reduce by

reduce (something) by (something)

To make something smaller, weaker, narrower, etc., by some amount, degree, or margin. The government has reduced our budget by nearly 25%. Even reducing the temperature on the thermostat by a few degrees could save you hundreds on your energy bill each month.
See also: by, reduce
Farlex Dictionary of Idioms.

reduce something by something

to diminish something by a certain amount. I have to reduce your allowance by two dollars per week until you pay me back for the broken window. I will reduce the bill by a few dollars.
See also: by, reduce
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • reduce (something) by (something)
  • (Someone or something) called, they want their (something) back!
  • be (one's) man/woman
  • taper off
  • be more/bigger/greater than the sum of its parts
  • be greater/more than the sum of its parts
  • tomorrow
  • add fuel to the fire/flames, to
  • be in step (with someone or something)
  • be in a world of (one's) own
References in periodicals archive
For the red wine reduction: In a large saucepan, combine red wine and shallots; reduce by three quarters.
For the truffle emulsion: In a saute pan, bring stock to boil and reduce by half.
"This is as panicked as I get!" Alessandro Stratta