How to use the percentage calculator
- Value and Percentage: enter a number and a rate to get that percentage of the number — for example 2500 and 18 to find the GST on a ₹2,500 invoice.
- Old value and New value: enter a before and after figure to get the percentage change. A negative result means a decrease.
- Value is % of new: this third result divides the Value field by the New value field. To find what percentage 45 is of 250, put 45 in Value and 250 in New value.
- Results update as you type. Percentage change shows a dash when the old value is zero, because growth from zero cannot be expressed as a percentage.
The three percentage formulas, worked through
1. Percentage of a number
Result = value × percentage ÷ 100. A Noida consultancy invoices ₹2,500 plus 18% GST: 2,500 × 18 ÷ 100 = ₹450, so the invoice total is ₹2,950.
2. Percentage change
Change = (new − old) ÷ old × 100. Monthly enquiries rose from 200 to 250: (250 − 200) ÷ 200 × 100 = +25%. If they fall back from 250 to 200, the change is (200 − 250) ÷ 250 × 100 = −20%, not −25%, because the starting point is now larger. A rise and an equal fall are never the same percentage.
3. What percentage one number is of another
Share = part ÷ whole × 100. If 45 of your 250 leads were qualified, enter 45 as Value and 250 as New value: 45 ÷ 250 × 100 = 18%. The same method gives click-through rate (clicks ÷ impressions), a channel's share of budget or the conversion rate between two funnel stages — the lead funnel calculator does that for a whole funnel at once.
Quick reference: everyday percentage questions
All rows are worked examples calculated with the formulas above.
| Question | Calculation | Answer |
|---|---|---|
| 18% GST on ₹1,200 | 1,200 × 18 ÷ 100 | ₹216 |
| GST inside a ₹1,180 price that includes 18% | 1,180 − (1,180 ÷ 1.18) | ₹180 |
| 20% Diwali discount on ₹3,499 | 3,499 × 20 ÷ 100 | ₹699.80 off |
| Original price if ₹2,800 is after 20% off | 2,800 ÷ (1 − 0.20) | ₹3,500 |
| Ad spend up from ₹40,000 to ₹52,000 | (52,000 − 40,000) ÷ 40,000 × 100 | +30% |
| CTR with 1,250 clicks on 50,000 impressions | 1,250 ÷ 50,000 × 100 | 2.5% |
| Salary from ₹6,00,000 to ₹6,60,000 | (6,60,000 − 6,00,000) ÷ 6,00,000 × 100 | +10% |
Common percentage mistakes and how to avoid them
- Removing GST by subtracting 18%. 18% of ₹1,180 is ₹212.40, but the GST inside ₹1,180 is only ₹180. Divide by 1.18 to get the pre-tax price, then subtract.
- Reversing a discount by adding the same percentage. ₹2,800 plus 20% is ₹3,360, not the original ₹3,500. Divide by (1 − discount) instead.
- Confusing percent with percentage points. A conversion rate moving from 2% to 3% is a rise of 1 percentage point but a 50% increase. Say which one you mean in reports.
- Averaging percentages. A campaign converting 10% of 100 visitors and another converting 2% of 900 do not average 6%. Add the conversions (10 + 18 = 28) and divide by total visitors (1,000) for 2.8%.
- Treating margin and markup as one number. Profit as a percentage of price and as a percentage of cost differ; the profit margin calculator shows both.
Practical use cases
- Retail store owner: check that a "40% off" sticker on a ₹1,499 kurta really charges ₹899.40.
- Performance marketer: report month-on-month change in leads, CPL and spend in a monthly marketing dashboard.
- Freelancer: add 18% GST to a quote, or find the TDS share of a payment.
- Student or job seeker: compare a hike offer against the current CTC.
- Startup founder: express a proposed marketing budget as a share of monthly revenue before comparing it with the ranges in our guide to startup digital marketing cost in India.
Everything runs in your browser — nothing you type is sent to our servers.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For 18% of ₹2,500, that is 2,500 × 18 ÷ 100 = ₹450. In the calculator, enter 2500 in Value and 18 in Percentage and the result appears under "Percentage of value". The same method works for discounts, commissions and tax.
How is percentage change calculated?
Subtract the old value from the new value, divide by the old value and multiply by 100. Going from 200 to 250 is (250 − 200) ÷ 200 × 100 = 25%. A negative result means a decrease. If the old value is zero the change cannot be expressed as a percentage, so the tool shows a dash.
How do I find what percentage one number is of another?
Divide the part by the whole and multiply by 100. To find what share 45 is of 250, calculate 45 ÷ 250 × 100 = 18%. In this tool, enter the part in the Value field and the whole in the New value field, then read "Value is % of new". This is how click-through and conversion rates are calculated.
How do I remove 18% GST from a price that includes it?
Divide the GST-inclusive price by 1.18 to get the price before tax, then subtract that from the total to get the GST amount. For ₹1,180, the pre-tax price is ₹1,000 and the GST is ₹180. Subtracting 18% of ₹1,180 directly gives a wrong answer of ₹212.40.
Why is a 25% increase followed by a 25% decrease not back to the start?
Because each percentage is calculated on a different base. ₹200 up 25% is ₹250, but 25% of ₹250 is ₹62.50, so a 25% fall leaves ₹187.50. To return to ₹200 from ₹250 you need a 20% decrease. Always check which value the percentage is measured from.