Savings vs. Investment Calculator
Enter an amount and one annual rate — used for both inflation and investment return — and compare, side by side over 20 years, what that amount would be worth if you just saved it versus if you invested it.
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Saving vs. investing the same amount, over 20 years
| Year | Value if saved (adjusted for inflation) | Value if invested (future money, not adjusted for inflation) |
|---|---|---|
| 1 | £9,523.81 | £10,500.00 |
| 2 | £9,070.29 | £11,025.00 |
| 3 | £8,638.38 | £11,576.25 |
| 4 | £8,227.02 | £12,155.06 |
| 5 | £7,835.26 | £12,762.82 |
| 6 | £7,462.15 | £13,400.96 |
| 7 | £7,106.81 | £14,071.00 |
| 8 | £6,768.39 | £14,774.55 |
| 9 | £6,446.09 | £15,513.28 |
| 10 | £6,139.13 | £16,288.95 |
| 11 | £5,846.79 | £17,103.39 |
| 12 | £5,568.37 | £17,958.56 |
| 13 | £5,303.21 | £18,856.49 |
| 14 | £5,050.68 | £19,799.32 |
| 15 | £4,810.17 | £20,789.28 |
| 16 | £4,581.12 | £21,828.75 |
| 17 | £4,362.97 | £22,920.18 |
| 18 | £4,155.21 | £24,066.19 |
| 19 | £3,957.34 | £25,269.50 |
| 20 | £3,768.89 | £26,532.98 |
How it's worked out
Both columns use the exact same rate, applied in opposite directions, once a year:
Value if saved = Amount ÷ (1 + rate ÷ 100)ⁿ — the same formula our inflation calculator uses; inflation erodes what your money can buy.
Value if invested = Amount × (1 + rate ÷ 100)ⁿ — the same formula our investment calculator uses; a return compounds your money.
Using one rate for both sides isn't a claim that inflation and investment returns are usually equal — it's a way to isolate a single question: how much difference does it make whether that percentage works against your money (as inflation on idle cash) or for it (as a return on an investment)?
Worked example
Suppose you have £10,000 and use 5% for both rates. If just saved, it would be worth about £7,835.26 in today's terms after 5 years, £6,139.13 after 10 years, and £3,768.89 after 20 years. If invested instead, at the same 5%, it would grow to about £12,762.82 after 5 years, £16,288.95 after 10 years, and £26,532.98 after 20 years.
Careful when comparing the two columns: the first is in today's money, the second in future money. In today's money, an investment that grows exactly as fast as prices only keeps its value — it still buys what £10,000 buys today — while the saved cash buys only what £3,768.89 buys today. So the real difference after 20 years is about £6,231.11 of today's purchasing power; the £26,532.98 is what you would see on the statement, not what it can buy.
Frequently asked questions
Why does the tool use the same percentage for both inflation and investment return?
This is a comparison, not a forecast: using one rate for both sides isolates the effect of doing something with your money (investing it) versus leaving it as cash (where inflation alone erodes it), so the size of the gap is easy to see. Real inflation and real investment returns are rarely exactly equal, and both change from year to year.
Does "value if saved" mean my bank balance actually goes down?
No — same as our inflation calculator: the number in a bank account doesn't fall by itself. What falls is what that number can buy, which is what this column shows.
Does "value if invested" account for tax, fees, or risk?
No — this is a pure mathematical projection at the rate you enter. Real investments involve risk, and real returns are reduced by tax and fees; use this as a comparison tool, not a guarantee.
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