Matemática

Percentage Increase & Decrease Calculator

Calculate % change between two numbers instantly. Formula: ((New − Old) / Old) × 100. Includes a reference table of common increases and decreases. Free, instant results.

🗓️ Updated June 2026 Reviewed by Martín Rodríguez

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Reviewed by: Martín Rodríguez (editorial policy ) · Last reviewed: Jun 16, 2026

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Whether you're tracking a price hike, a salary bump, or a drop in test scores, this calculator gives you the exact percentage change between any two numbers — or applies a known percentage change to a starting value. Enter two numbers and get the result, direction, and full calculation instantly.

When to use this calculator

Calculating how much a product's price increased or decreased after a sale or price change
Determining the percentage raise (or cut) in a salary or hourly wage
Measuring improvement or decline in test scores, KPIs, or sports statistics
Comparing year-over-year revenue or expense changes in a business report
Figuring out how much weight, distance, or time changed as a percentage
Applying a known percentage change (e.g., +15%) to a starting value to find the new number

Percent change from A to B

% change = (new − old) ÷ old × 100. Negative = decrease.

From	To	% change
100	120	+20%
100	75	−25%
50	80	+60%
200	150	−25%
80	100	+25%

How it works

Percentage Increase & Decrease: Formula and Examples

Percentage change measures the relative change between two values, expressed as a percentage of the original amount. It answers: "by what proportion did this number grow or shrink?"

Formula 1 — Find the % Change

% Change = ((New Value − Original Value) / Original Value) × 100

Positive result = increase

Negative result = decrease

Original value must not be zero (division by zero is undefined)

Formula 2 — Apply a Known % Change

New Value = Original Value × (1 + % Change / 100)

To find only the added/subtracted amount:

Difference = Original Value × (% Change / 100)

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Quick-Reference Table: Common % Changes from 100

Original	Change	New Value	% Change
100	+10%	110	+10%
100	+25%	125	+25%
100	+50%	150	+50%
100	+100%	200	+100%
100	−10%	90	−10%
100	−25%	75	−25%
100	−50%	50	−50%
200	→ 250	n/a	+25%
500	→ 400	n/a	−20%
1,000	→ 1,150	n/a	+15%

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Worked Examples

Scenario	Original	New	% Change
Price increase	$100	$120	+20%
Price decrease	$100	$80	−20%
Salary raise	$55,000	$60,500	+10%
Weight loss	200 lb	185 lb	−7.5%
Score drop	95	76	−20%
Revenue growth	$1,200	$1,560	+30%

Walkthrough — $100 to $120:

% Change = ((120 − 100) / 100) × 100
         = (20 / 100) × 100
         = +20%  (Increase)

Walkthrough — apply +15% to $200:

New Value = 200 × (1 + 15/100)
          = 200 × 1.15
          = $230  (Difference = $30)

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Important Distinctions

Percentage change vs. percentage points: If an interest rate rises from 2% to 3%, that is +1 percentage point but a 50% increase in the rate itself. This calculator computes percentage change, not percentage-point difference.

Symmetry warning: A 20% increase followed by a 20% decrease does NOT return to the original. Example: $100 → $120 (+20%) → $96 (−20% of $120). To fully reverse a P% increase, you must decrease by P/(1 + P/100) percent.

Zero as original value: Division by zero is undefined. If the starting value is 0, only the absolute change can be reported, not a percentage.

Frequently asked questions

What is the formula for percentage increase?

% Increase = ((New Value − Original Value) / Original Value) × 100. Example: $80 to $100 → ((100 − 80) / 80) × 100 = 25% increase. The original (starting) value is always the denominator.

What is the formula for percentage decrease?

It's the same formula: ((New − Original) / Original) × 100. When the new value is smaller, the result is negative. Example: $100 to $75 → ((75 − 100) / 100) × 100 = −25% decrease.

Is a 50% increase the same as a 50% decrease in reverse?

No. If a price rises 50% from $100 to $150, a 50% decrease from $150 brings it to $75 — not $100. To reverse a P% increase you need to decrease by P/(1 + P/100) percent. For 50%: 50/(1.50) ≈ 33.3% decrease.

What's the difference between percentage change and percentage points?

Percentage points measure the arithmetic difference between two percentages (5% to 8% = +3 percentage points). Percentage change measures the relative change: (8−5)/5 × 100 = 60% increase. Always clarify which one you mean in financial or statistical contexts.

What does a 100% increase mean?

A 100% increase means the value doubled. Original × (1 + 1.00) = Original × 2. Example: $50 increased by 100% = $100. A 200% increase means it tripled: $50 → $150.

How do I apply a percentage increase to a number?

Multiply the original by (1 + rate). For a 15% increase: New = Original × 1.15. For a 15% decrease: New = Original × 0.85. The difference alone: Original × (rate / 100). Example: 15% of $200 = $30, so new value = $230.

Can I calculate percentage change when the original value is negative?

Mathematically yes, but interpret carefully. If original = −$200 and new = −$100, the formula gives a 50% increase in value. Whether that's meaningful depends on context — reducing a debt shows a positive % change even though you owe less.

Why can't I calculate percentage change from zero?

Because the formula divides by the original value. Division by zero is undefined. If your starting point is zero, you can only report the absolute change, not a percentage. The calculator flags this as 'Undefined'.

Is the % increase from $80 to $100 the same as the % decrease from $100 to $80?

No. $80 to $100 is a 25% increase ((20/80)×100). $100 to $80 is a 20% decrease ((20/100)×100). The base value differs, so the percentages differ even though the absolute change is $20 in both cases.

How is percentage change different from finding a percentage of a number?

'20% of $500' (= $100) gives a portion of one number. Percentage change compares two different values to measure relative movement. They use different formulas and answer different questions — this calculator handles percentage change between two values.

Sources & references

Percent Change — Khan Academy — Khan Academy (2026)
Consumer Price Index (CPI) Percent Changes — U.S. Bureau of Labor Statistics — U.S. Bureau of Labor Statistics (2026)
Percentage Change — Math Is Fun — Math Is Fun (2026)

Methodology & trust

Editorial

Calculadora de matemática revisada por el equipo editorial de Hacé Cuentas, contrastada con Percent Change — Khan Academy, según nuestra política editorial y metodología.

Updates

Última revisión: June 16, 2026. Los parámetros se verifican periódicamente con las fuentes citadas.

Privacy

Calculations run 100% in your browser. We do not store or transmit your data.

Limitations

Indicative results. For critical decisions, consult a professional.

📌 How to cite this calculator

Rodríguez, M. (2026). Percentage Increase & Decrease Calculator. Hacé Cuentas. https://hacecuentas.com/percentage-increase-decrease-calculator

Contenido bajo licencia CC-BY 4.0 — reutilizable citando la fuente con enlace a Hacé Cuentas.

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