You can start investing with £100 in the UK, and most investment platforms let you buy funds through a Stocks and Shares ISA with that amount or less. What makes the real difference is whether it is a one-off or a regular habit. At an illustrative 5% a year after fees, £100 invested once grows to about £163 in ten years, while £100 a month grows to about £15,500.
This guide compares the two approaches, shows why fee structure matters more than usual at small amounts, and walks through the first steps. For a broader beginner's walkthrough, see our guide to starting to invest with £100.
Check you are ready to invest
Investing makes sense for money you can leave alone for at least five years, because share prices can fall sharply in the short term. Before you start, make sure you have:
- No expensive debt such as credit cards or overdrafts, which usually cost more than investments are likely to earn
- An emergency fund in easy-access savings; our emergency fund calculator suggests a target
- Your workplace pension running, especially if your employer matches contributions
- Money set aside for anything you need within five years, such as a house deposit
£100 once vs £100 a month
The table uses an illustrative 5% a year return after fees. Real returns vary year to year and can be negative; this is not a forecast.
| Approach | Paid in | After 10 years | After 20 years |
|---|---|---|---|
| £100 once | £100 | About £163 | About £265 |
| £100 a month | £12,000 / £24,000 | About £15,500 | About £41,100 |
A single £100 is a good way to learn how a platform works and to get used to seeing values go up and down. The money that changes your future comes from the habit. Try your own figures in our investment calculator or compound interest calculator.
Why fees matter more at small amounts
Platforms charge in two main ways, and the right one depends on the size of your pot.
- Percentage fees take a share of what you hold each year. They stay small in pounds when your pot is small, which suits beginners
- Flat fees charge a fixed amount per month whatever you hold. They suit large pots but can be expensive at the start
- Fund charges (the ongoing charges figure, or OCF) are paid on top of the platform fee. Index funds usually have low charges
- Dealing fees apply when you buy or sell. Many platforms offer free regular investing into funds
A fee example on a small pot
Take a hypothetical pot of £1,200, roughly what you would have after a year of £100 a month. These are example charges for illustration, not any provider's actual prices.
| Fee type | Example charge | Yearly cost on £1,200 |
|---|---|---|
| Percentage | 0.25% a year | £3 |
| Flat | £4 a month | £48 (4% of the pot) |
A 4% charge would wipe out most of a typical year's growth. Once your pot reaches tens of thousands of pounds, a flat fee can become the cheaper option, so review this as you grow. Comparison tables from Which? and MoneySavingExpert list current platform charges.
What to invest your £100 in
For most beginners, a single low-cost global index fund or a ready-made multi-asset fund is a sensible starting point. A global index fund spreads your money across thousands of companies in many countries, so you are not relying on any one business. Ready-made funds also hold bonds, which makes them less volatile, and the provider rebalances for you.
Picking individual shares with £100 is possible through fractional shares, but your money is concentrated in very few companies. Our guide to index fund investing explains the options.
How to start, step by step
Getting started usually takes under half an hour.
- Choose a platform with a percentage fee or low minimums suited to small pots
- Open a Stocks and Shares ISA, so all growth and income is tax-free. You must be 18 or over and UK resident, and you can pay in up to £20,000 a year across all your ISAs
- Pay in your £100 and choose a fund, or set up a £100 monthly direct debit
- Turn on automatic investing so each payment buys more of the fund
- Leave it alone and check once or twice a year, not daily
Is your money protected?
If an FCA-authorised platform fails, your investments should be held separately and returned to you. If anything is missing, the FSCS can usually compensate up to £85,000 per person per firm. The FSCS does not protect you against investments falling in value. Read what a Stocks and Shares ISA is for more on how the wrapper works.
If you are building the habit of putting money aside before you invest, SYM can help: it suggests a small amount to save each day until you have enough for your next monthly investment.
Frequently asked questions
Is it worth investing £100?
What is the best way to invest £100 a month in the UK?
Can I lose money investing £100?
Do I pay tax on investment gains in the UK?
Should I invest £100 or save it?
- investing for beginners
- Stocks and Shares ISA
- index funds
- platform fees
- monthly investing