See the true long-term cost of spending versus saving. Enter any amount to see what it compounds to by retirement — and whether the purchase is genuinely worth its future value.
| Year | Value if Invested | Gain |
|---|
Every pound spent instead of invested has a compound opportunity cost. A £500 purchase at 35 foregoes approximately £2,700 at retirement (7% return, 25 years). A £100/month habit foregoes approximately £95,000. This does not mean every purchase is wrong — it means understanding the true long-term cost of spending choices leads to more deliberate decisions about what is genuinely worth the opportunity cost.
| Spending Habit | Monthly Cost | Future Value (7%, 25 yrs) | Is It Worth It? |
|---|---|---|---|
| Daily takeaway coffee | £60/mo | £57,000 | Possibly not |
| Gym membership (unused) | £40/mo | £38,000 | Definitely not |
| Streaming subscriptions (all) | £50/mo | £47,500 | For some, yes |
| Weekend restaurant dining | £200/mo | £190,000 | Personal call |
| New car (vs second-hand) | £300/mo extra | £285,000 | Rarely |
Opportunity cost is what you give up when you choose one option over another. In personal finance: when you spend £500, you give up not just £500 but all future compound growth on that £500. At 7% annual return over 25 years, £500 becomes approximately £2,700. The true cost of the £500 purchase is £2,700 in future value foregone. This does not mean spending is wrong — it means making spending decisions with full awareness of their true long-term cost.