A change calculator has two common uses. In math and finance, it finds the percent change between an old value and a new value. At a register, it calculates how much change to give back and which bills and coins to use. Both are quick, everyday calculations that are easy to get wrong in your head.
For percent change, the formula is: percent change = ((new − old) Ă· old) Ă— 100. A positive result is an increase, a negative result a decrease. If a stock goes from $40 to $46, the change is (6 Ă· 40) Ă— 100 = 15 percent. If your phone battery drops from 80 percent to 60 percent, that’s a 25 percent decrease in charge, but a 20 percentage point drop.
For making change, subtract the price from the amount paid, then count out the largest bills and coins first. If an item costs $13.47 and the customer pays with a $20 bill, the change is $6.53: one $5 bill, one $1 bill, two quarters and three pennies. Many cashiers “count up” from the price to the amount paid, which helps avoid mistakes.
Tips: double-check the original value when calculating percent change, and don’t confuse percent change with percentage points. When making change, say the amounts out loud as you count them back.
Why use an online Change Calculator: it saves time, avoids simple arithmetic mistakes and shows each step, so you can check your homework, plan a project or make a decision with confidence. Bookmark the page so it’s ready the next time you need it.
Tips for getting accurate results from the Change Calculator: double-check that every input uses the right units, enter numbers without commas or symbols, and run the calculation a second time with a quick estimate in your head to confirm the answer looks reasonable.
Learn more about percent change on Wikipedia’s relative change article. Find percent increase, decrease and growth calculators on Minedit.