What does a small daily purchase really cost me over the years?
Enter what you spend and how often, and see what the same money would be worth if it were invested instead, and how much sooner it would get you to financial independence.
THE HABIT, INVESTED INSTEAD
$92k
At these inputs, $6 a purchase, 5 times a week, comes to $1,560 a year, or $48,360 over 31 years. Invested at the 3.9% a year this site plans with after inflation, the same money would be $92,305 in today’s dollars. Saved on top of what you already save, that money would bring financial independence 2 months sooner.
A year
$1,560
A month
$130
Spent in 31 years
$48,360
Sooner to FI
2 mo
UNDERSTAND YOUR RESULT
What you spend, and what the same money would grow to, in today’s dollars
Invested insteadSpent
After 31 years you will have spent $48,360; the same money invested at 3.9% a year after inflation would be $92,305 in today’s dollars, $43,945 of it growth.
The same $6 purchase at different frequencies, over 31 years
1 a week
$18k
2 a week
$37k
3 a week
$55k
5 a week
$92k
7 a week
$129k
14 a week
$258k
At $6 a purchase over 31 years, 1 a week would be $18,461 invested and 14 a week would be $258,453, in today’s dollars; yours is highlighted.
Year by year
| Year | Spent | Invested instead | Growth |
|---|---|---|---|
| 1 | $1,560 | $1,588 | $28 |
| 5 | $7,800 | $8,579 | $779 |
| 10 | $15,600 | $18,958 | $3,358 |
| 15 | $23,400 | $31,515 | $8,115 |
| 20 | $31,200 | $46,708 | $15,508 |
| 25 | $39,000 | $65,088 | $26,088 |
| 30 | $46,800 | $87,326 | $40,526 |
| 31 | $48,360 | $92,305 | $43,945 |
Growth is what the invested money earns on top of what you put in: $28 after 1 year, $43,945 after 31.
What moves the needle
Each row re-runs the calculation with one change. Click to apply.How it's computed
FORMULA
Yearly spend = price × purchases a week × 52
Monthly amount = yearly spend ÷ 12, invested at the end of each month
Real return = (1 + 7%) ÷ (1 + 3%) − 1, about 3.9% a year; monthly rate = (1 + real return)^(1/12) − 1
Value = monthly amount × ((1 + monthly rate)^months − 1) ÷ monthly rate — in today’s dollars
Sooner to FI = months to reach spending ÷ 4% without the money − months with it added to your monthly saving
- A year is 52 weeks, so five a week is 260 purchases. The money is treated as invested in equal amounts at the end of each month.
- Results are in today’s dollars: the money grows at 3.9% a year, the 7% this site plans with less 3% inflation. That is an assumption, not a forecast, and a real portfolio moves up and down.
- Prices are held constant in today’s dollars. Taxes and fees on the invested money are not modelled.
- The financial-independence comparison uses the FIRE pages’ model: your invested balance plus your monthly saving, growing at the real return until it reaches your yearly spending ÷ 4%. The habit’s money is added on top of what you already save.
- This is arithmetic on a habit, not advice to give it up. A purchase can be worth its price to you; the page only shows the price over time.
WORKED EXAMPLE · SAMPLE NUMBERS
$6 × 5 × 52 = $1,560 a year, $130 a month. Invested at the end of each of 372 months at 3.9% a year (0.3180% a month) it grows to $92,305 against $48,360 spent.
SOURCES
[1]Compound InterestInvestor.gov, U.S. Securities and Exchange Commission[2]Compound Interest CalculatorInvestor.gov, U.S. Securities and Exchange Commission[3]The Theory of InterestIrving Fisher, Macmillan, 1930 (real versus nominal interest)
[4]CPI-U, All Urban ConsumersU.S. Bureau of Labor StatisticsHSBuilt by Hussain Sehorewala · checked against worked examples · Sep 29, 2026
Keep this number honest as your life changes.
Put it on your Money Map and it re-runs as you change the seven numbers. It stays in this browser, and the calculator stays free.
Questions about this result
The idea that a small purchase you make often adds up to a large sum over the years, more so if the same money were invested. This page puts numbers on it: the yearly cost, the total over the years, and what the money would be worth invested at a real return of about 3.9% a year.
Seven $5 purchases a week for 52 weeks is $1,820 a year. Invested each month at a 3.9% real return for 30 years, that money would be about $101,880 in today’s dollars, against $54,600 spent.
Prices rise, so a dollar in 30 years buys less than a dollar today. The page grows the money at the return after inflation, so what you read is what it could buy at today’s prices.
No. It shows what a habit costs over time so the choice is a knowing one. A purchase that you enjoy or that saves you time can be worth its price. The levers show what a smaller habit would change.
It is this site’s planning assumption, a 7% return before inflation less 3% inflation, and not a forecast. Real returns vary from year to year and can be negative for long stretches. Try a lower number of years to see how sensitive the result is.
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