per month, tax free. That’s plenty, for most people. Indeed, my sums show that based on the 8% annual return I mentioned above, you could hit £1m in 20 years if you maxed out your ISA each month.  

Roland Head has no position in any of the shares mentioned. The Motley Fool UK has no position in any of the shares mentioned. Views expressed on the companies mentioned in this article are those of the writer and therefore may differ from the official recommendations we make in our subscription services such as Share Advisor, Hidden Winners and Pro. Here at The Motley Fool we believe that considering a diverse range of insights makes us better investors.

More on Investing Articles

Smiling black woman showing e-ticket on smartphone to white male attendant at airport
Investing Articles

Can this airline stock beat the FTSE 100 again in 2026?

After outperforming the FTSE 100 in 2025, International Consolidated Airlines Group has a promising plan to make its business more…

Read more »

Investing Articles

1 Stocks and Shares ISA mistake that will make me a better investor in 2026

All investors make mistakes. The best ones learn from them. That’s Stephen Wright’s plan to maximise returns from his Stocks…

Read more »

Portrait Of Senior Couple Climbing Hill On Hike Through Countryside In Lake District UK Together
Investing Articles

I asked ChatGPT if £20,000 would work harder in an ISA or SIPP in 2026 and it said…

Investors have two tax-efficient ways to build wealth, either in a Stocks and Shares ISA or SIPP. Harvey Jones asked…

Read more »

Investing Articles

How much would I need invested in an ISA to earn £2,417 a month in passive income?

This writer runs the numbers to see what it takes in an ISA to reach £2,417 a month in passive…

Read more »

Investing Articles

Rolls-Royce shares or Melrose Industries: Which one is better value for 2026?

Rolls-Royce shares surged in 2025, surpassing most expectations. Dr James Fox considers whether it offers better value than peer Melrose.

Read more »

Investing Articles

3 top Vanguard ETFs to consider for an ISA or SIPP in 2026

Edward Sheldon believes that these three Vanguard ETFs could be solid investments for a pension (SIPP) or investment account in…

Read more »

Investing Articles

5 growth stocks on Dr James Fox’s watchlist for 2026

Dr James Fox believes these UK and US growth stocks are worth considering as he looks to outperform the stock…

Read more »

Pink 3D image of the numbers '2025' growing in size
Investing Articles

Meet the 6p penny stock that has smashed Nvidia in 2025

This UK penny stock has surged around 70% in 2025, outperforming most other companies. But why is it such a…

Read more »