# What is the denominator in calculating daily range as a percentage?

Assume a stock had an open of \$100 and a close of \$102. If the high of the day was \$103 and the low was \$99, the daily range is obviously \$4. What is the best way to express the daily range in terms of percentage? If you take the range and divide it by the open, you get 4.00%. If you take the high and divide it by the low you get 4.04%. The first method seems more intuitive but the second method is more computationally efficient and may be good enough. Is there an industry standard for this calculation? • why is it more computationally efficient? – SRKX Oct 13, 2011 at 5:56 • Because in the first case you have to subtract then divide. In the second you only have to divide. Oct 13, 2011 at 7:18 • ah ok. but that's$O(1)\$. not sure I really see the point.
– SRKX
Oct 13, 2011 at 7:39
• SRKX: The second method divides two numbers that are directly calculated. The first method takes those same numbers and adds a third number for which care must be taken that it is the correct one. The open 12-days ago, for an n=12 calculation, can be confused with 11 or 13 and then the calculation would be wrong. The second method adds complexity that is prone to OBO error. Oct 13, 2011 at 10:36