Percentage Calculator Find Increase & Decrease %

What is the percentage increase/decrease

Calculating percentages is something we all face in daily life — whether it’s checking exam marks, figuring out a salary or loan increase, tracking profit and growth, or even working out the off price during a sale. The problem is that manual percentage calculations can often feel confusing: What is the right formula? How do you quickly find the percentage difference, increase, or decrease without making mistakes?

That’s where an online Percentage Calculator becomes the perfect solution. With just a few clicks, you can instantly find percentages, calculate increases or reductions, and solve problems like Quick grade percentage, salary growth, or loan interest without stress. Our smart percentage calculator is designed to save time, avoid errors, and give accurate results — making percentage math simple for everyone.

What is Percentage Calculator?

Use this all-in-one percentage calculator to answer questions like “What percent of X is Y?”, “What is P% of X?”, “X is P% of what?”, and “How does a value change after an increase or decrease by P%?”

It’s built for real life—marks, discounted price (off price), profit, growth, salary raise, loan comparisons, and more. Just like a font generator helps you instantly create stylish text without effort, a percentage calculator quickly finds increases, decreases, and differences online with ease

How to use the Percentage Calculator (4 quick modes)

1. What is P% of X?

Enter the percent (P) and the number (X) → get the part (Y).
Example: 10% of 500 = 50.

2. X is what percent of Y?

Enter the part (X) and the whole (Y) → get percent (P).
Example: 27 of 30 marks → 27 ÷ 30 × 100 = 90%.

3. X is P% of what?

Enter the part (X) and the percent (P) → get the whole (Y).
Example: 10 is 5% of what? 10 ÷ 0.05 = 200.

4. What is X increased/decreased by P%?

Enter the start value (X) and choose increase or decrease by P. Examples:
Increase: 500 × (1 + 0.10) = 550
Decrease: 500 × (1 − 0.10) = 450

Tip: The tool solves any missing field automatically—type any two values, get the third.

Percentage Calculator cheat sheet (formulas & when to use)

Problem	Use when	Formula	Mini example
What is P% of X?	Find a part of a whole	Y = (P/100) × X	15% of 80 = 0.15 × 80 = 12
X is what percent of Y?	Compare part to whole	P = (X ÷ Y) × 100	1245 rent of 4000 salary → 31.125%
X is P% of what?	Find the whole from part & percent	Y = X ÷ (P/100)	10 is 5% of 200
Increase by P%	Markups, growth, salary raise	New = X × (1 + P/100)	100 ↑20% → 120
Decrease by P%	Discounts, reduction, off price	New = X × (1 − P/100)	200 ↓50% → 100
Percent change	Old to new (baseline is old)	`((New − Old) ÷	Old
Percent difference	Two values, no baseline	`	a − b
Percent error	Experimental vs theoretical	`	Exp − Theo

Worked examples (step-by-step)

1) Exam marks:

. You scored 27 out of 30.
. Percent = 27 ÷ 30 × 100 = 90%.

2) Off-price discount:

. An item was $48.89 after 10% off. What was the original price?
. Original = 48.89 ÷ (1 − 0.10) = 48.89 ÷ 0.9 = 54.322… ≈ $54.32

3) Profit percentage:

. Bought for $420, sold for $525. Profit = 525 − 420 = $105.
. Profit % = 105 ÷ 420 × 100 = 25%.

4) Salary raise:

. Salary goes from $100,000 to $120,000.
. Percent change = (120,000 − 100,000) ÷ 100,000 × 100 = 20%.

5) Loan comparison (rate drop):

. APR drops from 14% to 12%.
. Change = 2 percentage points (pp), not 2%.
. Relative change = (12 − 14) ÷ 14 × 100 = −14.29%.

6) Growth vs difference:

. Speed: 60 to 120. Percent change = (120 − 60)/60 × 100 = 100% (twice as fast).
. Percent difference of 60 vs 120 = |60 − 120| / ((60 + 120)/2) × 100 = 60 / 90 × 100 = 66.67%.

Percent change vs percent difference vs percent error

Use the right tool for the right question:

Percent change (increase/decrease): you have a start (old) and an end (new).
Example: sales grew from 800 to 920 → +15%.
Percent difference: two values with no clear baseline; you want a symmetric comparison.
Example: two quotes for a laptop: $950 vs $1000 → 5.13%.
Percent error: measured vs theoretical (science/quality).
Example: expected 100 g, measured 98 g → 2% error.

Percent change vs percent difference vs percent error

Conversions: percent ⇄ decimal ⇄ fraction

Percent → decimal: divide by 100.
15% → 0.15
Decimal → percent: multiply by 100.
0.156 → 15.6%
Fraction → percent: numerator ÷ denominator × 100.
4/5 → 0.8 → 80%
Percent → fraction: percent ÷ 100, simplify.
30% → 30/100 → 3/10

Percentage points (pp) vs percent (%)

Percentage points measure the absolute difference between two percentages.
10% → 12% is +2 pp.
Percent (%) change measures relative change.
10% → 12% is +20% relative to 10%.
Use pp for rates (interest, tax, polling). Use % for relative change.

Common pitfalls & pro tips

Don’t add yearly % changes straight across—use compounding.
+10% then −10% ≠ 0%; 100 → 110 → 99 (net −1%).
Choose the right baseline. For “percent change”, old is the denominator.
Round sensibly. Financial/marks often to 2 decimals; scientific values may require more.
Check units. “Off price” discounts, tax, profit, growth, salary, loan rates—keep contexts consistent.

Real-world uses (quick recipes)

Marks/grades: score ÷ total × 100.
Off price/discount: final = price × (1 − discount%).

Profit margin: Gross profit % = (Selling − Cost) ÷ Selling × 100.
Markup % = (Selling − Cost) ÷ Cost × 100.
Growth rate: (new − old) ÷ old × 100.
Salary raise: new = old × (1 + raise%).
Loan rate drop: report both pp and % change.
GST/VAT/Sales tax: tax = price × rate% → final = price + tax.

FAQs

A: A percentage expresses a ratio per hundred—a dimensionless way to compare parts to a whole.

A: Multiply: x/100 × y. Example: 12% of 250 = 0.12 × 250 = 30.

A: Divide then multiply by 100: x ÷ y × 100. Example: 45 of 60 → 75%.

A: whole = x ÷ (p/100). Example: 18 is 12% of 150.

A: original = discounted ÷ (1 − discount%). Example: 44 at 10% off → 44 ÷ 0.9 = 48.89.

A: 0.60 × 1260 = 756.

A: Use percent change when you have a before/after (old → new). Use percent difference when comparing two values with no baseline.

A: The absolute gap between two percentages. 4% → 6% is +2 pp (which is a +50% relative change).

A: Not reliably. Convert back to their underlying totals where possible, or use geometric means for growth rates.

Conclusion

Percentages power everyday decisions—from marks and salary to profit, growth, reduction, off price discounts, and loan comparisons. With the formulas above (and this calculator handling the math), you’ll move from guesswork to clarity in seconds using our percentage calculator. Bookmark this page, and use the four core modes to solve any percent question confidently.

Copy-ready snippet boxes (optional)

Percent of a number
Y = (P/100) × X

What percent is X of Y
P = (X ÷ Y) × 100

X is P% of what
Y = X ÷ (P/100)

Increase/Decrease by P%
New = X × (1 ± P/100)

Percent change
((New − Old) ÷ |Old|) × 100

Percent difference
|a − b| ÷ ((a + b)/2) × 100

Percent error
|Exp − Theo| ÷ |Theo| × 100