direct-reading

adjective
  1. (of an instrument) calibrated so that a given quantity to be measured can be read directly off the scale without the need of a multiplying constant
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Examples from the Web for direct-reading

Historical Examples of direct-reading