Percentage calculator for finding X% of Y, X as a percent of Y, and the percentage increase or decrease from X to Y. Results update as you type.
The Tooloogle Percentage Calculator answers the three most common percentage questions in one place: "What is X% of Y?", "X is what percent of Y?", and "What is the percent increase or decrease from X to Y?". Enter your values to calculate discounts, tips, exam scores, salary changes, or sales tax. Read the result that answers your question.
Use "what is X% of Y" to apply a rate, "X is what % of Y" to compare a part with a whole, or percent change to compare an old value with a new one. The results also show how percentages relate: if A is 25% of B, then B is 400% of A, and going from A to B is a +300% change. Compare the results to check which base each calculation uses.
Three calculators in one view: (1) percentage-of-value, (2) ratio-as-percentage, (3) percent change: all visible at the same time.
Live updates: results refresh as you type in any field; no "Calculate" button.
Rounded results: results are rounded to two decimal places.
Increase or decrease: the percent-change result uses green for increases and red for decreases, with an "Increase" or "Decrease" label.
Decimal inputs: accepts decimals (e.g. 12.5%) for fractional rates.
Negative inputs: accepts negative values (e.g. profit moving from a loss into the black). Check the starting value when interpreting percent change.
What is X% of Y? Enter the percentage and the base value: the result shows what that percentage of the base equals (e.g. 15% of 200 = 30).
X is what % of Y? Enter X (the part) and Y (the whole): the result shows the part as a percentage of the whole (e.g. 30 is 15.00% of 200).
Percent change from X to Y? Enter the original value X and the new value Y: the result shows the percent increase (positive) or decrease (negative) from X to Y, with a clear color and label.
The same Value X and Value Y inputs feed both the "X is what % of Y" and "% change" calculators, so a single edit updates both.
Read whichever result answers your question; the others are for context.
Use the calculator for discount amounts ("30% off a price of 79.99 = how much?") and final prices, tips, or sales tax. For split bills, use the Tooloogle Tip Calculator. You can also work out exam scores as percentages ("I got 47 out of 60: what percentage is that?") or compare a salary change ("old salary 52,000, new salary 58,000: what's the percent increase?"). Other uses include portfolio returns, conversion rate changes, weight changes, commissions, and year-over-year revenue growth. Check the starting value when a headline quotes a "30% increase" without showing the math.
The calculator uses these three formulas:
1. Percentage of a value: result = (percentage / 100) × value. Example: 15% of 200 = (15 / 100) × 200 = 0.15 × 200 = 30. Use this when you know a percentage and want to apply it to a base: calculating discounts, tax, tips, commission.
2. Ratio expressed as a percentage: result = (X / Y) × 100. Example: 30 is what percent of 200? = (30 / 200) × 100 = 0.15 × 100 = 15%. Use this when you have two raw numbers and want to express their relationship as a percentage: exam scores out of total, conversion rates, market shares.
3. Percent change from X to Y: result = ((Y − X) / X) × 100. Example: change from 50 to 65 = ((65 − 50) / 50) × 100 = (15 / 50) × 100 = 30%. A positive result is an increase; a negative result is a decrease. Note: percent change is asymmetric: going from 50 to 100 is +100%, but going from 100 back to 50 is −50%, not −100%. The base for percent change is always the starting value.
Always be explicit about the base when reporting percent changes: "sales doubled" (a +100% increase) is much more readable than "sales rose 100%" (which some people instinctively read as "rose to 100%" or "became 100% larger"). For percentages above 100%, double-check your inputs: many real-world percentages cap at 100% (a discount above 100% would mean paying you to take the product), and a result above 100% often means the inputs are swapped. For very small percentages (below 1%), consider switching to basis points (1 basis point = 0.01%) for clarity, especially in finance contexts. When chaining percent changes, remember they don't add: a 10% increase followed by a 10% decrease leaves you at 99%, not 100%, of the original (because the decrease is applied to a now-larger base). For percent of a percent (e.g. "25% of the 30% who responded"), multiply: 25% × 30% = 7.5%.
Use the Tooloogle Discount Calculator for retail prices, the Tip Calculator for restaurant bills, or the Compound Interest Calculator for investment growth.
How to Use Percentage Calculator - Percent Of, Ratio and Change
Enter the percentage and base value in the X% of Y calculation. Read the resulting amount.
Enter the part as Value X and the whole as Value Y. Read the result for X as a percentage of Y.
Enter the original value as X and the new value as Y. Read the percent change and the increase or decrease label.
Percentage calculator for finding X% of Y, X as a percent of Y, and the percentage increase or decrease from X to Y. Results update as you type.
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Apr 30, 2026Type:
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