How This Tool Works
📋 Purpose
Use this tool to plan how your investment might grow over time. It combines real UK inflation data, clear return assumptions, and compound-interest maths so you can compare outcomes in plain English.
⚙️ How It Works
- 1Choose Projection Mode to forecast growth, or Goal Mode to find the monthly amount needed for your target.
- 2Enter your starting amount, monthly contribution, time horizon, and risk level.
- 3The tool runs three estimated return scenarios and calculates future value using compound growth.
- 4It also shows inflation-adjusted real value so you can compare buying power, not just headline numbers.
- 5Review milestones and what-if comparisons, then adjust your plan as needed.
Ready to calculate
Update your inputs on the left, then click Calculate to view results.
• This planner uses real UK inflation data where available, plus clear assumptions and your own inputs, to give a practical estimate for planning (not personal financial advice).
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Simple Guide to Investment Planning
A plain-English guide to help you plan your investments step by step.
📅 Last updated: February 2026
Quick Tips
Jump-start your understanding with these essential tips
Time matters more than trying to pick the perfect return rate. Starting earlier gives your money longer to grow.
The inflation-adjusted figure shows what your money may really buy in future, not just the headline amount.
Choose a monthly amount you can keep paying. Consistency is better than setting a high number you cannot maintain.
Your income and costs change. Re-run the tool once or twice a year so your plan stays practical.
ISAs and pensions can help your money go further. Check GOV.UK rules for your situation before deciding.
Step-by-Step Guide
Follow these steps to get the most from this tool
Projection mode shows what your current plan might grow to.
Goal mode shows what monthly amount you may need for a target.
If you are unsure, start with Projection mode first.
Add your starting amount, monthly contribution, and time period.
Use numbers that match your real budget now, not your best-case plan.
Try a few options to see what feels affordable.
A longer time horizon usually gives your money more chance to recover from bad years.
Low risk is steadier but often grows slower. Higher risk can grow faster but can also drop more.
Pick a level you can stick with during market ups and downs.
The tool shows low, medium, and high return scenarios.
Use the range to plan safely, rather than relying on one single number.
If your goal only works in the high scenario, you may want to raise contributions or extend your timeline.
Test simple changes like +£50 per month, a longer time period, or lower returns.
This helps you see which change gives the biggest improvement in your final pot.
Update your plan each year as your household budget changes.
Advanced Topics
Deep dives for advanced users
ISAs and pensions can reduce tax on growth. Rules can change, so always check the latest GOV.UK guidance before acting.
Small regular investing over a long period often beats trying to catch up later with much larger payments.
This tool focuses on building your pot. For retirement withdrawal planning, use it as a starting point and get regulated advice if needed.
Paying in monthly can smooth market ups and downs. It also helps turn investing into a routine.
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Frequently Asked Questions
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