Decimal to Percent Converter — Convert Decimals to Percentages & Back

Decimal to Percent Converter — How to Convert Decimals & Percentages

The decimal to percent converter (also known as the convert decimal to percent calculator) lets you turn a decimal value into a percentage instantly. Because it calculates in both directions, you can also use it as a percent to decimal converter.

Read the sections below to learn how to convert decimals to percentages and percentages to decimals by hand, see worked examples, and understand what decimals and percentages actually mean.

What Are Decimals? – An Introduction

The Hindu–Arabic numeral system (also called the Indo-Arabic numeral system) is the decimal positional system — nowadays the most commonly used numeral system in the world. Other systems include binary and hexadecimal; you can convert between those using dedicated tools.

• "Decimal" means the system is based on 10.
• "Positional notation" means a symbol's value depends on its position. For example, the digit 3 in 13 equals 3, but in 342 it equals 300.

Using just ten symbols (0–9) we can represent any rational number. A four-digit number follows this general formula:

a₃a₂a₁a₀ = a₃×1,000 + a₂×100 + a₁×10 + a₀×1

Examples:

• 11 = 1×10 + 1×1
• 23 = 2×10 + 3×1
• 145 = 1×100 + 4×10 + 5×1
• 43 210 = 4×10 000 + 3×1 000 + 2×100 + 1×10 + 0×1

What about fractions? A decimal point (dot or comma) separates the whole part from the fractional part:

a₂a₁a₀.b₁b₂b₃ = a₂×100 + a₁×10 + a₀×1 + b₁/10 + b₂/100 + b₃/1 000

Examples:

• 376.49 = 3×100 + 7×10 + 6 + 4/10 + 9/100
• 0.321 = 3/10 + 2/100 + 1/1 000

What Are Percentages? – An Introduction

Percent means "out of a hundred" (from Latin per centum) and represents a ratio or number as a fraction of 100. We denote it with the percent sign %:

1% = 1/100

For example, 15% equals 15/100 and means "fifteen out of a hundred."

Examples in context:

• "40% of students are female" → if there are 100 students, 40 are girls.
• "You've eaten 20% of a bowl of 100 cornflakes" → you ate 20 flakes.

Percentages represent a ratio, not just a count. For example: 60% of 10 000 trees are deciduous → 60/100 × 10 000 = 6 000 deciduous trees.

How to Convert Decimal to Percent by Hand

The rule is simple: multiply the decimal by 100.

percent = decimal × 100

In practice, you move the decimal point two places to the right and add the % sign.

How to Turn a Decimal into a Percent — Examples

How to Convert Percent to a Decimal by Hand

The reverse rule: divide the percentage by 100.

decimal = percent ÷ 100

In practice, move the decimal point two places to the left and drop the % sign.

How to Turn a Percent into a Decimal — Examples

How to Use the Decimal to Percentage Converter

1. Choose the conversion mode:
   • Decimal → Percent — enter a decimal and get the percentage.
   • Percent → Decimal — enter a percentage and get the decimal.
2. Enter your value in the input field.
3. (Optional) Enter a base value and select a unit (currency, metric, or US/Imperial) to see the real-world result — e.g., how many dollars, kilograms, or miles the percentage represents.
4. Click Convert to see the result, the formula used, and — if you provided a base value — the applied amount.

Supported Units

• Currencies: USD ($), RUB (₽), EUR (€), GBP (£), JPY (¥), CNY (¥), CAD, AUD, CHF, INR, BRL, MXN, KRW, SEK, NOK, DKK, PLN, TRY, ZAR, SAR — 20 world currencies.
• Metric: m, cm, mm, km, kg, g, mg, t, L, mL, m², cm², km², ha, m³, cm³.
• US / Imperial: ft, in, yd, mi, lb, oz, gal, fl oz, qt, pt, ft², in², yd², mi², ac, ft³, in³.

Quick Reference: Common Decimal ↔ Percent Conversions

If you're working with fractions rather than decimals, check out our fraction-to-percent converter for a dedicated tool.