How to Calculate Percentage Increase – Formula & Examples

Percentage increase shows up everywhere: salary negotiations, electricity bills, bank profit rate announcements, inflation figures. Most people can spot when something has gone up — fewer can express that change precisely as a percentage. Here's the complete picture.

The formula

Percentage Increase = ((New Value − Old Value) ÷ Old Value) × 100

Three steps: subtract the old number from the new, divide that difference by the old number, multiply by 100. If the result is negative, the value went down — you're looking at a decrease, not an increase.

Worked examples

Salary increase

Your salary was Rs. 65,000. It went up to Rs. 75,000.

• Difference: 75,000 − 65,000 = 10,000
• Divide by original: 10,000 ÷ 65,000 = 0.1538
• Multiply by 100: 15.38%

A 15.4% raise. Quick mental check: 10,000 is roughly one-sixth of 65,000, and one-sixth is about 16% — close enough to confirm the answer makes sense.

Price change

A product cost Rs. 1,200 last month. Now it costs Rs. 1,560.

• Difference: 1,560 − 1,200 = 360
• Divide by original: 360 ÷ 1,200 = 0.30
• Multiply by 100: 30%

A 30% increase. Easy to verify: 30% of 1,200 is exactly 360.

Business revenue growth

Monthly sales went from Rs. 4,20,000 to Rs. 5,04,000.

• Difference: 5,04,000 − 4,20,000 = 84,000
• Divide by original: 84,000 ÷ 4,20,000 = 0.20
• Multiply by 100: 20%

20% month-on-month growth.

Percentage increase vs percentage points — an important distinction

If a bank's profit rate changes from 12% to 15%:

• It increased by 3 percentage points (15 minus 12)
• But that's a 25% increase in the rate itself (3 ÷ 12 × 100)

Both statements are correct — they're measuring different things. News articles sometimes use this ambiguity, particularly in reporting on interest rate changes. When you see a headline about rates rising, check whether it specifies percentage points or a percentage change — the meaning is very different.

Why reversing a percentage increase isn't straightforward

Many people assume that a 20% increase followed by a 20% decrease returns to the original. It doesn't.

Start with 100 → increase by 20% → 120 → decrease by 20% → 96. You end up lower than you started.

The reason: the second percentage applies to the new (higher) value, not the original. To reverse a 20% increase exactly, you need a 16.67% decrease. The formula: Decrease needed = (Increase% ÷ (100 + Increase%)) × 100.

Quick mental math shortcuts

• 10%: move the decimal point one place left — Rs. 8,500 → Rs. 850
• 5%: find 10%, then halve it — Rs. 850 ÷ 2 = Rs. 425
• 20%: find 10%, then double it — Rs. 850 × 2 = Rs. 1,700
• 25%: divide by 4 — Rs. 8,500 ÷ 4 = Rs. 2,125
• 15%: find 10%, find 5%, add them together

Common mistakes

• Dividing by the wrong number. Always divide by the original value, not the new one.
• Confusing percentage change with percentage points. State clearly which one you mean.
• Stacking discounts incorrectly. "50% off, then 20% off" is not 70% off. The second discount applies to the reduced price, not the original.