How to invest £100 a month in the UK (and what it could grow to)
A simple plan to start investing £100 a month: which account to use, what to invest in, keeping fees low, and how much £100 a month could grow to over 10, 20 and 30 years.
By SimonIn this guideShowHide
£100 a month is a great amount to start with. It is small enough to keep going in a tight month, and big enough to grow into something meaningful over time.
Before you start
Investing is for money you will not need for at least five years. First:
- Clear expensive debts like credit cards. See how to pay off debt faster.
- Have an emergency fund in cash.
- Get your full employer pension match if you have a job. It is free money.
Step 1: open a stocks and shares ISA
An ISA means no tax on growth or income, ever, and you do not need to put it on a tax return. You can put up to £20,000 a year into ISAs. Read stocks and shares ISAs explained.
If you are 18 to 39 and saving for a first home, a Lifetime ISA adds a 25% bonus.
Step 2: choose a low-cost platform
On a small monthly amount, fees matter. A £4 monthly fee is 4% of a £100 payment. Look for:
- No platform fee, or a low percentage fee
- Free regular investing
- Access to the index funds or ETFs you want
Compare the options in my investing apps guide.
Step 3: pick what to invest in
For most beginners, one fund is enough: a global index fund or ETF that holds thousands of companies around the world. It spreads your risk, and fees are often well under 0.25% a year.
Avoid putting your monthly £100 into a handful of individual shares or whatever is trending on social media. Read index funds and ETFs explained.
Step 4: automate it
Set up a monthly direct debit for the day after payday, and tell the platform to invest it automatically. This is called pound-cost averaging: you buy more when prices are low and less when they are high, and you never have to decide when to invest.
What £100 a month could grow to
| Years | Paid in | At 3% a year | At 5% a year | At 7% a year |
|---|---|---|---|---|
| 5 | £6,000 | £6,458 | £6,781 | £7,120 |
| 10 | £12,000 | £13,945 | £15,436 | £17,105 |
| 20 | £24,000 | £32,685 | £40,580 | £50,754 |
| 30 | £36,000 | £57,871 | £81,538 | £116,945 |
Growth rates are after fees and before inflation. They are illustrations, not forecasts. Investments can fall, especially in the short term.
Free toolCompound interest calculatorSee how a lump sum and monthly savings could grow over time, and how much fees cost you.Ways to boost it
- Increase it with every pay rise. Even £10 more a month adds up.
- Add side hustle income. Put a share of every payment straight in. Here are side hustle ideas.
- Invest windfalls like a bonus or a tax refund.
Common questions
Is £100 a month worth investing?
Yes. Starting small and early often matters more than the amount. Over 30 years, the growth on £100 a month can be bigger than the amount you put in.
Should I save or invest £100 a month?
Save if you need the money within five years or have no emergency fund. Invest if it is for the long term and you can leave it alone through ups and downs.
Can I lose money investing £100 a month?
Yes, the value can fall, and you could get back less than you put in, especially over short periods. A diversified fund held for many years has historically recovered from falls, but there is no guarantee.
This is general information, not personal tax or financial advice. Tax rules change and depend on your circumstances, so check GOV.UK or speak to an accountant before acting.
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