Last updated October 23, 2026.
Which one do you need?
If the job is a general percent, use the percentage calculator. If you have an original price and a percent off, use discount. If you have a cost and a selling price, use profit margin. If pay is sales times one rate, use commission. If you are splitting a bill plus a tip, use the tip calculator. Each page stops at a different result.
Side by side
| Tool | Use when | Not for | Published example |
|---|---|---|---|
| Percentage Calculator | You need a general percent: part of a whole, what percent, or a percent change. | A sale price, a margin, a commission check, or a tip split each has its own page. | 15% of 80 is 12. |
| Discount Calculator | You know the original price and the percent off, and you want the sale price. | It does not compute profit margin or markup. Use profit margin when you have cost and selling price. | 80 with 25% off has 20 saved and a sale price of 60. |
| Profit Margin Calculator | You know cost and selling price and want profit, margin percent, and markup percent. | A shelf discount is not a margin. A sales commission is not a markup. | Cost 40 and price 60 produce a profit of 20, a margin of 33.33%, and a markup of 50%. |
| Commission Calculator | Pay is a sales total times one flat rate, with an optional base. | It does not handle tiers, margin, or a restaurant tip. | 2,000 in sales at 8% plus a 500 base pays 160 in commission and 660 total. |
| Tip Calculator | You want a tip, a bill total, and each person’s share. | It is not a discount, a tax, or a sales commission. | A 64 bill at 18% for 4 people has an 11.52 tip, a 75.52 total, and 18.88 each. |
Method and assumptions
Percentage has four modes: X% of Y, what percent A is of B, increase, and decrease. Discount subtracts a percent from an original price. Margin is profit ÷ selling price. Markup is profit ÷ cost. Commission is sales × rate, plus optional base pay. Tip is bill × tip percent, then divided by the party size.
The same numbers, different questions
Start with 80. Fifteen percent of 80 is 12 on the percentage calculator. That is a part of a whole. It is not a sale price. The discount example takes the same 80 and applies 25% off: you save 20 and the sale price is 60. Those are different percents on purpose. A 25% discount is not a 25% margin, and 15% of 80 is not the amount you save in the discount example.
Margin starts from cost and price, not from a percent-off. Cost 40 and price 60 produce a profit of 20, a margin of 33.33% (profit divided by the selling price), and a markup of 50% (profit divided by the cost). The sale price of 60 showed up in the discount example too, but the discount page never saw the cost of 40. That is why the percents are not interchangeable. Commission is another stop: 2,000 in sales at 8% plus a 500 base is 160 of commission and 660 total. It does not know the cost of the goods.
The tip example is a 64 bill at 18% for 4 people: tip 11.52, total 75.52, and 18.88 each. Eighteen percent of 64 is the tip, which the percentage page could also compute as a part of a whole, but it will not divide by the party size or add the tip back onto the bill. Use the page that names the leftover step you still need.
Common mistakes
- Quoting markup and margin as if they were the same percent. The denominators differ: cost versus selling price.
- Stacking a second discount on the sale price and calling it the same as one larger discount off the original. This discount page applies one rate to the original price.
- Using the commission page for tiered pay. It is one flat rate plus an optional base.
- Using the tip page for sales tax. Tax is a separate calculator. The tip page does not know a tax rate.
Percentage Calculator
You need a general percent: part of a whole, what percent, or a percent change.
A sale price, a margin, a commission check, or a tip split each has its own page.
Example. 15% of 80 is 12.
Discount Calculator
You know the original price and the percent off, and you want the sale price.
It does not compute profit margin or markup. Use profit margin when you have cost and selling price.
Example. 80 with 25% off has 20 saved and a sale price of 60.
Profit Margin Calculator
You know cost and selling price and want profit, margin percent, and markup percent.
A shelf discount is not a margin. A sales commission is not a markup.
Example. Cost 40 and price 60 produce a profit of 20, a margin of 33.33%, and a markup of 50%.
Commission Calculator
Pay is a sales total times one flat rate, with an optional base.
It does not handle tiers, margin, or a restaurant tip.
Example. 2,000 in sales at 8% plus a 500 base pays 160 in commission and 660 total.
Tip Calculator
You want a tip, a bill total, and each person’s share.
It is not a discount, a tax, or a sales commission.
Example. A 64 bill at 18% for 4 people has an 11.52 tip, a 75.52 total, and 18.88 each.
Sources and limits
- Disclaimer — Everyday arithmetic. Not payroll, tax, or pricing advice.
Questions
Why is margin lower than markup on the same product?
Margin divides profit by the selling price. Markup divides the same profit by the cost. The denominators differ, so the percents differ.
Is a 25% discount the same as a 25% margin?
No. A discount reduces the original price. A margin is profit divided by the price you sell at.