How the 100 envelope challenge works (and why it adds up to $5,050)
Short answer
Number 100 envelopes from 1 to 100. Each time you save, pick an envelope and put in its number in dollars: envelope 37 gets $37. Order doesn't matter. When all 100 are full you've saved $5,050. A tracker sheet with all 100 amounts lets you colour each one in, so you always know which are left without opening envelopes.
The rules, such as they are
- Label 100 envelopes 1 to 100.
- When you save, choose any envelope that's still empty.
- Put in that envelope's number in dollars.
- Repeat until all 100 are filled.
The choice is the useful part. On a tight week you pick envelope 4. On payday you pick 88. You still finish at the same total.
Where $5,050 comes from
1 + 2 + 3 + … + 100 = 5,050. Pair the numbers from the ends: 1 + 100, 2 + 99, 3 + 98, and so on. That's 50 pairs that each make 101, and 50 × 101 = 5,050. The average envelope holds $50.50.
Smaller and bigger versions
$5,050 is a lot for some budgets and not much for others. Change the number of envelopes or the step between them:
| Envelopes | Step | Biggest envelope | Total |
|---|---|---|---|
| 50 | $1 | $50 | $1,275 |
| 100 | $0.50 | $50 | $2,525 |
| 100 | $1 | $100 | $5,050 |
| 100 | $2 | $200 | $10,100 |
| 200 | $1 | $200 | $20,100 |
Picking a pace
- One a day: 100 days, so a little over three months.
- Two a week: 50 weeks, close to a year.
- One a week: 100 weeks, almost two years.
A mix works too: small envelopes on ordinary days, a big one whenever extra money comes in.
Cash or not
The name comes from cash in paper envelopes, and that version still works. If you'd rather not keep cash at home, transfer each amount to a savings account and colour in the matching box on a chart. The chart becomes the envelopes.
Print a tracker for your version
In the Streaksheet builder, open Savings challenge and choose Envelopes. Set how many (1 to 200) and the step, and add what you're saving for if you like. You get a chart with every amount in a box to colour in, in any order; a deposit log with a running total; and a goal thermometer marked every 5%. The builder shows the total as you type.
You can see every sheet before paying. Printing is $7 for 31 days or $5 a month, and Streaksheet only prints the sheets: it doesn't hold or move money.
Build your envelope chart →Questions
How much money is the 100 envelope challenge?
$5,050 with $1 steps. That's 1 + 2 + 3 + … + 100.
How long does it take?
As long as you choose. One envelope a day takes 100 days; two a week takes 50 weeks.
Do I need real envelopes?
No. You can transfer each amount to a savings account and colour in the matching box on the chart instead.
Can I do fewer envelopes or smaller amounts?
Yes. In the Streaksheet builder you set the number of envelopes (1 to 200) and the step. 50 envelopes at $1 totals $1,275; 100 at 50 cents totals $2,525.
Does the deposit log work if I fill envelopes out of order?
The log lists envelopes in number order, so its running total column only matches if you go in order. If you jump around, tick the ✓ box for each envelope you fill and use the chart to see what's left.