Calculators Hub
Explore tools to plan and compare
A growing collection of quick, no-login calculators to help you weigh up mortgage overpayments, investing, budgeting, and long-term planning. All run in your browser.
Compound interest
Compound interest calculator
See how your money could grow with compounding, regular deposits, or withdrawals.
Example presets
Use a quick example if you want to see how saving, compounding, or drawdown changes the result.
Compound interest made simple
Enter a starting amount, time, expected return, and any regular deposits or withdrawals. We'll show a simple estimate of how the balance could change over time.
Compounding frequency
Deposit timing
Regular contributions
Advanced
Different frequencies are approximated to match the monthly compounding timeline.
Future value
£6,417
Total interest earned
£1,417
Total deposits
£0
Total withdrawals: £0
Effective yearly rate
5.12%
Portfolio growth vs contributions
This shows how much of the final balance comes from your own money and how much comes from investment growth over time.
Year 5
How to read the summary
Initial deposit
£5,000
Interest rate
5% per year
Compounding
monthly
Time
5 years 0 months
Regular contributions
None
These are estimates. Real investing returns can change over time.
Breakdown
| Period | Deposits | Withdrawals | Interest | Balance |
|---|---|---|---|---|
| Month 1 | £0 | £0 | £21 | £5,021 |
| Month 2 | £0 | £0 | £21 | £5,042 |
| Month 3 | £0 | £0 | £21 | £5,063 |
| Month 4 | £0 | £0 | £21 | £5,084 |
| Month 5 | £0 | £0 | £21 | £5,105 |
| Month 6 | £0 | £0 | £21 | £5,126 |
| Month 7 | £0 | £0 | £21 | £5,148 |
| Month 8 | £0 | £0 | £21 | £5,169 |
| Month 9 | £0 | £0 | £22 | £5,191 |
| Month 10 | £0 | £0 | £22 | £5,212 |
| Month 11 | £0 | £0 | £22 | £5,234 |
| Month 12 | £0 | £0 | £22 | £5,256 |
| Month 13 | £0 | £0 | £22 | £5,278 |
| Month 14 | £0 | £0 | £22 | £5,300 |
| Month 15 | £0 | £0 | £22 | £5,322 |
| Month 16 | £0 | £0 | £22 | £5,344 |
| Month 17 | £0 | £0 | £22 | £5,366 |
| Month 18 | £0 | £0 | £22 | £5,389 |
| Month 19 | £0 | £0 | £22 | £5,411 |
| Month 20 | £0 | £0 | £23 | £5,434 |
| Month 21 | £0 | £0 | £23 | £5,456 |
| Month 22 | £0 | £0 | £23 | £5,479 |
| Month 23 | £0 | £0 | £23 | £5,502 |
| Month 24 | £0 | £0 | £23 | £5,525 |
| Month 25 | £0 | £0 | £23 | £5,548 |
| Month 26 | £0 | £0 | £23 | £5,571 |
| Month 27 | £0 | £0 | £23 | £5,594 |
| Month 28 | £0 | £0 | £23 | £5,617 |
| Month 29 | £0 | £0 | £23 | £5,641 |
| Month 30 | £0 | £0 | £24 | £5,664 |
| Month 31 | £0 | £0 | £24 | £5,688 |
| Month 32 | £0 | £0 | £24 | £5,712 |
| Month 33 | £0 | £0 | £24 | £5,735 |
| Month 34 | £0 | £0 | £24 | £5,759 |
| Month 35 | £0 | £0 | £24 | £5,783 |
| Month 36 | £0 | £0 | £24 | £5,807 |
| Month 37 | £0 | £0 | £24 | £5,832 |
| Month 38 | £0 | £0 | £24 | £5,856 |
| Month 39 | £0 | £0 | £24 | £5,880 |
| Month 40 | £0 | £0 | £25 | £5,905 |
| Month 41 | £0 | £0 | £25 | £5,929 |
| Month 42 | £0 | £0 | £25 | £5,954 |
| Month 43 | £0 | £0 | £25 | £5,979 |
| Month 44 | £0 | £0 | £25 | £6,004 |
| Month 45 | £0 | £0 | £25 | £6,029 |
| Month 46 | £0 | £0 | £25 | £6,054 |
| Month 47 | £0 | £0 | £25 | £6,079 |
| Month 48 | £0 | £0 | £25 | £6,104 |
| Month 49 | £0 | £0 | £25 | £6,130 |
| Month 50 | £0 | £0 | £26 | £6,155 |
| Month 51 | £0 | £0 | £26 | £6,181 |
| Month 52 | £0 | £0 | £26 | £6,207 |
| Month 53 | £0 | £0 | £26 | £6,233 |
| Month 54 | £0 | £0 | £26 | £6,259 |
| Month 55 | £0 | £0 | £26 | £6,285 |
| Month 56 | £0 | £0 | £26 | £6,311 |
| Month 57 | £0 | £0 | £26 | £6,337 |
| Month 58 | £0 | £0 | £26 | £6,364 |
| Month 59 | £0 | £0 | £27 | £6,390 |
| Month 60 | £0 | £0 | £27 | £6,417 |
Example scenario
Example scenario
This example shows how compound growth can build when you start with a lump sum and keep adding regularly.
- Starting amount: £5,000
- Monthly contribution: £200
- Annual growth rate: 5%
- Time invested: 15 years
You can use this kind of example to see how much of the final balance comes from your own deposits and how much comes from growth building on earlier growth.
Learn the basics
How the Compound Interest Works
Compounding, contribution timing, and long-term growth
Compound interest means growth can build on earlier growth. Once returns are added to the balance, future returns are calculated on a larger amount, which is why time matters so much.
Regular deposits often matter more than people expect. Even if returns are modest, steady monthly contributions can keep pushing the balance higher and give each deposit its own time to grow.
This tool is most useful for building intuition rather than predicting exact results. Real investing returns move up and down, but the calculator helps show how time, rate assumptions, and contribution habits interact.
Pros vs cons
Pros
- Makes long-term saving and investing easier to visualise.
- Shows the difference between your own contributions and investment growth.
- Useful for ISA, pension, and general investing planning.
Cons
- Future returns will not arrive in a smooth straight line in real life.
- Does not automatically include platform fees, tax, or inflation.
- Short-term results can differ a lot from long-term averages.
Glossary
- Compounding
- Growth being added to your balance so future growth is earned on both your original money and earlier gains.
- Contribution
- Money you add to the balance over time, such as a monthly investment or savings deposit.
Frequently asked questions
Is compound growth guaranteed?+
No. This is a projection based on the return you enter. Real savings rates and market returns can change.
Why do small monthly deposits add up so much?+
Because each deposit has time to earn growth, and later growth then builds on that earlier growth too.
Does compounding frequency make a huge difference?+
Usually not at everyday rates, but more frequent compounding can still lift the final value slightly.
Related calculators
Try the next step after Compound Interest
These tools answer nearby questions, so you can compare the next trade-off without starting from scratch.
Fees
Fee Drag: Investment Costs
See how investment fees can quietly reduce your long-term returns.
Open calculatorRetirement
ISA vs SIPP Monthly
Compare ISA and pension investing to see which may suit your goal better.
Open calculatorPlanning
Net Worth Tracker
Add up what you own and owe to get a clearer picture of your financial position.
Open calculatorThese calculators are for educational purposes only and do not constitute financial advice.
They use simplified assumptions and browser-based estimates. Read the full disclaimer before making important decisions.