The 100 envelope challenge on one monthly check or a fixed income
Short answer
You do not need a paycheck every week. Number 100 envelopes (or chart boxes) from 1 to 100 and fill some of them once a month, on the day your check lands. The full challenge is $5,050. Spread over 12 months that is $420.83 a month on average, about 8 envelopes a month. If that is too much, use a smaller step: at $0.50 the whole challenge is $2,525, or $210.42 a month over 12 months.
Pick the monthly amount first
The usual advice is to fill an envelope every day or week. On one check a month, flip that around:
- Decide what amount you will put in each month. Do the arithmetic against your own numbers.
- On check day, pick any empty envelopes whose numbers add up to about that amount.
- Colour those boxes in on the chart. Leave the rest.
- Next month, repeat. The challenge ends when all 100 boxes are coloured.
Because the order is free, a month with less to spare gets small envelopes (1, 2, 3) and a bigger month gets the big ones. Nothing is behind or late.
Build the chart for your step →
$5,050 split across months
These are plain averages: the total divided by the number of months. Each month's real amount depends on which envelopes you pick, and the last month may be a partial one.
| Months | Envelopes a month | Average a month, $1 step ($5,050) | Average a month, $0.50 step ($2,525) |
|---|---|---|---|
| 6 | 16.7 | $841.67 | $420.83 |
| 10 | 10.0 | $505 | $252.50 |
| 12 | 8.3 | $420.83 | $210.42 |
| 18 | 5.6 | $280.56 | $140.28 |
| 24 | 4.2 | $210.42 | $105.21 |
| 36 | 2.8 | $140.28 | $70.14 |
Check one row: 12 months at a $1 step is $5,050 ÷ 12 = $420.83, and 100 ÷ 12 is 8.3 envelopes a month.
Reduced versions and their totals
Envelope n holds n times the step, so the total is the step × (count × (count + 1) ÷ 2). Halve the step and the total halves.
| Version | Total | Biggest envelope |
|---|---|---|
| 100 envelopes, $1 step | $5,050 | $100 |
| 100 envelopes, $0.50 step | $2,525 | $50 |
| 100 envelopes, $0.25 step | $1,262.50 | $25 |
| 100 envelopes, $0.10 step | $505 | $10 |
| 50 envelopes, $1 step | $1,275 | $50 |
| 50 envelopes, $0.50 step | $637.50 | $25 |
| 50 envelopes, $0.25 step | $318.75 | $12.50 |
How many months a fixed monthly amount takes
Going the other way: if you can put in the same amount every month, this is the number of months to reach the full total, rounded up to a whole month.
| Put in each month | Months, $1 step ($5,050) | Months, $0.50 step ($2,525) |
|---|---|---|
| $25 | 202 | 101 |
| $50 | 101 | 51 |
| $100 | 51 | 26 |
| $150 | 34 | 17 |
| $200 | 26 | 13 |
| $250 | 21 | 11 |
| $500 | 11 | 6 |
Check one row: $200 a month into $5,050 is 25.25, so 26 months.
Keeping it simple on paper
- Use the chart, not envelopes, if you would rather not keep cash at home. Colour a box when the amount goes into your savings account.
- Write the date next to each month's boxes, so you can see at a glance where you stopped.
- Check your program's rules if your income comes from one.
Print a tracker for your version
In the Streaksheet builder, open Savings challenge, choose Envelopes, then set the number of envelopes (1 to 200) and the step, for example 0.50. 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, so you can check it against the tables above.
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
Can I do the 100 envelope challenge with one paycheck a month?
Yes. The challenge has no schedule. Fill whichever envelopes you can once a month, in any order, and stop when you reach the month's amount. The tables below show the arithmetic for 6 to 36 months.
How much is the 100 envelope challenge over 12 months?
With $1 steps, $5,050 over 12 months is $420.83 a month on average, about 8.3 envelopes a month. With $0.50 steps the total is $2,525, or $210.42 a month.
What if $5,050 is too much for my budget?
Shrink the step or the count. 100 envelopes at $0.50 totals $2,525; at $0.25 it totals $1,262.50; 50 envelopes at $1 totals $1,275. Set any step from one cent up in the builder.
Do I have to fill envelopes every week?
No. One session a month is enough. The chart shows which amounts are left, so you can skip months and pick up later.
Does the deposit log work if I fill envelopes out of order?
The log lists envelopes in number order, so its running total 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 is left.
Does Streaksheet hold the money?
No. It prints the sheets. The money goes wherever you keep your savings.