Edit: This is related to a production process where a max value cannot be exceeded, and cannot be less than the minimum. There is then an 'optimal' value, which is a term suggested in the comments by John Lawler

For example, if the upper/lower limits are 3.5 and 3.0, the ideal middle value would be 3.25.

Is there a term for this 'middle value'?

  • For some reason the word 'nominal' came to my head but that appears to be wrong.
    – pay
    Sep 13, 2016 at 20:14
  • 2
    That's the arithmetic mean (a + z) / 2, and with only two values it's also the median. If there's no other reason for its idealness, you can call it either one. If there are other reasons, you could refer to it as optimum or optimax, depending. Sep 13, 2016 at 20:21
  • 1
    Yes it is not simply a mean, it is related to a production process where there is an upper and lower limit, and an 'optimum' value as you have stated.
    – pay
    Sep 13, 2016 at 20:21
  • 2
    @pay nominal is correct in certain contexts. If I need to drill a pilot hole 0.202 +/- 0.001 inches, 0.202 is the nominal dimension.
    – Phil Sweet
    Sep 13, 2016 at 20:51
  • @PhilSweet Oh thanks for that, so I'm not completely crazy! This does refer to a measurement of an object that is quite small (the end of a wire, sort of). Do you think that would still apply?
    – pay
    Sep 13, 2016 at 20:52

5 Answers 5


How about target value?

Aimed-for output from a process, or result from a measurement.

This has the advantage of not necessarily being the arithmetic mean or median, but rather an identified "number to shoot for". In some processes there might be more tolerance below the target than above or vice versa.

  • This is the answer (IMHO).
    – Drew
    Sep 13, 2016 at 20:48
  • I'll likely use 'target value', 'optimal', or 'nominal', thanks.
    – pay
    Sep 14, 2016 at 12:34

In some profession and skills, such as metalworking and engineering, the word "tolerance" is used for the minimum and maximum values when those values are stated with respect to the desired defined value. For example, a particular dimension may be given as .250 investment with a tolerance of .0005 inches, so that the minimum value is .2495 inches, and the maximum value is .2505 inches. In such places, .250 would be the "specified value".

This is often stated as,".250 plus or minus .0005 inches", and in writing, the "plus or minus" is often replaced with a character created with a plus sign and a minus sign in the same space, with the hype of the minus sign below the.plus sign.

  • This is a possible option as well. I could switch the format slightly to having the focus be primarily on the optimal value with an upper and lower tolerance range.
    – pay
    Sep 13, 2016 at 20:53

Consider rated value.

For example:

  • Deviations of the mains voltage from the rated value must not exceed the tolerance limits given in the specifications.
  • To obtain increased capacity and efficiency, the screw compressor is operated at a speed greater than its rated speed.

It's the midpoint of your target range or interval or optimal range or whatever.


How about the sweet spot?

From The Free Dictionary:

sweet spot: an area or range that is most effective or beneficial: an engine's sweet spot of rpm's for maximum fuel-efficiency; a store's demographic sweet spot of women in their twenties.

With regard to your example: For a given function f(X), the value of X between the minimum and maximum values of X at which f(X) is optimal is the sweet spot. The sweet spot is not necessarily the arithmetic average, the geometric mean, or any other fixed function of the maximum and minimum values of X.

Sweet spot is perhaps most easily understood in terms of the following definition:

The place on a bat, club, racket, or paddle where it is most effective to hit a ball. [The Free Dictionary]

The optimum place is clearly somewhere between the two ends of the bat, club, racket, or paddle, and the location of that place is the sweet spot. The exact location, which could be determined experimentally, will vary depending on the design of the bat, club, racket, or paddle.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.