Percentage Increase Calculator

How to use the percentage increase calculator

1. Choose what you want to find. The default finds the percent change between an original value and a new one. The other two modes apply a percent to a value, or undo a percent to recover the value you started from.
2. Enter the values. For a decrease in the second and third modes, type the percent with a minus sign: −20 for a 20% drop.
3. Read the result. The headline tells you whether the change is an increase or a decrease. Underneath you get the plain difference, the new value as a percent of the old one, the percent change needed to get back, and the percent difference, a measure that doesn’t care which value came first.

The percent change formula

The divisor is the original value, not the new one, and not the larger of the two. That single choice is why a change from 26 to 36 and a change from 36 to 26 have different percentages even though the gap is 10 both ways.

The open textbook Prealgebra 2e from OpenStax works two examples in section 6.2:

• Increase (Example 6.23). Community college fees were proposed to rise from $26 to $36 per unit. The increase is $10, and 10 ÷ 26 = 0.3846, a 38.5% increase.
• Decrease (Example 6.24). Gas fell from $3.71 to $3.64 a gallon. The decrease is $0.07, and 0.07 ÷ 3.71 = 0.0189, a 1.9% decrease.

Run the first example backwards and you get 10 ÷ 36 = 27.8%. Undoing a 38.5% rise takes only a 27.8% cut, because the cut is measured from the larger number.

Applying a percent and finding the original

Raising or lowering by a percent. Multiply by one plus the percent as a decimal. A 15% increase on 26 is 26 × 1.15 = 29.90; a 20% decrease on 80 is 80 × 0.80 = 64. Working with the multiplier is quicker than finding the change and adding it, and it chains neatly.

Finding the original. Divide by the same multiplier. If a price is $120 after a 20% increase, the price before was 120 ÷ 1.20 = $100. A common mistake is to take 20% of $120 and subtract it, which gives $96. That is wrong because the 20% was figured on the old price, not the new one.

The same reverse step answers questions such as “what did this cost before tax?” or “what were sales last year if they are up 12% to $560,000?” The answer to the second is 560,000 ÷ 1.12 = $500,000.

Back-to-back changes don’t simply add

When one change follows another, multiply the multipliers instead of adding the percentages:

• Two 10% increases: 1.10 × 1.10 = 1.21, a 21% increase overall, not 20%.
• A 10% increase followed by a 10% decrease: 1.10 × 0.90 = 0.99, which leaves you 1% below where you began.
• A 25% increase followed by a 20% decrease: 1.25 × 0.80 = 1.00, back to the start exactly.

This is why a stock that falls 50% has to rise 100% to recover, and why a price cut and an equal-sized price rise don’t cancel out. The “change back to original” figure in the results shows the percentage needed to undo the change you entered.

Percent change or percent difference?

Percent change has a direction: there is an original value and a new value. Percent difference compares two values neither of which is the starting point, such as the prices at two stores or two lab measurements. It divides the gap by the average of the two values:

For 40 and 60, the gap is 20 and the average is 50, so the percent difference is 40%. The percent change from 40 to 60 is 50%, and from 60 to 40 it is −33.3%. If one of the values really is a “before,” use percent change. If you are comparing two things side by side, percent difference avoids picking a favorite.

Everyday examples

A pay raise. Going from $52,000 to $55,120 a year is a $3,120 rise, and 3,120 ÷ 52,000 = 6%. The pay raise calculator adds the per-paycheck amount and the inflation-adjusted figure.

Website traffic. Monthly visits up from 1,250 to 1,600 is 350 ÷ 1,250 = 28% growth.

Doubling and tripling. A value that doubles has risen 100%; one that triples has risen 200%. A fall of 100% means it has dropped to zero, and nothing can fall by more than that.

Rates. If a rate goes from 4% to 5%, that is one percentage point but a 25% increase in the rate itself. Say which one you mean when you report it.

Starting from zero. Percent change from 0 is undefined, because you can’t divide by zero. The calculator shows a dash. Report the plain difference instead, such as “up from 0 to 5 sales.”

Negative starting values. If the original is negative, such as a loss of −$20,000 turning into a profit of $5,000, the formula gives a misleading sign. Describe the change in dollars rather than as a percentage.

Growth over several periods

If a value grows from 1,000 to 1,331 over three years, the total change is 33.1%. The yearly rate is not 33.1 ÷ 3 = 11.03%, because each year’s growth builds on the year before. The steady yearly rate that produces the same result is found with a root:

Here (1,331 ÷ 1,000)^1/3 − 1 = 1.1 − 1 = 10% a year. Check it with the multipliers: 1.10 × 1.10 × 1.10 = 1.331. Dividing the total by the number of years overstates the yearly figure, and the gap widens as the total grows.

Use the simple percent change here for the total, then this formula when you need a per-month or per-year figure for comparison.

Percent change in a spreadsheet

With the original in A2 and the new value in B2, the formula is =(B2-A2)/A2, formatted as a percentage. To apply a change in C2 (entered as 15%), use =A2*(1+C2); to reverse one, use =B2/(1+C2). Rows that start at zero return a #DIV/0! error, which is the spreadsheet’s way of saying the percent change is undefined; report the plain difference for those rows instead. Copy the formula down the column and every row is measured against its own starting value.

Sources & assumptions

How this calculator gets its numbers. Full method: our methodology.

• Percent change = (new − original) ÷ original × 100, so the original value is the base.
• Applying a change multiplies by (1 + percent ÷ 100); reversing it divides by the same factor.
• Percent difference divides the absolute gap by the average of the two values.
• Percent change from 0 is undefined and is shown as a dash.

Sources

1. OpenStax (Rice University), Prealgebra 2e, 6.2 Solve General Applications of Percent. “Amount is percent of base” and Examples 6.14–6.20 (35% of 90 = 31.5; 36 is 75% of 48; 6.5% of $18 = $1.17; 9 is 25% of 36; an 18% tip on $68.50), plus percent increase and decrease in Examples 6.23 ($26 to $36, 38.5%) and 6.24 ($3.71 to $3.64, 1.9%).

Last reviewed November 2, 2026. Chained changes multiply rather than add, so report each step or the overall multiplier.