Purchase Impact Calculator
A price tag only tells you what a purchase costs today. This calculator shows what it costs your future self: the amount that money would grow to if you invested it instead, how many days of work it takes to earn it, and — if you share your savings plan — how many days it pushes back your financial independence date. Enter the price and an expected real return to see the opportunity cost; add your net income and FIRE plan for the full picture. It is a way to make trade-offs visible, not a verdict on any purchase, and it is informational, not financial advice.
Tell us more for the full picture (optional)
Monthly savings + FIRE number unlock the financial-independence delay. All amounts in today's dollars.
If invested instead, worth in 30 years
$7,612.26
7.61× the price, at 7.00% real return in today's dollars
The price, invested and left alone
Year-by-year value
| Year | Invested value |
|---|---|
| 0 | $1,000.00 |
| 1 | $1,070.00 |
| 2 | $1,144.90 |
| 3 | $1,225.04 |
| 4 | $1,310.80 |
| 5 | $1,402.55 |
| 6 | $1,500.73 |
| 7 | $1,605.78 |
| 8 | $1,718.19 |
| 9 | $1,838.46 |
| 10 | $1,967.15 |
| 11 | $2,104.85 |
| 12 | $2,252.19 |
| 13 | $2,409.85 |
| 14 | $2,578.53 |
| 15 | $2,759.03 |
| 16 | $2,952.16 |
| 17 | $3,158.82 |
| 18 | $3,379.93 |
| 19 | $3,616.53 |
| 20 | $3,869.68 |
| 21 | $4,140.56 |
| 22 | $4,430.40 |
| 23 | $4,740.53 |
| 24 | $5,072.37 |
| 25 | $5,427.43 |
| 26 | $5,807.35 |
| 27 | $6,213.87 |
| 28 | $6,648.84 |
| 29 | $7,114.26 |
| 30 | $7,612.26 |
Compare scenarios
Run the same calculation with two or three input sets side by side. Differences are highlighted; every number comes from the same tested formula as the calculator above.
| Input | Scenario A | Scenario B |
|---|---|---|
| Price | ||
| Expected Real Return Pct | ||
| Years Horizon | ||
| Annual Net Income | ||
| Monthly Savings | ||
| Current Savings | ||
| Fire Number |
How it works
The invested alternative is plain compound interest: futureValue = price × (1 + r)^years, where r is your expected real (inflation-adjusted) annual return. Using a real return keeps the answer in today's purchasing power, so a $1,000 purchase at 7% real over 30 years shows up as roughly $7,612 of today's dollars — a 7.6× growth multiple. The year-by-year curve makes the compounding visible: most of the growth arrives in the later years, which is why long horizons make small prices look surprisingly large.
Days of work translates the price into time: workDays = price ÷ (annualNetIncome ÷ 260), using the common 260-working-days-per-year convention (52 weeks × 5 days, ignoring holidays and PTO for simplicity). Net income — what actually lands in your account — is the honest denominator, because you pay for purchases with after-tax money. Someone netting $52,000 a year earns $200 per working day, so a $1,000 purchase costs five full days at a desk.
The FIRE delay compares two runs of the same savings plan: one starting from your current savings, one starting from current savings minus the price (the purchase comes out of invested money). Each run solves for the years n to reach your FIRE number F from starting balance S with annual contributions C = 12 × monthlySavings at return r, using the end-of-year convention: n = ln((F·r + C)/(S·r + C)) ÷ ln(1 + r), or n = (F − S)/C when r = 0. The delay is the difference between the two, in days. If the purchase is larger than your current savings the start balance goes negative; the formula still holds unless the growth drag exceeds your contributions, in which case the reduced plan never converges and the calculator says so instead of showing a number.
Frequently asked questions
Is this just the 'latte factor'? Isn't that idea discredited?+
It is the latte-factor arithmetic, made verifiable — and the criticism of the concept is fair, so this tool doesn't hide from it. Critics rightly point out that small discretionary purchases are rarely the main driver of financial stress; housing, transport, healthcare, childcare, and income matter far more, and no amount of skipped coffees fixes a structural budget gap. The compounding math itself is not wrong, though: money spent genuinely cannot grow, and this calculator shows exactly how much growth a given price forgoes under your own assumptions. Use it to compare trade-offs you actually face — especially larger, recurring, or impulse purchases — not to feel guilty about a $5 coffee.
Why does the calculator use a real return, and what should I enter?+
A real return is the nominal market return minus inflation, so every result stays in today's purchasing power — the $7,612 that a $1,000 purchase could become in 30 years is $7,612 of today's dollars, directly comparable to the price. Many planners use 4–7% real as a long-run guide for a diversified stock portfolio (the calculator suggests 7%, near the long-run US historical average), but future returns are uncertain and a lower assumption gives you a margin of safety. The result scales directly with this input, so try a pessimistic and an optimistic value to see the range rather than trusting a single number.
Does a 37-day FIRE delay mean I shouldn't buy the thing?+
No — the number is information, not a verdict. Spending money on things you value is the point of having it, and a purchase that delays financial independence by a month may be entirely worth a month. The delay simply prices the trade-off in units of your own freedom instead of dollars, which many people find more meaningful than an abstract future value. It also compounds in reverse: recurring purchases repeat the delay every time, which is where the arithmetic gets serious. This model assumes a constant return and steady contributions, ignores taxes and fees, and is informational only — not financial advice.