Gross Profit Margin Trend Calculator

How it is calculated

The tool compares two gross margins you have already worked out, one for the earlier period and one for the later. Enter each as a percentage (42 means 42%), calculated as gross profit ÷ revenue × 100. It reports the change in percentage points, current − previous, and the relative change, (current − previous) ÷ |previous| × 100, and echoes the previous margin. The previous margin cannot be 0, because a relative change from zero is undefined. A margin above 100% is impossible, since gross profit cannot exceed revenue, so a previous or current margin above 100 shows no result. A margin can be negative if cost of sales exceeded revenue, and the relative change is measured against the absolute size of the previous margin, so a rise from −20% to 10% reads as +150%. The tool does not take revenue or cost figures.

Common mistakes

• Entering profit or revenue amounts instead of margins. The fields take percentages; compute gross profit ÷ revenue for each period first.
• Confusing points with percent. A move from 42% to 45.5% is 3.5 percentage points, but 8.33% in relative terms, and the two should not be quoted interchangeably.
• Entering the margin as a decimal such as 0.42. Enter 42; a value of 0.42 is read as 0.42% and the point change shrinks accordingly.
• Comparing periods with different cost definitions, for example one with freight in cost of sales and one without. The trend then reflects the accounting, not the business.
• Entering a margin above 100%, for example a markup figure like 130. Gross margin cannot exceed 100% of revenue, so the tool shows no result; convert a markup into a margin first.