Use this when…
- You want to know how much £100 or £200 saved each month could become.
- You are comparing saving for ten years versus twenty years.
- You want to understand inflation and fees before comparing products.
UK · SAVINGS & INVESTING
How could your savings grow with compound interest?
Explore a pounds-based savings and investing plan using your own assumed return. Compare what you put in with growth, fees, purchasing power and a target balance.
NEW TO THIS CALCULATOR?
UK compound saving: work out a future balance before committing money
Saving for a home, emergency fund or long-term goal? This calculator can show a hypothetical future savings pot with monthly deposits. You choose the interest or investment-return assumption rather than relying on an invented live bank rate.
Start with these numbers
- 1. Enter money already saved, planned monthly saving and the number of years.
- 2. Enter an effective yearly rate as a hypothetical scenario. Try 0% for deposits only.
- 3. Use optional fee, deposit increase and inflation fields if you understand them; otherwise begin with zero fees and no step-up.
What the result means
The future pot is the model's nominal balance, and 'total saved' is your own deposits. Their difference is only theoretical growth. The today's-money figure accounts for inflation and is not a bank account statement.
Try this example
Try £5,000 at the start, £200 a month over 15 years. Compare 0% and 4% growth, then raise the monthly amount and note how your deposits—not just interest—affect the pot.
Watch out for this mistake AER is an annual equivalent rate for savings products; this model treats your entry as an effective annual assumption. Do not assume the whole return is guaranteed or tax-free.
More detailed explanations appear below the calculator ↓
Your savings plan
The result is not a savings-account offer, forecast interest rate, pension guarantee or recommendation. AER/APR definitions, account tax treatment, fees, ISA limits, investment volatility and early withdrawals may change real results.
Estimated future savings
Future savings pot (illustration)£106,723.40Target met under your assumptions
Estimated growth of your savings
Total amount saved£53,000.00
Estimated gain or loss£53,723.40
Today's-money equivalent£71,821.79
Monthly amount needed for your target£185.17
Assumed annual return after fees6%
Try different return assumptions
Lower scenario (4%)£83,723.96
Chosen return (6%)£106,723.40
Higher scenario (8%)£137,104.60
Year-by-year projection
| Year | Paid in | Future value |
|---|---|---|
| 0 | £5,000.00 | £5,000.00 |
| 1 | £7,400.00 | £7,765.31 |
| 5 | £17,000.00 | £20,588.29 |
| 10 | £29,000.00 | £41,448.93 |
| 15 | £41,000.00 | £69,365.17 |
| 20 | £53,000.00 | £106,723.40 |
FINANCIAL EDUCATION
How to calculate interest on UK savings
- 01
Add the opening balance and what you can put aside every month. If you only want a lump-sum example, set monthly saving to zero.
- 02
Choose the number of years and input an effective annual interest or investment-growth assumption. A quoted AER is different from an APR calculated with other compounding rules.
- 03
Include a possible annual platform or fund fee, changes in monthly saving and an inflation assumption if useful. The projection applies fees as a recurring percentage of assets, not a fixed account charge.
- 04
Review projected growth in future pounds and the present-day buying-power equivalent. Check ISA and pension tax treatment separately if using a tax-advantaged account.
Example: £5,000 at the start plus £200 a month for 15 years. Try a 0% return and then a higher hypothetical effective return to separate your deposits from possible growth.
Limits of this example
The result is not a savings-account offer, forecast interest rate, pension guarantee or recommendation. AER/APR definitions, account tax treatment, fees, ISA limits, investment volatility and early withdrawals may change real results.
Common questions
Is the input rate the same as AER?
It is treated as an effective annual rate. This makes comparison with AER-style savings assumptions reasonable, but it is not a bank's actual rate or contract.
Can I use it for a Stocks and Shares ISA?
Only as a scenario. It does not enforce the ISA subscription allowance or calculate investment tax rules.
Does it calculate my workplace pension?
This is a general compound saving model. For employer pension contributions and your existing pension pot, use the separate UK pension calculator.
What does ‘today's money’ mean?
The future figure is divided by cumulative assumed inflation, indicating purchasing power if inflation follows your input.
How we calculate growth
Your assumed effective annual rate is converted into a monthly growth factor. Regular contributions enter at the beginning or end of each month and may rise each year. The estimate is not a quoted AER or a promise of future savings interest.
Try different return assumptions
IN-DEPTH CALCULATOR GUIDE
UK compound saving: work out a future balance before committing money
Saving for a home, emergency fund or long-term goal? This calculator can show a hypothetical future savings pot with monthly deposits. You choose the interest or investment-return assumption rather than relying on an invented live bank rate.
01
What can a savings growth estimate help you decide?
A couple might use this tool when planning a property deposit; another household may be setting aside money for a child or future major expense. It shows how amount, time and a hypothetical rate combine—not which UK savings account to buy.
The example can be used for ordinary saving or investments, but those products have very different risks. Cash savings may have changing interest rates while investments may fall in value. Do not assume one smooth rate is realistic for either product.
02
The three basic fields to complete first
Opening savings is the money you already have. Monthly saving is the amount you can add on a repeatable basis. Years is how long you expect to keep saving. If you only need to see deposits, enter 0% in the growth field.
For instance, a £5,000 opening balance and £200 monthly over 15 years would result in £41,000 of contributions before any assumed growth: £5,000 plus 180 deposits of £200. Try another rate to see the mathematical difference.
03
Understanding the chart and purchasing power
The projected future value is not the same as the contributions line. With positive assumed growth, the gap is hypothetical interest or investment growth after any modelled asset fees. With a negative return, the portfolio can end below the amount paid in.
The purchasing-power value is smaller when you assume inflation because future pounds may buy less. That is a helpful planning lens for long-term goals, but not a forecast of actual inflation or the price of a specific property.
04
Comparing a real UK savings product
When you compare offers, confirm AER, fixed versus variable interest, deposit limits, withdrawal restrictions and any tax treatment outside this calculator. An investment can have trading costs and risk that a bank account does not.
The 'monthly amount to target' is only what the algebra requires under exactly the assumptions you entered. Check your budget before planning to save that amount and compare optimistic and cautious cases.
Educational planning only. Verify relevant official records and lender or tax documents before making decisions.