Omikuji Tools Life & Calc

Ratio & Percentage Calculator

Simplify ratios, split totals by ratio, percent of / percent change and proportions (a:b = c:x), calculated as you type.

✨ Features

  • Simplifies ratios, including decimals (1.5:2.5 → 3:5), and shows each part's share of the total
  • Splits money or quantities by ratio; whole-unit rounding distributes remainders so the total always matches
  • Four percentage calculators: percent of, P% of, percent change, and value after a change
  • Solves x in a:b = c:x; everything updates as you type; copy or share a URL

🪄 Use cases

Splitting costs or rewards

Divide a purchase by contribution ratio, to the unit.

Mixing and dilution

Concentrate:water = 1:9 for 500 mL.

Year-over-year figures

80 → 100 is +25%, 100 → 80 is −20%.

Scaling recipes

3 eggs for 2 people – how many for 5?

🔒 Privacy

Input is processed in your browser and never sent to a server. Only when you shorten a share URL is that URL (including the input) sent to the shortening service.

❓ FAQ

What does simplifying a ratio mean?

Dividing every term by their greatest common divisor: 12:18:30 ÷ 6 = 2:3:5. Decimals are scaled to whole numbers first.

How are rounding remainders handled?

With whole-unit rounding, each share is floored and the leftover units go one at a time to the shares with the largest fractional parts (largest remainder method), so the total is preserved.

Do +25% and −25% cancel out?

No. 80 + 25% = 100, but 100 − 25% = 75. Going from 100 back to 80 is −20%.

How does the proportion work?

For a:b = c:x, x = b × c ÷ a. "2 items cost 300, 5 items?" gives a=2, b=300, c=5, x=750.

🔗 Related tools

Fraction Calculator Probability Calculator Prime Factorization & Divisors Unit Converter & Calculator Bill Splitter Price Calculator Compound Interest Calculator Dice Roller

Simplify a ratio

Split a total by ratio

％ Percentages

What percent is A of B?
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What is P% of B?
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Percent change from A to B
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A changed by P%
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Proportion a : b = c : x

"2 items cost 300, what do 5 cost?" → a=2, b=300, c=5

x
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