The Secret to Calculating Takt Time in Your Head, Fast

People are always amazed when I do takt time calculations lickety-split in my head. Here’s my secret: it’s the result of a lot of practice with doing math in the head, and memorizing a few nifty net available time numbers. This formula:
Takt time = Net available time per shift / customer demand per shift
is simple division.
The denominator of customer demand per shift is a given based on a number you will derive either from a monthly or weekly average, or true orders that must ship each day. Unless you commit the sin of overproduction, or foolishly choose not to deliver what your customer will buy, the customer demand number is set for you, by your customer (or by planning).
The numerator of net available time per shift is the fun number, and the first part of the secret to calculating takt time in your head, fast. Memorize these useful numbers:
3,600: the number of seconds in one hour
27,000: the seconds in a 7.5 hour shift (8.5 hours 1 hour of breaks)
28,800: the seconds in a 8.0 hour shift (9 hours minus 1 hour of breaks)
30,600: the seconds in a 8.5 hour shift (10 hours minus 1.5 hour of breaks)
37,800: the seconds in a 10.5 hour shift (12 hours minus 1.5 hour of breaks)
These are the net available times you will most frequently encounter when doing takt time calculation. Simply divide the appropriate one of these by the customer demand number, and voila, you have takt time.
The second part of the secret to calculating takt time in your head, fast, is years of being drilled in multiplication and division tables in Japanese elementary schools, decades before they introduced “education with breathing room”. Practice may not make perfect, but it makes proficient.

3 Comments

  1. Kevin Young

    October 10, 2007 - 6:48 pm

    I need help. I work at Whirlpool where we are all about trying to be lean. I am helping design a line that is continuously moving and we are all in disagreement to how fast the line should move. Right now the Takt time is 120 seconds. If the line moves through each work cell and 120 seconds and there is a problem and the line stops we will never make our rate of 225. I do not think with the amount of small parts and having every thing built right on the moving line that we will be able to run at 100% efficiency. Is there any sort of guideline for a continuous moving line or anywhere I could find some other information about setting this line up.
    Thanks,
    Kevin Young

  2. dua'a

    November 8, 2007 - 12:37 am

    How to calculate the takt time

  3. Jon Miller

    November 8, 2007 - 8:45 am

    Takt time = net available time per working shift / customer demand per working shift
    Net available time = total working time per shift – (break times + lunch time + other planned down time)