How does monthly compounding differ from annual?

Monthly compounding calculates interest 12 times per year instead of once. Your returns start earning their own returns sooner, which produces a slightly higher final balance. The difference is modest but grows over long time periods.

Is it better to invest a lump sum or monthly?

Statistically, lump sum investing wins about two-thirds of the time because markets tend to rise. But monthly investing (pound-cost averaging) reduces timing risk and is more practical for most people who invest from their salary.

How much should I invest each month?

A widely-used guideline is to save 20% of your after-tax income. But any consistent amount helps — even £50/month grows to ~£40,000 over 25 years at 7%. The most important factor is starting and maintaining the habit.

What happens if I miss a month?

Missing occasional months has minimal impact on long-term results. What matters is the overall consistency. If you contribute 11 out of 12 months per year, you'll still capture the vast majority of compound growth.

Can I change my monthly contribution amount over time?

Yes — and you should. Use the Advanced Settings to model annual contribution increases. Raising your contribution by even 3–5% per year (perhaps matching pay rises) dramatically improves your long-term outcome.

Monthly Contributions

Monthly Compound Interest
Calculator

See how small monthly savings can grow into life-changing money

Discover how powerful regular monthly saving really is. Even small amounts grow into substantial sums when you invest consistently over time.

Free to useNo signup requiredUsed by UK investors

1Calculate

2Understand

3Take action

Starting amount

£0£20k£200k

Monthly contribution

£0£1k£5k

Expected annual return

Time horizon

yrs

Final Balance

£243,022

After 25 years

You Put In

£90,000

Your own money

Interest Earned

£153,022

Earned passively

You could reach £243,022 — investing tax-free can help you get there

Your money vs compound growth63% from interest

ContributionsCompound interest

To reach £243,022, most UK investors use a Stocks & Shares ISA to invest £300/month tax-free.

Returns depend on the underlying investments and are not guaranteed.

Your £300/month fits within the £20,000 ISA allowance

All growth inside an ISA is tax-free. Start from as little as £1.

Capital at risk when investing

Thousands of UK investors use this calculator monthly

Start investing tax-free ↓

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See how different choices change your outcome

Growth Over Time

Quick Scenarios

Your Personalised Insights

Year 19: your interest overtakes your contributions. From here, compounding does the heavy lifting.
Your money earns ~£17/day in interest — that's £153,022 earned while you sleep.
Saving just £50 more per month would add £40,503 to your final balance — that's £15,000 invested for £40,503 extra.
5 more years would add £122,969 — nearly 51% more, showing how powerful time is.
Starting 5 years earlier would add £86,744 to your final balance. Every year you wait costs real money.Start investing now →
Consistency beats timing — investing £300/month for 25 years matters more than picking the perfect moment to start.
At your current plan, you reach £100k in 16 years. That's a real milestone — and it compounds from there.Start building towards it →

Next Steps

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Explore popular UK investment platforms

Many UK investors hold investments in a stocks & shares ISA for tax efficiency. Returns depend on the investments held within the ISA and are not guaranteed. Here are popular platforms available to UK investors.

FCA regulatedFree to openTax-free ISA growth

Platform	Min. invest	Fees	ISA	Best for
Trading 212	Start from £1	No commission	Yes	Beginner-friendly
Revolut	No minimum	Free plan available	Yes	All-in-one finance
Estateguru	Start from €50	No investor fees	—	Property-backed lending

Trading 212

Suited for: Beginner-friendly

Commission-free stocks & shares ISA. Clean app, no hidden charges, perfect for getting started.

Most popular choice for UK investors starting small

No commission on stocks1M+ UK usersFree ISA included

No commissionStart from £1FCA regulatedGet started free →

All-in-one appAffiliate

Revolut

Suited for: All-in-one finance

All-in-one finance app with savings vaults, stock trading, crypto, and multi-currency accounts. Great for everyday money management.

40M+ global usersInstant account setupSavings + investing in one app

Free plan availableNo minimumFCA regulatedGet started free →

Property-backed lendingAffiliate

Estateguru

Suited for: Property-backed lending

European property-backed lending platform. Returns are not guaranteed and your capital is at risk. Past performance is not a reliable indicator of future results.

Property-secured loansAuto-invest available

P2P lending is high risk. You could lose some or all of your money. Not covered by the FSCS.

No investor feesStart from €50Licensed by Estonian Financial Supervision AuthorityGet started free →

Capital at risk. These are informational suggestions, not financial advice.

Invest from £1 tax-free

Capital at risk

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Try These Scenarios

What If You Invest £100 Per Month?See how investing £100 per month grows over time with compound interest. Calculate your projected returns with our free tool.Invest £300 Per Month — How Much Will It Grow?See how £300 monthly investments compound over 10, 20, or 30 years. Visual calculator with insights and year-by-year projections.Invest £500 Per Month — Long-Term Growth CalculatorSee how £500 monthly investments compound over time. Visualise your potential returns with charts and year-by-year breakdown.

Explore All Scenarios

Browse pre-built calculators by category.

What If You Invest £50 Per Month?See how even £50 per month compounds into real wealth over time. Free calculator with visual charts and year-by-year breakdown.What If You Invest £100 Per Month?See how investing £100 per month grows over time with compound interest. Calculate your projected returns with our free tool.Invest £200 Per Month — Compound Growth ProjectionCalculate how £200 monthly contributions grow with compound interest over 10, 20, or 30 years. Free visual calculator.Invest £300 Per Month — How Much Will It Grow?See how £300 monthly investments compound over 10, 20, or 30 years. Visual calculator with insights and year-by-year projections.Invest £500 Per Month — Long-Term Growth CalculatorSee how £500 monthly investments compound over time. Visualise your potential returns with charts and year-by-year breakdown.Invest £750 Per Month — Wealth Projection CalculatorCalculate how £750 per month compounds over time. See projected balances, interest earned, and milestone years.Invest £1,000 Per Month — Wealth Building CalculatorCalculate how investing £1,000 per month compounds over time. See projected balances, interest earned, and growth charts.Invest £1,500 Per Month — High-Earner Growth CalculatorSee how investing £1,500 monthly builds wealth over time. Projections for 10, 20, and 30-year horizons with compound interest.Invest £2,000 Per Month — Accelerated Wealth CalculatorCalculate how £2,000 monthly investments compound into serious wealth. See projections with charts, milestones, and breakdowns.

The power of monthly contributions

Regular monthly investing is one of the most effective wealth-building strategies available to ordinary people. By contributing a fixed amount each month, you benefit from pound-cost averaging — buying more shares when prices are low and fewer when prices are high. Over decades, even modest monthly contributions can compound into life-changing sums.

How much should I save each month?

A common guideline is the 50/30/20 rule: 50% of income for needs, 30% for wants, and 20% for saving and investing. If you earn £2,500/month after tax, that's £500/month towards investments. But even £100/month invested at 7% for 25 years grows to approximately £81,000 — with only £30,000 contributed. Use the calculator to find your sweet spot.

Monthly vs lump sum investing

While lump sum investing statistically outperforms over the long term (because markets tend to rise), monthly investing is more practical for most people and reduces the risk of investing a large sum at the worst possible time. The best approach is often to invest what you have now, then set up a monthly direct debit for ongoing contributions.

Monthly Compound InterestCalculator