HelloCalcSabaiTH

Percentage & Discount Calculator

Quick percentages: price after a 30% discount, stacked discounts like 50% + 20%, X as a percent of Y, percent change and the original price.

Price after discount

THB
%
%
Sale price
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You save
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X% of a number

%
Result
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X is what % of Y

Result
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Percent increase / decrease

Result
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Original price before discount

THB
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Original price
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How it works

This page has 5 percentage calculators. Fill in only the box you need and the answer appears instantly. Copy result includes every box you filled in, and the page link remembers your numbers.

Formula

Sale price = price × (1 − discount%) × (1 − extra discount%)

X% of Y = X ÷ 100 × Y

X as % of Y = X ÷ Y × 100

Percent change = (new − old) ÷ old × 100

Original price = sale price ÷ (1 − discount%)

What is a percentage?

Percent (%) means “per hundred”. 25% is 25 parts out of 100, or 0.25. Every percentage calculation comes from this one idea; the only difference is which numbers you know and which one you want.

Mental math shortcuts

  • 10% — move the decimal point one place left. 10% of 850 = 85
  • 5% — half of 10%. 5% of 850 = 42.50
  • 20% — 10% times 2. 20% of 850 = 170
  • 25% — divide by 4. 25% of 850 = 212.50
  • 50% — divide by 2
  • 1% — move the decimal point two places left

Sale prices at a glance

Price 10% off 20% off 30% off 50% off 70% off
199 179.10 159.20 139.30 99.50 59.70
590 531 472 413 295 177
1,290 1,161 1,032 903 645 387
2,990 2,691 2,392 2,093 1,495 897
5,900 5,310 4,720 4,130 2,950 1,770

Stacked discounts don’t simply add up

“50% off + extra 20% off” is not 70% off. The second discount applies to the reduced price:

  • 1,000 baht minus 50% is 500
  • 20% of 500 is 100, leaving 400
  • That is 600 baht off, or 60%

Formula: real discount = 1 − (1 − first discount) × (1 − second discount)

Up then down by the same percent doesn’t return to the start

A 100 baht share that rises 50% to 150 and then falls 50% ends at 75, not 100, because the second 50% is taken from a bigger base. Likewise, after a 50% fall you need a 100% gain to get back to where you started.

Everyday examples

  • Pay rise — 25,000 to 27,000 is an 8% raise
  • Profit — buy at 80, sell at 100: that is 25% markup on cost but a 20% margin on the selling price. Always say which base you mean.
  • Test score — 42 out of 60 is 70%
  • Original price — paid 1,050 baht after 30% off, so the original price was 1,050 ÷ 0.7 = 1,500 baht

FAQ

How do I work out 30% off?

Multiply the price by 0.7 (100% − 30%). For example, 1,500 baht with 30% off is 1,050 baht, saving 450 baht.

Is 50% + 20% off the same as 70% off?

No. The second discount applies to the already reduced price: 1,000 baht minus 50% is 500, minus another 20% is 400. That is 60% off in total, not 70%.

How do I calculate a percent increase?

(new − old) ÷ old × 100. A salary rising from 25,000 to 27,000 baht is an 8% increase.

How do I find the original price from the sale price?

Divide the sale price by (1 − discount). If you paid 800 baht at 20% off, the original price was 800 ÷ 0.8 = 1,000 baht.

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