Nephelometric measuring devices are described. The nephelometric measuring devices can be configured such that an amount of scattered light having different pathlengths impingent upon one or more scattered-light detectors from a beam propagating through a suspension can result in substantially equivalent sensitivity and in correlation between the scattered-light detectors' response and a turbidity value of the suspension. The response of the scattered-light detector(s) receiving scattered light at a nephelometric angle of 85-110° from a beam of light propagating through the suspension can be in accordance to an equation selected from a group of non-linear equations where: x/y=anxn+an−1xn−1+ . . . +a2x2+a1x+a0; where “n” is an integer greater than 0; “x” is equal to the turbidity value of the suspension; “y” is equal to the response of the scattered-light detector; and “an” are calibration coefficients. The maximum response of the scattered-light detector occurs at a turbidity value dependent upon the effective scattered-light pathlength.