Lifestyle Creep Calculator

About this calculator

Lifestyle creep — sometimes called lifestyle inflation — is the slow, easy habit of spending more as you earn more, so a pay rise quietly disappears into bigger bills instead of bigger savings. This calculator compares your income and spending before and after a raise to show how much of that extra money you are actually keeping, and what the part absorbed by higher spending could be worth if you invested it instead. It is a way to picture the trade-off, not a judgement on how you spend.

How to read your results

Enter your take-home income and spending before and after the change. The headline figure is the long-run opportunity cost: what the spending you added could have grown to if you had invested it every month at your assumed return. The three stats break the raise down — the share you kept, the amount absorbed by extra spending each month, and the amount left over as savings each month. Adjust the return and years to see how the gap widens over time. Keeping even a slightly larger slice of each raise compounds into a meaningful difference.

Worked example

Your income rises from $4,000 to $5,000 a month (a $1,000 raise) while your spending goes from $3,000 to $3,600. You assume a 7% annual return over 20 years.

Of the $1,000 raise, $600 a month is absorbed by higher spending and $400 is kept — so you keep 40% of the raise. Invested monthly at 7% for 20 years, that absorbed $600 a month could grow to about $312,556 (from $144,000 of contributions). Keeping more of the raise instead would put much of that growth back in your pocket.

Frequently asked questions

What is lifestyle creep?

Lifestyle creep, or lifestyle inflation, is the tendency to raise your spending as your income grows — upgrading the car, the apartment, the subscriptions — so a raise leaves your savings roughly where they were. It is not inherently bad; some of a raise rewarding yourself is reasonable. The risk is letting it absorb the whole increase by default, which quietly delays bigger goals.

How much of a raise should I keep?

There is no universal number, which is why this tool lets you model any split. A common rule of thumb is to bank a large share of each raise — for example keeping half or more — and let yourself enjoy the rest. The preset chips make it easy to see what your spending would need to be to keep 25%, 50%, or 100% of the raise, so you can pick a target that fits your goals.

Why does the absorbed amount look so large after 20 years?

Because it is compounded. A modest monthly amount invested steadily for decades grows far beyond the sum of the contributions thanks to returns on returns. The headline figure shows that compounding effect, which is exactly why redirecting even part of a raise to investing can matter so much over a long horizon. It assumes a constant return for illustration; actual markets fluctuate.

Is this financial advice?

No. This is a planning estimate based on the numbers you enter and a fixed-return assumption you choose. Your right balance between spending and saving depends on your goals, debts, and circumstances. Treat the result as a way to visualise the trade-off and start a plan, not as a recommendation to invest in any particular way.

How it's calculated

Raise = new income − old income, floored at zero. Spending increase = new spending − old spending, floored at zero. Absorbed = the smaller of the spending increase and the raise (this model never counts more than the raise itself as creep). Saved from raise = raise − absorbed; kept % = saved ÷ raise × 100 (zero when there is no raise). The future value uses the ordinary-annuity formula: with a monthly rate r = annual return ÷ 12 and n = years × 12 months, future value = absorbed × ((1 + r)ⁿ − 1) ÷ r; when the return is zero it is simply absorbed × n. Everything is arithmetic on the figures you enter — it is a planning aid, not financial advice, and real investment returns vary year to year.