Percentage Increase Calculator

How to use this calculator

1. Enter the starting (old) value.
2. Enter the new value.
3. The result is the signed percentage increase; a negative result means the value actually fell.

The formula

New

The value after the change

Old

The starting value (cannot be zero)

How it works

The increase is measured relative to where you started. Going from 80 to 100 is a gain of 20 on a base of 80, which is 20 ÷ 80 = 0.25, or 25%.

To apply a percentage increase to a number, multiply by (1 + percentage/100). A 25% increase on 80 is 80 × 1.25 = 100.

Why the starting value is the base

Percentage increase is always measured against the original, earlier, or baseline value — never the new one. Dividing by the wrong number is the single most common mistake, and it always understates growth. Going from 40 to 50 is a 25% increase (10 ÷ 40), not a 20% increase (10 ÷ 50). The latter is the percentage decrease you would need to get back from 50 to 40.

This asymmetry means increases and decreases of the same size are not mirror images. A 50% rise is undone by a 33.3% fall, and a 100% rise is undone by a 50% fall.

Comparing growth over different time spans

A total percentage increase says nothing about how long it took. Growth of 60% over six years is not comparable to 60% in six months. When periods differ, convert to an annualised rate by taking the compound growth rate rather than dividing the total increase by the number of years, which overstates early growth and understates late growth.

For repeated period-on-period growth, the compound interest calculator on this site handles the exponentiation for you and shows the resulting end value.

Practical uses and how to present the number

When reporting an increase, state both the absolute change and the percentage. "Revenue rose $120,000, up 18%" is far more informative than either figure alone, and it prevents small bases from producing dramatic-looking percentages that mislead readers.

Round sensibly. Quoting an increase to four decimal places implies a precision the underlying data rarely supports; one decimal place is enough for almost every business or personal use.

Absolute change versus relative change

Every increase has two honest descriptions. The absolute change is the raw difference — a salary going from 40,000 to 44,000 rose by 4,000. The relative change expresses that difference against the starting point: 4,000 / 40,000 = 10%.

Neither is more correct; they answer different questions. Absolute change matters when the unit itself is what you care about, such as budget headroom in currency. Relative change matters when you want to compare items of different sizes.

Report both when the audience needs context. A 200% increase in incidents sounds alarming until you learn it means the count went from one to three.

Compound growth and annualised rates

When something grows repeatedly, the increases multiply. Three consecutive 10% rises give 1.1 x 1.1 x 1.1 = 1.331, a 33.1% total rise, not 30%. The gap widens quickly with larger rates and more periods.

To convert a total increase across several periods into a per-period rate, take the nth root of the growth factor. A 33.1% rise over three years is the cube root of 1.331 = 1.10, meaning 10% per year.

This annualised figure is what lets you compare a two-year gain with a five-year one fairly. Comparing raw totals across different time spans is the most common way growth numbers mislead.

Common mistakes when measuring increases

Using the ending value as the base is the classic slip. Going from 80 to 100 is a 25% increase (20 / 80), not 20%. The base is always where you started.

Starting from zero makes percentage increase undefined — dividing by zero has no answer. Describe the change in absolute terms instead: 'from 0 to 12', not 'up infinity percent'.

Mixing units or seasonal periods also distorts results. Comparing a December figure with a November one in a seasonal business measures the season, not the trend; compare like periods year on year instead.

Reading growth figures critically

Ask what the base was. Large percentage increases on small bases are common and rarely meaningful on their own. Ask over what period the change occurred, and whether the period was chosen to flatter the result.

Ask whether the figure is adjusted for inflation. A 4% pay rise in a year of 6% inflation is a real-terms cut, even though the nominal number went up.

Ask whether the comparison is like for like. Changes in measurement method, product mix, or how a metric is defined can create apparent growth with no underlying change at all.

Worked examples across contexts

Rent rises from 1,150 to 1,265: the change is 115, and 115 / 1,150 = 0.10, a 10% increase. Multiplying the old rent by 1.10 confirms the new figure.

Website visits go from 8,400 to 11,760: the change is 3,360, and 3,360 / 8,400 = 0.40, a 40% increase. Over four months that is roughly 8.8% per month compounded.

A recipe scaling from four to six servings is a 50% increase, so every ingredient multiplies by 1.5. Percentage increase is the same operation whether the unit is money, people, or grams of flour.

Glossary and verification

Original value: the starting point and the base of the calculation. New value: the ending amount. Growth factor: new / original, expressed as a multiplier such as 1.10.

To check any result, multiply the original by (1 + rate / 100) and confirm you land on the new value. If you do not, the base was probably wrong.

For repeated growth, check by applying the per-period rate the stated number of times rather than multiplying the rate by the number of periods.

Reading growth figures in the wild

Published growth numbers rarely state their baseline clearly, and the same underlying change can be dressed up as a large or a modest increase depending on which starting value the writer selects. Always locate the original figure before accepting a headline percentage.

Year-on-year and month-on-month increases answer different questions: the first strips out seasonal swings, the second captures momentum but is noisy. Quoting one when the reader expects the other is a common source of confusion.

When a figure rises from a very small base, the percentage increase can look dramatic while the absolute change stays trivial. Reporting both the percentage and the raw difference keeps the picture honest.

If a series is rebased or redefined partway through, percentage increases across the break are not comparable. Note the discontinuity rather than calculating straight through it.

Compounding successive increases

Two consecutive increases of ten percent do not total twenty percent, because the second applies to the already-raised value. The combined effect is twenty-one percent, and the gap widens as the individual increases grow.

To chain increases, convert each to a multiplier, multiply them together, then subtract one. A rise of five percent followed by eight percent gives 1.05 times 1.08, or a 13.4 percent total increase.

This matters most for salaries, rents, and subscription prices, where several modest annual increases quietly compound into a large cumulative change over a handful of years.

Reversing the order of the increases produces exactly the same total, which is a useful check on any chained calculation you perform by hand.

Presenting increases so readers trust them

State the starting value, the ending value, and the percentage together. A reader who can see all three can verify your arithmetic in seconds and is far more likely to accept the conclusion.

Round percentages consistently, usually to one decimal place, and never round the inputs before dividing — rounding early is the most frequent cause of a figure that a careful reader cannot reproduce.

Where the increase covers more than one period, say whether the figure is cumulative or annualised, since the two can differ substantially over long spans.

Charts should start the vertical axis at zero when showing absolute values; truncated axes exaggerate increases that the percentage itself already describes accurately.

When this calculator is useful

• Price and rent changes
• Salary raises
• Growth in savings or traffic
• Year-over-year comparisons