Percentage Calculator

What is a Percentage Calculator?

This calculator solves the three most common percentage problems in one tool. Pick a mode, enter two numbers, and get an instant result — no formulas to remember.

How to Calculate Percentages

The calculator has three modes. Tap a mode button to switch:

Mode 1: X% of Y

Finds a specific percentage of a number. Enter the total value and the percentage you want to calculate.

Mode 2: X is what % of Y

Finds what percentage one number is of another. Enter the partial value and the total value.

Mode 3: % Change

Finds the percentage increase or decrease between two values. Enter the original value and the new value. A positive result means an increase; negative means a decrease.

What the Result Means

Mode	Result	Example
X% of Y	The calculated amount (number)	15% of 200 = 30
X is what % of Y	The ratio as a percentage	45 is what % of 60 = 75%
% Change	The percentage increase or decrease	From 50 to 40 = -20%

Good Examples

Example 1: Restaurant Tip (X% of Y)

You want to leave a 18% tip on a $85 dinner bill.

• Mode: X% of Y
• Total Value (Y): 85
• Percentage (X%): 18
• Result: 15.3 — your tip is $15.30

Example 2: Test Score (X is what % of Y)

You scored 42 out of 55 on a quiz. What’s your grade?

• Mode: X is what % of Y
• Partial Value (X): 42
• Total Value (Y): 55
• Result: 76.36% — your grade is about 76%

Example 3: Salary Raise (% Change)

Your annual salary went from $52,000 to$55,640.

• Mode: % Change
• Original Value (X): 52000
• New Value (Y): 55640
• Result: +7% — you got a 7% raise

Example 4: Shopping Discount (% Change)

A shirt was $80, now marked down to$56.

• Mode: % Change
• Original Value (X): 80
• New Value (Y): 56
• Result: -30% — it’s a 30% discount

Example 5: Loan Down Payment (X% of Y)

A car costs $28,000 and the dealer requires 15% down.

• Mode: X% of Y
• Total Value (Y): 28000
• Percentage (X%): 15
• Result: 4,200 — you need $4,200 upfront

Percentages in Daily Life

Tax

Sales tax is a percentage of the purchase price. If your local sales tax is 8.5%, an item priced at $50 will cost$50 + (8.5% of $50) =$54.25 at the register.

Tips

Tipping typically ranges from 15% to 20% of the pre-tax bill. Quick trick: find 10% (move the decimal point left), then add half of that for 15%, or double it for 20%.

Grades

A score of 42 out of 50 equals 84%. Use Mode 2 to convert any score into a percentage instantly.

Inflation

If inflation is 3% per year, something that costs $100 today would cost approximately$134 in 10 years — a cumulative increase of 34%.

Key Tips

Increase vs decrease — direction matters. A 50% increase followed by a 50% decrease does NOT get you back to the original. $100 → +50$150 → -50% = $75. The base value changes after each step.

Quick mental math. To find 10% of any number, move the decimal point one place left. 10% of 250 = 25. Then 5% = half of that = 12.5.

Percentage points vs percentages. “Interest rate rose from 3% to 5%” — that’s a 2 percentage point increase, but a 66.7% percentage increase. These are not the same thing.

Formulas

Mode	Formula
X% of Y	$\frac{X}{100} \times Y$
X is what % of Y	$\frac{X}{Y} \times 100$
% Change	$\frac{Y - X}{\|X\|} \times 100$

Frequently Asked Questions

Can percentages be greater than 100%?

Yes. A percentage over 100% means the value exceeds the reference amount. If revenue grew from $1M to$2.5M, that’s a 150% increase.

Why does the calculator show negative percentages?

In % Change mode, a negative result means a decrease. Going from 80 to 60 gives -25%, indicating a 25% drop.

How do I convert a fraction to a percentage?

Divide the numerator by the denominator, then multiply by 100. For example, 3/8 = 0.375 × 100 = 37.5%. Or use Mode 2: enter 3 as X and 8 as Y.

What is the difference between percentage change and percentage points?

If an interest rate moves from 5% to 8%, the increase is 3 percentage points. But the percentage change is 60%, because (8 - 5) / 5 × 100 = 60%.