Percentage Calculator — Of, Change, Add or Subtract
Almost every percentage question is one of five shapes: a share of a number, a share of a total, a change between two figures, adding or taking off a percent, or working backwards. Pick the shape, type two numbers, and the answer plus the formula appears together.
| Percent | Value | Remaining |
|---|---|---|
| 1% | 25 | 2,475 |
| 5% | 125 | 2,375 |
| 10% | 250 | 2,250 |
| 15% | 375 | 2,125 |
| 20% | 500 | 2,000 |
| 25% | 625 | 1,875 |
| 30% | 750 | 1,750 |
| 50% | 1,250 | 1,250 |
| 75% | 1,875 | 625 |
| 90% | 2,250 | 250 |
X% of N = (X ÷ 100) × N. A as a share of B = (A ÷ B) × 100. Percentage change = ((new − old) ÷ |old|) × 100, using the absolute value of the old number so a fall below zero still reads correctly. Add or subtract X% = N × (1 ± X ÷ 100), which is the one-step way to apply a discount or a tax. Reverse: if P is Y% of the unknown, the unknown = (P × 100) ÷ Y.
- Choose the question — X% of a number, A is what percent of B, percentage increase or decrease, add or subtract a percentage, or X is Y% of what number.
- Type two values — Both fields take decimals and commas, so 1,250.50 works. Labels change to match the mode you picked so you cannot enter the numbers the wrong way round.
- Read the answer and the working — The big number is the result; the panels under it show the raw change, the amount saved or added, and what is left over — the figures you actually have to write on a form or a receipt.
- Use the quick table — One percent through ninety percent of your number, with the remaining amount beside each, so a 12% or 17% figure is easy to estimate without re-entering anything.
- Percentage change divides by the absolute value of the old number, so a drop into negative territory still reads correctly instead of flipping sign.
- The add-and-subtract mode doubles as a discount and tax tool: it shows the amount saved, the price you pay, and the same number with 17% GST added.
- Reverse percentages are the one people get wrong — if 500 is 20% of something, the whole is 2,500, not 500 ÷ 0.2 written the other way.
- Everything is arithmetic on your device; no numbers are sent anywhere.
Percentage Calculator — questions
How do I calculate a percentage discount quickly?
Use Add or subtract %. Enter the percentage and the original price, and the tool returns both the price with it added and the price with it removed, plus the amount involved. A 20% coupon on Rs 5,000 saves Rs 1,000 and you pay Rs 4,000.
What is the difference between percentage change and percentage-point change?
If a rate moves from 10% to 12%, that is a 2 percentage-point rise but a 20% increase relative to where it started, because 2 is a fifth of 10. This tool reports the relative change, which is what most comparisons mean; say "percentage points" when you mean the straight subtraction.
How do I add GST or sales tax to a bill?
Multiply the amount by 1.17 for 17% tax, which is the same as add %. So Rs 2,500 with 17% becomes Rs 2,925, of which Rs 425 is tax. If the bill already includes tax and you want the pre-tax figure, divide by 1.17 instead — that is the reverse-percent mode.
Why does dividing by the old value use its absolute value?
Because percentage change should measure how far you moved from the starting point regardless of direction. If a stock goes from −50 to −20, dividing by −50 would report a positive-looking change for what is actually a worsening; taking the magnitude keeps the sign honest.
Can I use this for exam marks and percentages of total?
Yes — that is "A is what % of B". Score 34 out of 200 and it reports 17%. For a weighted aggregate, repeat per subject and add the marks themselves, not the percentages, because 90% of 200 marks is not the same as 90% of 50 marks.
How do percentages work for Zakat and salary raises?
Zakat is a straight 2.5% of qualifying wealth, so use X% of a number with 2.5 — or the dedicated Zakat calculator, which also checks the gold and silver nisab for you. A raise from Rs 60,000 to Rs 75,000 is a 25% increase, which the percentage-change mode shows along with the raw difference.