Set a target amount and find out how long it will take to reach it — or how much you need to save each month. A reverse compound interest calculator for goal-oriented savers.
A standard compound interest calculator tells you: "If I invest £X per month for Y years at Z% return, how much will I have?" A savings goal calculator does the opposite. It asks: "I want to reach £X — how much do I need to save each month, or how long will it take?"
This reverse calculation is incredibly useful for practical financial planning. Instead of guessing at monthly amounts and checking whether they are enough, you start with the end goal and work backwards to a concrete action plan. It turns an abstract ambition into a specific monthly savings target.
Our compound interest calculator includes a Goal Mode that performs exactly this reverse calculation. Enter your target amount, expected return rate, and time horizon, and it will tell you the required monthly contribution. Or fix the monthly amount and it will calculate the time needed.
| Goal | Target | Typical timeline | ~Monthly needed |
|---|---|---|---|
| Emergency fund | £5,000-£10,000 | 6-12 months | £400-£850 |
| House deposit | £25,000-£40,000 | 3-5 years | £400-£700 |
| £100k milestone | £100,000 | 10-15 years | £350-£550 |
| Half a million | £500,000 | 20-25 years | £700-£1,100 |
| Retirement pot | £750,000+ | 25-35 years | £500-£900 |
Monthly amounts assume cash savings at 4% for short-term goals and investment returns of 7% for goals 5+ years away. Amounts are approximate — use the calculator for your exact scenario. Starting from £0 with no lump sum.
The difference between cash savings and investing widens dramatically over longer time horizons. For a short-term emergency fund, a high-interest savings account is perfect. But for goals five or more years away, investing in a Stocks & Shares ISA typically gets you there significantly faster.
| Goal amount | Cash (4%) | Investing (7%) | Time saved |
|---|---|---|---|
| £50,000 | ~12.5 years | ~10.5 years | ~2 years |
| £100,000 | ~20 years | ~15 years | ~5 years |
| £250,000 | ~33 years | ~22 years | ~11 years |
| £500,000 | ~47 years | ~28 years | ~19 years |
Based on £300/month contributions, starting from £0. Investment returns are not guaranteed and capital is at risk. Cash savings assume a constant 4% rate, which may vary over time.
Trying to save for a house deposit, emergency fund, and retirement simultaneously can feel overwhelming. Prioritise: build your emergency fund first (3-6 months of expenses), then focus on your next major goal. Your workplace pension handles retirement savings in the background through auto-enrolment.
A £100,000 goal sounds daunting. But £500/month invested at 7% reaches £100,000 in about 11 years. Framing it as a monthly target — one you can automate and forget about — makes it manageable. The calculator converts overwhelming long-term goals into bite-sized monthly actions.
Short-term (under 3 years): cash savings account or Cash ISA. Medium-term (3-5 years): mix of cash and cautious investments. Long-term (5+ years): Stocks and Shares ISA. For house deposits under £450,000, a Lifetime ISA gives a 25% government bonus on up to £4,000/year.
Check your progress every three months. If you are ahead of schedule, you can either reach the goal sooner or reduce your monthly contribution slightly. If you are behind, consider whether you can increase contributions or extend your timeline. Flexibility prevents discouragement.
Our compound interest calculator includes a dedicated Goal Mode that makes reverse calculations easy. Instead of entering a monthly contribution and seeing the result, you enter your target amount and the calculator tells you exactly how much to invest per month, or how many years it will take at your current savings rate.
You can experiment with different scenarios: What if I save an extra £100/month? What if I expect 8% returns instead of 6%? What if I extend my timeline by 2 years? This helps you find the most realistic and comfortable path to your goal based on your actual financial situation.
Try Goal Mode and see what it takes to reach your savings target.
Open compound interest calculatorOpen a free Stocks & Shares ISA and start investing towards your savings goal from just £1. Zero commission, no platform fees, and FCA regulated.
Capital at risk. This is not financial advice. Affiliate link — we may earn a commission at no extra cost to you.
We value your privacy
We use cookies for analytics (Google Analytics) to understand how visitors use this site. No personal data is shared with advertisers. Read our Cookie Policy and Privacy Policy.