Jar Savings Calculator

The jar on the kitchen counter is the oldest savings product there is, and the arithmetic behind it is one multiplication:

Total saved = amount per day × number of days

That is all this page does. What makes it worth running is that almost nobody guesses the answer correctly. Small daily amounts feel like nothing and the year-end total is a number people do not believe until they see it written down.

What a daily habit turns into:

Worked example. Put $5 in the jar every day for a year. That is $35 a week, about $150 a month, and $1,825 by the end of the year. Enter 5 and 365 above and those are the four figures you get back. It is roughly the price of a decent laptop, assembled entirely out of loose change and single notes.

Three things worth knowing before you commit to a jar.

Cash in a jar earns nothing, and quietly loses value. At 3% inflation, $1,825 sitting in a jar for a year is worth about $1,770 in the money you started with. Over one year that is tolerable; over five it is not. A jar is a good place to collect and a bad place to keep, so bank it a few times a year.

Coin-counting machines take a cut. The Coinstar-style kiosks in supermarkets charge somewhere around 12% to turn coins into cash, which on a year of loose change is a genuinely painful bite. Most banks and credit unions will still take rolled coin from an account holder for nothing, and paper coin wrappers are usually free at the counter. Rolling coins in front of the television is dull, but 12% of $1,825 is $219.

The frequency matters more than the amount. A dollar a day beats a lump of $30 once a month, not because of the arithmetic (they are identical) but because the daily version survives a bad month. Habits that need a decision every time tend to stop; habits attached to something you already do every day tend not to.

A variation that works better for most people. Instead of a fixed daily amount, round every card purchase up to the next dollar and move the difference. Enter your rough daily spend as the amount and you will land near the same total. Several banks automate this now, which removes the one hard part.