Frequently asked questions
Quick answers to the questions people ask when using percentage calculations.
Is 100% the maximum?
No. 150% of 200 is 300. Percentages over 100% are normal when a part exceeds its chosen reference value.
Can percentage change be negative?
Yes. A drop from 100 to 80 is −20%. The minus sign communicates the direction of change.
Why is a 50% loss followed by a 50% gain not break-even?
Starting with 100, a 50% loss leaves 50. A 50% gain on 50 adds 25, ending at 75. Returning from 50 to 100 requires a 100% increase.
Why is percent change from zero undefined?
Percent change uses the starting value in the denominator. Dividing by zero is undefined, so use an absolute change or another meaningful comparison instead.
What is the difference between margin and markup?
Margin divides profit by selling price; markup divides profit by cost. Both are useful but they are not interchangeable.
Do you store my calculations?
The calculators run in your browser and do not submit entered numbers to our server. Third-party advertising providers may process browsing information according to their policies; see our Privacy Policy.
Are the tax calculations exact?
No. Sales-tax bases, exemptions, rounding and jurisdictions differ. This calculator provides an estimate for a single stated rate.
How do I calculate an original price after a discount?
Divide the sale price by 1 minus the discount percentage as a decimal. For $60 after 25% off, $60 ÷ 0.75 = $80.
Why can rounding cause differences?
Rounding each step separately versus rounding the final answer can change the displayed cents. Verify important totals against your provider’s calculation method.