Savings example
What Would £100 a Month Become Over 10 Years at 5%?
A plain-English savings example showing what £100 a month could become over 10 years at 5%, with comparisons for different amounts, rates, and timeframes.
Saving £100 a month can sound modest, but the habit becomes more interesting when the money has time to grow. If you saved £100 at the end of every month for 10 years and it grew at 5% a year with monthly compounding, you would end up with about £15,528.
You would have paid in £12,000 yourself. The remaining £3,528 is the estimated growth from compounding, before tax, fees, inflation, or changes in the rate. Use the compound interest calculator to run the same example with your own monthly amount, rate, and timeline.
The short version
For this example:
- Monthly deposit: 100
- Time: 10 years
- Total paid in: £12,000
- Annual rate: 5%
- Compounding: monthly
- Deposit timing: end of each month
- Estimated final balance: about £15,528
- Estimated growth: about £3,528
In plain English: you save £100 every month, growth is added to the balance, and future growth is earned on both your deposits and earlier growth.
Try it with your own numbers
Open the compound interest calculator, set the starting amount to £0, choose a 5% annual rate, set the term to 10 years, and add a £100 monthly deposit.
If you are saving toward a specific target, the savings goal calculator can work the other way around: enter the goal and timeline to estimate the monthly saving needed.
How the calculation works
The calculator treats each month as a small step. You do not need to know the formula to understand the idea:
- Add any interest for the month.
- Add the monthly deposit.
- Carry the new balance into the next month.
- Repeat for 120 months.
The first £100 deposit has almost the full 10 years to grow. The final £100 deposit has almost no time to grow. That is why regular-saving calculations are a little different from a single lump sum.
The main example
Here is the headline example, rounded to the nearest pound:
| Monthly saving | Annual rate | Time | Paid in | Estimated final balance | Estimated growth |
|---|---|---|---|---|---|
| £100 | 5% | 10 years | £12,000 | £15,528 | £3,528 |
The important thing is not only the final balance. It is the split between money you contributed and growth from compounding.
In this example, roughly 77% of the final balance comes from your own deposits and roughly 23% comes from growth. That is a useful way to read the result: the calculator is not saying you found a magic shortcut, but it is showing what a steady habit plus time could do.
If you save more or less each month
Keeping the same 5% annual rate and 10-year term, the final estimate changes like this:
| Monthly saving | Paid in over 10 years | Estimated final balance | Estimated growth |
|---|---|---|---|
| £25 | £3,000 | £3,882 | £882 |
| £50 | £6,000 | £7,764 | £1,764 |
| £100 | £12,000 | £15,528 | £3,528 |
| £250 | £30,000 | £38,821 | £8,821 |
| £500 | £60,000 | £77,641 | £17,641 |
The pattern is simple: if all assumptions stay the same, doubling the monthly saving roughly doubles the result.
If the rate is different
The rate matters because it is applied again and again. Here is £100 a month for 10 years at a few different annual rates:
| Annual rate | Paid in | Estimated final balance | Estimated growth |
|---|---|---|---|
| 0% | £12,000 | £12,000 | £0 |
| 1% | £12,000 | £12,615 | £615 |
| 3% | £12,000 | £13,974 | £1,974 |
| 5% | £12,000 | £15,528 | £3,528 |
| 7% | £12,000 | £17,308 | £5,308 |
| 10% | £12,000 | £20,485 | £8,485 |
A higher assumed rate makes a big difference, but it also deserves more caution. Savings rates, investment returns, tax rules, and fees can all change. A calculator can show a scenario, not guarantee an outcome.
If you give it more time
Time is the other big lever. Here is £100 a month at 5%, but with different timelines:
| Time | Paid in | Estimated final balance | Estimated growth |
|---|---|---|---|
| 5 years | £6,000 | £6,801 | £801 |
| 10 years | £12,000 | £15,528 | £3,528 |
| 15 years | £18,000 | £26,729 | £8,729 |
| 20 years | £24,000 | £41,103 | £17,103 |
| 30 years | £36,000 | £83,226 | £47,226 |
This is why compound growth often looks slow at first and more powerful later. In the 5-year example, most of the balance is your own deposits. By 30 years, the estimated growth is larger than the total amount paid in.
A few everyday ways to use the result
The £15,528 estimate becomes more useful when you compare it with a real-life goal:
| Goal | How the £100 a month example compares |
|---|---|
| Build a £5,000 emergency fund | The monthly habit would pass this level before the 10-year point, assuming the deposits continue. |
| Save for a £10,000 car deposit | The example has enough room for the target, but the timing still matters if the money is needed earlier. |
| Aim for £20,000 in 10 years | £100 a month at 5% would fall short, so you would need a higher monthly deposit, a longer timeline, or a different rate assumption. |
| Start a long-term investment habit | The example shows the power of consistency, but investment values can rise and fall along the way. |
This is where the savings goal calculator is useful. Instead of asking "what will my monthly saving become?", it helps you ask "what do I need to save each month to reach a target?"
What if deposits are made at the start of each month?
Timing makes a small difference. If the £100 deposit is made at the beginning of each month instead of the end, the 10-year estimate at 5% rises from about £15,528 to about £15,593.
That is only about £65 more in this example, but it shows the principle: money that arrives earlier has more time to earn.
Run the example in the calculator
To recreate the main estimate in the compound interest calculator, use:
- Starting balance: £0
- Monthly deposit: £100
- Annual rate: 5%
- Time: 10 years
- Compounding: monthly
Then change one input at a time. Try £50 instead of £100, 3% instead of 5%, or 20 years instead of 10. That makes it easier to see which lever changes the result most.
Watch-outs
- A steady 5% rate is an assumption, not a promise.
- Investment returns can go down as well as up.
- Inflation can reduce what the future balance buys.
- Fees and tax can reduce the final amount.
- Monthly deposit timing can change the estimate slightly.
- If the rate is an APR, APY, or investment return, make sure you choose the calculator setting that matches it.
How to read the result
The £15,528 estimate is useful because it turns a monthly habit into a long-term number. It does not say whether £100 a month is enough for your goal.
If your goal is £20,000 in 10 years, this scenario falls short. If your goal is to build a first emergency fund or a medium-term savings pot, the same result might be encouraging. The number only becomes useful when you compare it with a real goal.
Tools mentioned in this article
- Compound interest calculator
- Savings goal calculator
- Daily compound interest calculator
- Investment return calculator
- CAGR calculator
Reader questions
Is 5% a savings rate or an investment return?
It can be either as a scenario, but the meaning changes. A savings rate is usually more predictable for a fixed account term. An investment return is uncertain and can vary from year to year.
Is £100 a month enough to make a difference?
It can be. The example shows that £100 a month is £12,000 of your own money over 10 years, plus possible growth. Whether it is enough depends on the goal you are comparing it with.
Should I use beginning-of-month or end-of-month deposits?
Use the setting that matches how you actually save. If you transfer money just after payday, beginning-of-month timing may be closer. If you save at the end of the month, end-of-month timing is closer.
What happens if I miss a few months?
Missing deposits lowers the final estimate because less money goes in and some deposits lose time to grow. You can model this by reducing the monthly amount slightly or by using a shorter effective saving period.
Is this financial advice?
No. This is an educational calculator example using simplified assumptions. It is not personal financial, tax, or investment advice.
