How does the 100 envelope challenge work

The rules in one minute

The setup is a stack of envelopes numbered 1 through 100. Thrivent's description of the challenge is typical: pull one envelope at random each day, and whatever number is written on it is the amount of cash that goes inside. Envelope 7 gets $7, envelope 82 gets $82. A filled envelope is done, so every amount comes up exactly once.

The challenge spread on TikTok. In January 2023, TIME reported that its hashtag had gained over 150 million views, and profiled Jasmine Taylor, founder of Baddies & Budgets, who had completed it three times since starting in July 2021 and saved over $15,000 along the way.

Nothing in the rules requires a bank, an app or a sign-up. Most people keep the envelopes in a box or a ring binder. Thrivent also mentions skipping cash entirely: use an online random number generator instead of envelopes and transfer the chosen amount into a savings account each day.

Where $5,050 comes from

Adding 1 through 100 is the classic pairing trick. Match the first and last numbers (1 + 100), then the second and second-to-last (2 + 99), and so on. Each of the 50 pairs adds up to 101, and 50 times 101 is 5,050. The general rule is n × (n + 1) ÷ 2, which is useful if you want to resize the challenge later.

The average envelope holds $50.50, and that figure matters more than the total because it tells you what each draw costs on average. At one envelope a day, an average week comes to about $353.50. At one envelope a week, it is $50.50.

Drawing at random spreads the big amounts out, but it does not make them smaller. Half of the envelopes hold $51 or more, and one of them is a $100 day. Knowing that before you start makes the large draws feel like part of the plan rather than a setback.

Choosing a pace

One a day: 100 days. This is the version Thrivent describes as saving $5,050 over three months, and it is the most demanding. If you go in numerical order instead of drawing at random, the last 30 envelopes (71 to 100) add up to $2,565, which is the more than $2,500 in the final month that Taylor mentions to TIME when she suggests a slower pace.

Two a week: 50 weeks. Taylor told TIME she recommends two envelopes per week for people with smaller budgets who cannot save for 100 days in a row. It finishes in just under a year and averages about $101 a week.

One a week: 100 weeks. Thrivent mentions pulling envelopes weekly instead of daily when the daily pace is too fast. At an average of $50.50 a week, it finishes a little short of two years. If you are paid every two weeks, matching the draws to payday works too: 100 envelopes spread over 26 paychecks is three or four envelopes per payday, about $194 per paycheck on average.

Making it smaller or bigger

Because the total follows n × (n + 1) ÷ 2, shortening the range cuts it quickly. Baddies & Budgets points out that numbering the envelopes 1 to 50 still gets you $1,275. Done at one envelope a week, that is a 50-week challenge averaging $25.50 a week.

Going the other way, doubling every amount ($2 to $200) makes $10,100. Thrivent's general advice is that starting with smaller amounts or allowing more time can feel more manageable and still get you to the same result.

For envelopes you cannot cover on the day, Taylor's advice in TIME is simple: put in whatever amount you can. The challenge is a structure for saving, not a contract with a penalty clause.

Where the cash sits while you save

For many people the envelopes are the point. Watching a stack of cash get thicker is the motivation. They also come with trade-offs. Thrivent lists not earning interest among the drawbacks, noting that cash-based challenges do not benefit from interest the way a high-yield savings account or certificate of deposit can.

Cash at home also sits outside deposit insurance. The FDIC insures deposits at insured banks up to $250,000 per depositor, per bank, for each account ownership category, and that coverage applies to deposits such as checking and savings accounts, not to bills in a binder. Accredited financial counselor Jen Hemphill, quoted by TIME, suggested depositing the cash into a high-yield savings account as you go along. You can also combine the two: fill the envelope, then move its contents to savings on a set day each week.

This guide explains how a popular savings challenge works. It is general information, not financial advice.

Common mistakes

Going in numerical order. Order puts every large envelope at the end, when enthusiasm is usually lowest. Drawing at random, the method both Thrivent and TIME describe, mixes $3 days with $96 days from the start.

Buying an expensive kit first. TIME noted that one popular envelope binder kit cost $49.90 plus shipping. That is about what the first nine or ten envelopes add up to, spent before you have saved anything. Plain envelopes or a printed chart do the same job.

Losing track. With a box of half-filled envelopes it is easy to forget which numbers have come up, or to cross off the wrong square on a chart. Mark each number the moment it is drawn, and again when the money is actually set aside.

Treating a missed day as failure. Nothing in the rules punishes a gap, and switching to the two-a-week pace keeps the total intact. If you would rather keep the grid on your phone, Envelo shows the 100 envelopes as a grid you scratch open one at a time; the amount is drawn at random from the ones not used yet, and an envelope turns green only after you mark the cash as stashed. The app never holds or moves money.

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