The notions of fair measure and fair entropy were introduced by Misiurewicz and Rodrigues [13] recently, and discussed in detail for piecewise monotone interval maps. In particular, they showed that the fair entropy h(a) of the tent map fa, as a function of the parameter a = exp(htop(fa)), is continuous and strictly increasing on [ √ 2, 2]. In this short note, we extend the last result and characterize regularity of the function h precisely. We prove that h is 1 2 -Hölder continuous on [ √ 2, 2] and identify its best Hölder exponent on each subinterval of [ √ 2, 2]. On the other hand, parallel to a recent result on topological entropy of the quadratic family due to Dobbs and Mihalache [7], we give a formula of pointwise Hölder exponents of h at parameters chosen in an explicitly constructed set of full measure. This formula particularly implies that the derivative of h vanishes almost everywhere.