About the 100 Envelope Challenge Tracker
The 100 envelope challenge is a simple savings game: number 100 envelopes from 1 to 100, shuffle them, and each time you draw one, put that many dollars inside. When every envelope is full you will have saved $5,050. This tracker does the bookkeeping — type in the envelope numbers you have already filled, and it shows how much you have saved, how much is left, how far through you are and how long the rest will take at your pace.
It also draws your next envelopes for you. The draw is random but reproducible: it is generated from the seed text you choose and the envelopes you have already done, so the same inputs always give the same picks, and new picks appear as you log progress. Use the multiplier to make the challenge easier ($0.50 per number for $2,525) or bigger ($2 per number for $10,100), or change the number of envelopes to run a shorter or longer version.
A common pace is two envelopes a week, which finishes in 50 weeks; one a day finishes in about three months but needs around $350 a week on average. Because the amounts are random, some weeks cost far more than others — if you draw two high numbers in a tight week, swap one for a low number and keep going. The point is building the habit.
With the default inputs, the saved so far is $0.00. Change any value above to recalculate instantly.
How to use the 100 envelope challenge tracker
- 1Choose a multiplier — $1 per number saves $5,050 over 100 envelopes.
- 2Set how many envelopes you will fill each week.
- 3Each time you fill an envelope, add its number to the list.
- 4Check your saved amount, what is left and the weeks remaining.
- 5Use the next-envelope picks for your coming draws (change the seed for a different order).
Formula and method
Envelopes numbered 1 to N add up to N(N + 1) ÷ 2, which is 5,050 for 100 envelopes, so the goal is that total times the dollars-per-number multiplier m. What you have saved is the sum of the envelope numbers you have filled times m, and the rest is simply the goal minus that amount.
The time to finish divides the envelopes left by your weekly pace, and the average needed per week is the money left times the pace divided by the envelopes left (the average value of the remaining envelopes times how many you open each week). The next draw is a seeded shuffle of the envelopes you have not filled, so it is random but repeatable.
- N
- Number of envelopes (100 in the classic challenge)
- m
- Dollars per envelope number
- pace
- Envelopes you fill per week
Worked examples
Just starting at 2 envelopes a week
The classic challenge saves 1 + 2 + … + 100 = $5,050. At two envelopes a week it takes 50 weeks, which averages $101 a week (two envelopes worth $50.50 each on average).
Seven envelopes filled
Envelopes 1, 5, 10, 25, 50, 75 and 100 add up to $266, or 5.3% of the goal. The 93 envelopes left take 46.5 weeks at two a week, averaging about $102.88 a week because the numbers left are slightly higher than average.
Half-size challenge, one envelope a day
At $0.50 per number the goal is $2,525. The duplicate 3 and the out-of-range 200 are ignored, so envelopes 3 and 12 count for $7.50. The remaining 98 envelopes take 14 weeks at one a day.
Frequently asked questions
How much do you save with the 100 envelope challenge?+
Filling envelopes numbered 1 to 100 with that many dollars saves $5,050 in total, because 1 + 2 + … + 100 = 5,050. A half-size version at $0.50 per number saves $2,525.
How long does the 100 envelope challenge take?+
It depends on your pace. One envelope a day takes 100 days (about 14 weeks), while two envelopes a week takes 50 weeks — roughly a year. Expect to need about $101 a week on average at two a week.
How do I do the 100 envelope challenge without real envelopes?+
Use this tracker or a numbered list instead: draw a random number each time, transfer that amount to a separate savings account, and log the number as filled. Many people prefer this to keeping cash at home.
What if I draw a big envelope in a tight week?+
Put it back and draw a smaller one, or split the amount over two weeks. The total stays the same as long as every number is eventually filled, and keeping the habit matters more than strict order.
Is the 100 envelope challenge better than the 52-week challenge?+
The 100 envelope challenge saves more ($5,050 versus $1,378 for the classic 52-week challenge) and has random weekly amounts. The 52-week challenge is gentler and more predictable, rising by $1 each week.