Percentage to Decimal Converter
Convert between percentages and decimals for calculations, finance, statistics, and everyday math. Bidirectional conversion with fraction equivalents.
How do I convert percentage to decimal?
Formula: Decimal = Percentage ÷ 100. Example: 25% = 25 ÷ 100 = 0.25. Simple method: Move decimal point 2 places left. 75% → 7.5 → 0.75. 5% → 0.5 → 0.05. 100% → 10.0 → 1.00. Common conversions: 50% = 0.5 (half). 25% = 0.25 (quarter). 10% = 0.1 (tenth). 1% = 0.01. 0.5% = 0.005. 150% = 1.5. Why: Decimals easier for calculations. Percentages easier to understand. Calculator uses decimals (0.25 × 100 = 25).
How do I convert decimal to percentage?
Formula: Percentage = Decimal × 100. Example: 0.75 = 0.75 × 100 = 75%. Simple method: Move decimal point 2 places right, add % sign. 0.5 → 05 → 50%. 0.125 → 12.5%. 1.5 → 150%. 0.03 → 3%. Common conversions: 0.5 = 50%. 0.25 = 25%. 0.1 = 10%. 0.01 = 1%. 1.0 = 100%. 2.0 = 200%. When to use: Converting calculator results to percentages. Interest rates (0.05 = 5% APR). Probability (0.75 = 75% chance). Test scores (0.85 = 85%).
What are common percentage to decimal conversions?
Essential conversions to memorize: 100% = 1.0 (whole). 75% = 0.75 (three quarters). 50% = 0.5 (half). 25% = 0.25 (quarter). 20% = 0.2 (fifth). 10% = 0.1 (tenth). 5% = 0.05. 1% = 0.01. Fractions: 33.33% = 0.3333 (one third). 66.67% = 0.6667 (two thirds). 12.5% = 0.125 (one eighth). Greater than 100%: 125% = 1.25. 150% = 1.5. 200% = 2.0. Less than 1%: 0.5% = 0.005. 0.1% = 0.001. Quick check: Decimal × 100 should equal percentage.
Why do we use decimals instead of percentages in calculations?
Decimals for calculations: Math operations: Multiplication/division easier with decimals. Example: 15% of 80. Wrong: 15 × 80 = 1200. Right: 0.15 × 80 = 12. Calculator compatibility: Calculators use decimal form. Programming/spreadsheets use decimals. Scientific notation uses decimals. Precision: Decimals show exact values. 0.333... vs 33.33%. Less ambiguous in formulas. When percentages better: Communication: "75% off" clearer than "0.75 off". Comparisons: 25% increase easier than 1.25 multiplier. Reports: People understand percentages. Best practice: Use percentages for presentation. Convert to decimals for calculation. Convert back to percentage for results.
How do I work with percentages greater than 100%?
Percentages over 100%: Meaning: More than the whole (original amount). 150% = 1.5 times the original. 200% = double the original. Examples: Sales increase 150%: New sales = 1.5 × old sales. If old = 100, new = 150. Stock up 200%: Now worth 3× original (original + 200% gain). Profit margin 120%: Selling price = 2.2 × cost. Conversion: 150% = 150 ÷ 100 = 1.5. 250% = 2.5. 1000% = 10.0. Common mistake: "200% more" vs "200% of". 200% more = 300% of original (3×). 200% of original = 2× original. Context matters: Growth, markup, increases often >100%.
What are real-world applications of percentage-decimal conversion?
Practical uses: Finance: Interest rates: 5% APR = 0.05 for calculations. Mortgage: 4.5% = 0.045. Credit card: 18% = 0.18 annual, 0.18/12 = 0.015 monthly. Investment returns: 7% = 0.07 gain multiplier. Shopping: Discounts: 30% off. Pay = price × (1 - 0.30) = price × 0.70. Sales tax: 8% = multiply by 1.08. Tip: 20% tip = bill × 0.20. Science/Stats: Probability: 75% chance = 0.75. Concentration: 5% solution = 0.05. Education: Test scores: 85% = 0.85 correct. GPA: Sometimes on 4.0 scale. Business: Profit margin: 25% = 0.25. Commission: 6% = 0.06 of sale. Market share: 15% = 0.15 of market.
How do I handle very small percentages as decimals?
Small percentage conversions: Less than 1%: 0.5% = 0.005. 0.1% = 0.001. 0.01% = 0.0001. Method: Divide by 100, count decimal places carefully. Examples: Interest rates: 0.25% = 0.0025 (savings rates). Chemical concentration: 0.05% = 0.0005 (pharmaceuticals). Error rates: 0.1% defects = 0.001 (1 in 1000). Scientific: Parts per million (ppm): 1 ppm = 0.0001% = 0.000001. Parts per billion (ppb): 1 ppb = 0.0000001%. Common errors: Forgetting leading zeros. 0.5% ≠ 0.5 (that's 50%). 0.5% = 0.005. Check: Multiply back. 0.005 × 100 = 0.5%. Precision: Use scientific notation for very small: 0.001% = 1×10⁻⁵.