To decide when to use fewer and less in writing, decide if you are counting items or an amount. For example:
- There are fewer marbles in this jar than in that one (items).
- There is less water in this glass than in that one (an amount).
- She has less than $50 (an amount), but fewer than four $10 bills (a number).
Trust your ear: if you would use "much," (much more water) use "less"; if you would use "many," (many more marbles) use "fewer."
Use "less than" when describing a mass, a measurement, or a total, such as:
- The building was less than 50 years old, or less than 10 percent germinated.
In this case, "years" refers to a period of time, not individual years and a percentage is an amount.
To compare amounts or numbers, use more than, such as "she has more than 25 cats." "Over" describes a spatial relationship: the bird flew over the parking lot. "Over" also can describe the passage of time: over the past 15 years, they became friends.
For more information, please contact Mark Stadtlander at mark@ksu.edu.