How much should I invest each month?

Start with the goal, not the amount

Before asking how much to invest, ask what you are investing for. A vague intention to "build wealth" is harder to plan around than a specific goal: a retirement pot, a house deposit supplement, financial independence by a certain age, or an inheritance for your children.

The goal gives you two critical inputs: a target amount and a timeframe. With those two things, you can work backwards to a monthly figure.

Working backwards: a worked example

Suppose you want to build a £150,000 pot in 15 years. You currently have £8,000 invested. Assuming 6% average annual growth:

• Your £8,000 already invested would grow to around £19,000 over 15 years without adding anything more
• You therefore need to build roughly £131,000 through monthly contributions
• At 6% annual growth, this requires approximately £460 per month

Use the monthly contribution calculator to run your own numbers with different targets, timelines, and starting points.

What if the number feels too high?

There are three variables to adjust: the target, the timeline, and the assumed return. Extending your timeline by five years can dramatically reduce the required monthly amount. Adjusting the target to something you actually need rather than a round number can also help.

If the monthly figure required is genuinely unaffordable, it is better to start smaller and adjust expectations than to overcommit and stop entirely. A smaller consistent contribution over a long period outperforms an ambitious contribution that gets abandoned.

The sustainability principle

The right monthly contribution is the largest amount you can invest without touching it. This means:

• You have an emergency fund (typically 3–6 months of essential expenses) held separately in cash before investing
• Your contribution does not create cash flow stress in a normal month
• You could maintain it through a period of market falls without being tempted to stop

Many investors find that starting at a conservative level and gradually increasing contributions as income grows works better than starting high and feeling pressure to reduce.

Lump sums and irregular income

If you receive irregular income — bonuses, freelance payments, inheritance — lump sum investing at those moments can supplement your regular monthly contributions significantly. Evidence generally favours investing lump sums promptly rather than spreading them over time, though for very large sums some people find gradual investing easier to commit to emotionally.

Use the lump sum vs monthly calculator to compare how different approaches affect your outcome.