Percentage Points vs Percent Change in Academic Writing

Percentage points measure the absolute gap between two percentages; percent change measures that gap relative to the starting percentage. If a pass rate rises from 40% to 50%, it rises by 10 percentage points but by 25%. In academic writing, use percentage points when you subtract two rates, and use percent change when you divide the change by the original rate. This guide is for students writing reports, essays, dissertations, and lab assignments who need to calculate and describe changes accurately.

The distinction matters because both answers can be mathematically correct while communicating different things. A reader who sees “a 10% increase” may understand a much smaller change than the one your data show. The method below gives you a repeatable calculation, sentence templates, worked examples, and a final accuracy check.

The Short Answer: Percentage Points vs Percent Change

A percentage-point change is the arithmetic difference between two percentages. A percent change is the difference divided by the original percentage, multiplied by 100. Purdue University’s style guidance uses the example of a rise from 10% to 13%: that is 3 percentage points and a 30% increase.

💡 Decision rule: If your calculation is new percentage minus old percentage, write “percentage points.” If you divide that difference by the old percentage, write “percent change.”

• Percentage-point change = new percentage − old percentage.
• Percent change = (new percentage − old percentage) ÷ old percentage × 100.
• Always identify the old value before calculating percent change because it is the denominator.

These measures answer different questions. Percentage points answer, “How far apart are the rates on a 0-to-100 scale?” Percent change answers, “How large is the change compared with where the rate started?” Neither measure is automatically better. Your research question determines which one belongs in the sentence.

Why the Two Measures Produce Different Numbers

Suppose a course completion rate moves from 20% to 30%. Subtraction gives a 10-percentage-point increase. Relative to the original 20%, however, the 10-point gain is half of the starting rate: 10 ÷ 20 × 100 = 50%. The absolute gap is 10 percentage points; the relative increase is 50%.

This wording follows the distinction summarized by The Journalist’s Resource at Harvard Kennedy School: use percent for change in relation to a previous number and percentage points for the difference between percentages. That source also stresses that confusion is common, which is why showing the start and end values is useful.

The starting value controls the relative result. A two-point rise from 4% to 6% is a 50% increase, while a two-point rise from 40% to 42% is only a 5% increase. The same percentage-point movement can therefore imply very different relative changes. Reporting the baseline prevents a technically correct figure from becoming misleading.

A Three-Step Method for Any Assignment

Step 1: Confirm that both values are percentages

Percentage points compare percentages or rates expressed on the same scale. You may compare a 2025 response rate of 62% with a 2026 response rate of 68%. You should not subtract a percentage from a raw count, such as comparing 62% with 68 respondents. First convert comparable quantities to the same unit.

Step 2: Calculate the absolute gap

Subtract the old percentage from the new percentage. Preserve the sign: a positive result is an increase, and a negative result is a decrease. If participation moves from 75% to 69%, then 69 − 75 = −6, so participation decreased by 6 percentage points. You can write “a decrease of 6 percentage points” rather than carrying the minus sign into prose.

Step 3: Calculate the relative change only if it answers the question

Divide the absolute gap by the old percentage and multiply by 100. For the participation example, (69 − 75) ÷ 75 × 100 = −8%. Participation therefore decreased by 8% relative to its starting level. Report one measure when it directly answers the question; report both when readers benefit from seeing absolute and relative scale.

Worked Examples for Academic Writing

Example 1: Comparing pass rates

A department reports that the pass rate rose from 60% before a curriculum change to 69% afterward. The percentage-point change is 69 − 60 = 9 percentage points. The percent change is 9 ÷ 60 × 100 = 15%. A clear result sentence is: “The pass rate rose from 60% to 69%, an increase of 9 percentage points, or 15% relative to the original rate.”

That sentence states what was measured, supplies both endpoints, and labels each result. It does not prove that the curriculum change caused the improvement; the study design and analysis must support any causal claim.

Example 2: Describing a decline

Survey completion falls from 80% to 72%. The absolute difference is 72 − 80 = −8, so the rate fell by 8 percentage points. The relative change is −8 ÷ 80 × 100 = −10%, so the rate fell by 10% relative to baseline. Do not write “completion fell by 8%” because that would describe a decline from 80% to 73.6%, not to 72%.

Example 3: A small baseline

A rare response rises from 2% to 3%. The one-point movement looks small on the percentage scale, but it is a 50% relative increase because 1 ÷ 2 × 100 = 50%. This example shows why relative figures can look dramatic when the baseline is small. Give the original and new rates so the reader can judge practical importance.

Example 4: A coefficient expressed in probability

Imagine a model estimates that an intervention changes the predicted probability of submitting an assignment on time from 0.70 to 0.76. Converting those probabilities gives 70% and 76%, a difference of 6 percentage points. If you also want a relative comparison, 6 ÷ 70 × 100 is about 8.6%. Check the model documentation before interpreting a coefficient itself as a probability change; not every regression coefficient is on a probability scale.

How to Choose Which Measure to Report

Use percentage points when your emphasis is the direct gap between rates: turnout, prevalence, pass rates, survey shares, probabilities, or proportions. This is usually the cleanest measure when comparing groups or two time points on the same percentage scale.

Use percent change when your emphasis is growth or decline relative to a baseline. It is useful when comparing changes that begin at different levels, but it can exaggerate the apparent size of movement from a very small baseline. State the denominator and time period so the comparison is reproducible.

Official statistics show the distinction in practice. The U.S. Bureau of Economic Analysis explains contributions to GDP growth in percentage points while describing overall GDP movement as a percent increase. In one worked explanation, 2.2 percentage points of a 3.6% GDP increase came from consumer spending. The labels identify two different quantities rather than interchangeable wording.

• Report percentage points when the research question asks for the difference between two rates.
• Report percent change when the question asks how much a value grew or shrank relative to its baseline.
• Report both when the audience needs absolute scale and relative context.
• Report the start and end values whenever the baseline is small or the result could be misread.

Sentence Templates That Keep the Meaning Clear

A good quantitative sentence lets the reader reconstruct your calculation. It names the measure, direction, endpoints, comparison group or time period, and unit. Avoid leaving “increase” unattached to a baseline.

From [old rate] to [new rate], [outcome] increased or decreased by [difference] percentage points. Relative to [baseline or comparison], [outcome] increased or decreased by [percent change]%. [Outcome] changed from [old rate] to [new rate]—a [difference]-percentage-point change and a [percent change]% change relative to baseline.

For example: “The share of students using office hours rose from 24% in the first survey to 30% in the second, a gain of 6 percentage points and a 25% increase relative to the first survey.” If only one measure is relevant, remove the other rather than crowding the sentence.

Formatting conventions vary by discipline and style guide. The Massachusetts Institute of Technology writing guide recommends the % symbol in scientific and technical writing, except at the start of a sentence, while nontechnical guidance may prefer the word. Follow your department’s required style consistently.

Common Mistakes and Edge Cases

Calling a percentage-point gap a percent change

If a rate moves from 45% to 55%, the gap is 10 percentage points, but the relative change is about 22.2%. Labeling the movement “10%” confuses two calculations. The safest repair is to show the arithmetic beside your draft sentence, then match the unit to the operation.

Dividing by the new value

Percent change uses the original value as the denominator. A rise from 40% to 50% is calculated as 10 ÷ 40 × 100 = 25%. Dividing by 50 would answer a different question: the gap as a share of the new value. Mark “old” and “new” before entering numbers in a calculator.

Starting from zero

Ordinary percent change is undefined when the original value is zero because division by zero is not defined. If a rate moves from 0% to 5%, report a rise of 5 percentage points and provide the endpoints. Do not invent an infinite or 500% increase. Explain that no relative percent change can be calculated from a zero baseline.

Using percent difference instead of percent change

Percent difference is often used for two values when neither is a baseline; its denominator is commonly the average of the two values. Percent change is directional and uses the original value. Check the terminology expected in your discipline, because formulas may be defined differently in laboratory manuals or methods texts.

Rounding too early

Keep unrounded values through the calculation and round only the final result. If rates are already rounded in a published table, do not report a relative change with false precision. A result such as 8.5714% will usually be clearer as 8.6%, provided your course or journal does not specify another rule.

A Pre-Submission Accuracy Checklist

1. Identify the outcome, groups or time points, and the original value.
2. Confirm that the two percentages use the same denominator and definition.
3. Subtract old from new to obtain the signed percentage-point change.
4. If needed, divide that change by the old percentage and multiply by 100.
5. Label the result “percentage points” or “percent change” to match the calculation.
6. Write the start and end values in the sentence so readers can verify the scale.
7. Check the direction, rounding, time period, and whether the design supports causal language.

When your evidence comes from several lectures, articles, and datasets, keep one note for the definition, one for each worked calculation, and one for the final wording. Snitchnotes can turn those notes into short practice questions—for example, asking you to calculate both measures from a pair of rates—so you rehearse the distinction before submitting your assignment.

Frequently Asked Questions

What is the difference between percent and percentage points?

Percent describes a proportion or a change relative to a baseline. Percentage points describe the arithmetic difference between two percentages. A rise from 30% to 36% is 6 percentage points, while the relative percent increase is 20% because 6 divided by the original 30 equals 0.20.

When should I use percentage points in an essay?

Use percentage points when comparing two rates, proportions, probabilities, poll shares, or percentages on the same scale. State both endpoints and the direction of change. This wording is especially clear for comparisons across groups or years because readers can see the direct distance between the two rates.

Can I report both percentage points and percent change?

Yes. Reporting both can show absolute and relative magnitude, especially when the baseline is small. Write the endpoints first, then label each measure: “The rate rose from 8% to 12%, a gain of 4 percentage points and a 50% increase relative to baseline.” Avoid repeating both when one fully answers the research question.

How do I calculate percent change when the original value is zero?

You cannot calculate an ordinary percent change from a zero baseline because the formula requires division by the original value. Report the new and old values and their percentage-point difference instead. For a move from 0% to 7%, write that the rate increased by 7 percentage points.

Is a 100% increase the same as 100 percentage points?

No. A 100% increase means the original value doubled, so 20% would become 40%. An increase of 100 percentage points means adding 100 points to a percentage, such as moving from 0% to 100%. The size of a percent increase depends on its baseline; a point increase does not.

Conclusion

To distinguish percentage points from percent change in academic writing, inspect the calculation: subtraction produces percentage points; dividing that difference by the starting percentage produces percent change. Choose the measure that answers your research question, show the baseline, and label the unit precisely. Before submitting, use the seven-step checklist or turn your examples into Snitchnotes practice questions so the distinction becomes automatic rather than a last-minute correction.

Sources

1. The Journalist’s Resource, Harvard Kennedy School — Percent change versus percentage-point change
2. Purdue University Brand Studio — Writing and editing style tips for percent and percentage points
3. U.S. Bureau of Economic Analysis — Contributions to percent change in real GDP
4. Massachusetts Institute of Technology — Percent, per cent, and percentage usage guide
5. Reed College Quantitative Skills Center — Percent and percentage-point guidance