Increase By vs Increase To: The Tiny Preposition That Changes the Math

A student was presenting a quarterly chart in a business English class. "Sales increased to twenty thousand dollars," she said proudly, "from twenty thousand to forty thousand." Her teacher paused, smiled, and asked, "So the new total is twenty thousand, or forty thousand?" The student froze. She had meant the gap was twenty thousand — but the word to had quietly told the room something completely different. One little preposition, and the math fell apart.

Why This Matters

You will hear increase by and increase to every time someone reads a chart, reports a salary bump, describes a price change, or talks about a rising temperature. The same words appear with rose, grew, climbed, dropped, fell, decreased, and declined. In a meeting, a wrong preposition can turn a small change into a huge one, or vice versa. On a writing task or a speaking exam, examiners listen for this distinction, because it tells them whether you can describe data accurately. The rule is short, but the consequences of getting it wrong are large.

If you have already read Percent, Percentage, and Percentage Points: Small Words, Big Mistakes, you have seen how a missing word can flip a number from a tiny shift into a giant one. The by vs to split works the same way, only with absolute amounts instead of rates.

The Pattern

Increase by describes the size of the change. It is the gap between the old value and the new value.

• Sales were one hundred. They increased by twenty. New total: one hundred and twenty.
• Her salary rose by ten percent. If she was earning fifty thousand, she now earns fifty-five thousand.
• The temperature dropped by five degrees overnight.

Increase to describes the new value itself. It tells you where the number ended up, not how big the jump was.

• Sales increased to one hundred and twenty. (We do not know the old number from this sentence alone.)
• Her salary rose to fifty-five thousand. (We know she now earns fifty-five.)
• The temperature dropped to five degrees. (It is now five degrees, no matter what it was before.)

The same logic applies to decrease, fall, drop, decline, shrink, rise, climb, and go up / down.

There is also a very useful third pattern: from X to Y. It names both endpoints in one breath.

• Sales rose from one hundred to one hundred and twenty.
• The rate dropped from eight percent to five percent.

When you use from … to …, you do not need by — the gap is already implied. Mixing by with from / to is the most common slip.

Wrong / Natural / Why

Common Situations

Reading a sales chart. "Revenue rose by about fifteen percent this quarter, from four million to roughly four point six million." Notice how rose by names the gap and from … to … names the endpoints. Pair them, and your sentence does double duty — it reports the size and the destination at the same time.

Salary talk. "I got a raise — my pay went up by eight percent." That tells your friend the size of the boost. If you say "my pay went up to eighty thousand," you are telling them the new figure. Both can be true at once, but they answer different questions.

Test score progress. A tutor says, "Your reading score improved by five points, from twenty-two to twenty-seven." If you only said "improved to twenty-seven," your study partner would not know how much progress you made. Both numbers together tell the full story.

Weather report. "Overnight, temperatures dropped to about three degrees Celsius, a fall of roughly seven degrees from yesterday's high." Notice the noun-form trick here: a fall of seven degrees uses of because fall is a noun, not a verb. As a verb, you would say "fell by seven degrees."

Currency and price changes. "The euro strengthened by two cents against the dollar, climbing to one point ten." Financial reporting almost always pairs the size of the move with the new level. Listen for the by … to … pattern next time you hear a market update.

Common Mistakes

• Using to when you mean the size of the change: "Sales increased to ten percent" when sales actually rose by ten percent of the previous total.
• Stacking by and to together: increased by to ten percent is never correct.
• Forgetting the from … to … structure exists. You can name both endpoints in one clean phrase.
• Using of with verbs of change. "Increased of ten percent" is wrong. Use by. With noun forms (an increase of ten percent), of is fine.
• Mixing percentage points and percent in the gap. If unemployment goes from four percent to six percent, it rose by two percentage points, not by two percent.
• Saying increased on or increased in by accident. In works for time spans ("in the third quarter"), not for the size of a change.
• Dropping the preposition altogether: "Sales increased ten percent" is acceptable in journalism, but in careful spoken English, "increased by ten percent" is clearer.

Mini Practice

Fill in the blank with by, to, or from / to — and check that the math actually works.

1. The number of users grew ______ five hundred ______ eight hundred this month.
2. Our delivery time dropped ______ thirty minutes; it used to be ninety, and now it is sixty.
3. The temperature climbed ______ thirty-five degrees Celsius by noon, the highest reading of the week.
4. Inflation rose ______ half a percentage point, from two percent ______ two point five percent.
5. The rent on this apartment went up ______ a hundred and fifty dollars this year.

Summary

Increase by is the size of the change. Increase to is where the number lands. From X to Y names both ends of the journey in one elegant phrase. Pick by when you mean the gap, to when you mean the new value, and from … to … when you want to tell the listener everything in one breath. Once this becomes automatic, your data sentences will stop fooling your audience — and stop costing you points on every test that asks you to describe a chart.

Want to practice numbers, quantifiers, and units in real test sentences? Start practicing on ExamRift.