Percentage Calculator

Calculate percentages three ways — what is X% of Y, X is what % of Y, and X is Y% of what.

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Find a Percentage of a Number, What Percent X Is of Y, or the Whole From a Part

What is X% of Y?X is what % of Y?X is Y% of what?

Percentage (%)

Value

Part

Whole

Part

Percentage (%)

Decimals: use a period or a comma — 99.5 or 99,5.

—Result

About the Percentage Calculator

This percentage calculator solves the three most common percentage questions in one tool. Pick a mode — "What is X% of Y?", "X is what % of Y?", or "X is Y% of what?" — enter your numbers, and the answer appears instantly. Results update live as you type, so there's nothing to submit.

Every calculation shows the formula it used, making it easy to double-check the math or explain it to someone else. The calculator accepts both US-style decimals (99.5) and European-style commas (99,5), so it works regardless of your locale.

Three percentage formulas, one tool

Every percentage problem boils down to one of three unknowns. This calculator labels them as three modes so you never have to rearrange the formula yourself.

Mode 1 — "What is X% of Y?"
  result = Y × (X / 100)
  Example: 15% of 200 = 200 × 0.15 = 30

Mode 2 — "X is what % of Y?"
  result = (X / Y) × 100
  Example: 30 is what % of 200 = (30 / 200) × 100 = 15%

Mode 3 — "X is Y% of what?"
  result = X / (Y / 100)
  Example: 30 is 15% of what = 30 / 0.15 = 200

The three standard percentage formulas.

Percentage formulas in Excel, Google Sheets, and SQL

You can replicate any of the three modes directly in a spreadsheet cell or a SQL query.

Excel / Google Sheets (A2 = percent, B2 = value):
Mode 1: =B2*A2/100
Mode 2: =A2/B2*100        (A2 = part, B2 = whole)
Mode 3: =A2/(B2/100)      (A2 = part, B2 = percent)

Spreadsheet formulas — adjust cell references to match your layout.

-- SQL: all three modes as computed columns
SELECT
  value * (pct / 100.0)        AS mode1_result,
  (part / NULLIF(whole, 0)) * 100 AS mode2_pct,
  part / NULLIF(pct / 100.0, 0)   AS mode3_whole
FROM my_table;

SQL — NULLIF guards against division by zero.

FAQ

How do I calculate what 15% of 200 is?

Select mode 1 ("What is X% of Y?"), enter 15 as the percent and 200 as the value. The calculator multiplies 200 × 0.15 = 30. The formula is shown below the result.

How do I find what percentage 30 is of 200?

Select mode 2 ("X is what % of Y?"), enter 30 as the part and 200 as the whole. The calculator divides 30 ÷ 200 × 100 = 15%. This is the standard "part over whole" formula.

Is this calculator accurate for very large or very small numbers?

Yes. It uses JavaScript's native floating-point arithmetic and displays up to 6 significant decimal places. For extremely precise financial work, a dedicated decimal-arithmetic tool may be more appropriate.