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, and 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.

CompoundWise

Turn £300/month into £245,884

Free UK calculator · No signup · Based on ISA investing

By CompoundWise Team·Updated April 2026

Starting amount

£0£20k£200k

Monthly contribution

£0£1k£5k

Expected annual return

Time horizon

yrs

Invest £300/month for 25 years at 7%

£153,022

earned in interest alone

That's more than you put in, your money earns money

Total value

£243,022

You put in

£90,000

Your money63% from compounding

To reach £243,022, most UK investors use a Stocks & Shares ISA

Most UK beginners start here

Open a free Stocks & Shares ISA

Trading 212 · No fees · Start from £1 · FCA regulated

Start your £300/month plan →

Open an account in 5 minutes · No minimum deposit

Capital at risk · Affiliate link · Not financial advice

Compare other platforms ↓

Keeping this in a savings account? You'd have ~£88,846 less

Compared to investing at 7% vs a 4% cash savings account

Growth Over Time

Recommended for your plan

Affiliate

Trading 212

Popular

No commission · Start from £1 · FCA regulated

No commission on stocks1M+ UK usersFree ISA included

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

Start with Trading 212 →

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

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 →

Best for beginnersAffiliate

Trading 212

Start from £1 · No commission · Popular with UK investors

Open free account →

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.

By the CompoundWise Team · Updated April 2026

UK-based financial education · Not financial advice

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.

Frequently asked questions

Get weekly investing tips & calculator updates

Free, no spam. Unsubscribe anytime.