Five years is a common planning horizon for house deposits, car savings, career break funds, and other medium-term goals. At £300/month with 5% returns (a reasonable assumption for balanced or lower-risk investments), you'd accumulate approximately £20,400 — with £18,000 contributed and £2,400 in interest. Over shorter periods, conservative rate assumptions are usually wiser, since you have less time to recover from a market downturn. Cash ISAs, premium bonds, or a 60/40 stock-bond portfolio are common choices for 5-year horizons.
Illustrative estimate only — not a guarantee
~£21,685 after 5 years
£19,000 contributed + £2,685 interest
Based on a hypothetical constant return. Actual returns will vary.
By the CompoundWise Team · Updated April 2026
UK-based financial education · Not financial advice
Invest £300/month for 5 years at 5%
£2,685
earned in interest alone
Total value
£21,685
You put in
£19,000
To reach £21,685, most UK investors use a Stocks & Shares ISA

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Compare other platforms ↓Keeping this in a savings account? You'd have ~£576 less
Compared to investing at 5% vs a 4% cash savings account

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With a £1,000 starting balance and £300 per month at 5% returns, your first year ends at approximately £4,730 — £4,600 contributed and £130 in interest. Year two brings roughly £8,570, with cumulative interest reaching approximately £370. By year three, your balance hits about £12,530 and interest earned in that single year exceeds £510. Year four delivers approximately £16,620, and by the end of year five, you reach roughly £20,400. Your total contributions are £19,000 (£1,000 lump sum plus £18,000 in monthly payments), with approximately £1,400 earned through compound interest. While £1,400 may seem modest, it represents money earned with zero effort — and in a tax-free ISA wrapper, every penny is yours.
Five years is too short for an aggressive equity strategy — a single bad year could leave you below your target when you need the money. Conservative and balanced approaches are more appropriate. Option one: cash ISA at 4% to 5% — fully predictable, FSCS protected, zero risk of capital loss. Option two: premium bonds — tax-free prizes at an effective rate around 4% to 4.5%, with the chance of larger wins. Option three: a balanced multi-asset fund (40% to 60% equities, remainder in bonds and cash) inside a stocks and shares ISA — higher expected return than cash, but with some volatility risk. Option four: short-dated UK gilt funds — very low risk with returns roughly tracking the Bank of England base rate. For money you absolutely need in five years (like a house deposit), lean toward options one or two.
Define your specific goal: house deposit, car fund, career break, or wedding savings. Calculate the target amount and use the calculator above to confirm £300 per month at your chosen return rate gets you there. Open the appropriate account — a cash ISA for maximum safety, or a stocks and shares ISA for potentially higher returns with some volatility risk. Set up your £300 monthly direct debit on payday. If you have the £1,000 lump sum available, invest it immediately to give compound interest the largest base from day one. Review your progress every six months rather than monthly — over five years, you want steady progress, not daily anxiety. As you approach the final 12 months, consider moving into cash or a money market fund to lock in your gains and eliminate the risk of a last-minute market dip.
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