1. A method for producing an R-T-B based sintered magnet comprising:a step of preparing an R-T-B based sintered magnet material, which is represented by the following formula (1):

uRwBxGayCuzAlqM(100-u-w-x-y-z-q)T (1)

where

R is composed of light rare-earth element(s) RL and a heavy rare-earth element(s) RH, RL is Nd and/or Pr, RH is at least one of Dy, Tb, Gd and Ho, T is a transition metal element and includes Fe, M is Nb and/or Zr, and u, w, x, y, z, q, and 100-u-w-x-y-z-q are expressed in terms of % by mass;

the RH accounts for 5% by mass or less of the R-T-B based sintered magnet, the following inequality expressions (2) to (5) and (12) being satisfied:

0.20?x?0.70 (2)

0.07?y?0.2 (3)

0.05?z?0.5 (4)

0?q?0.1 (5)

0.844?w ?0.93 (13)

v=u?(6?+10?+8?), where the amount of oxygen (% by mass) of the R-T-B based sintered magnet is ?, the amount of nitrogen (% by mass) is ?, and the amount of carbon (% by mass) is ?;

when 0.40?x?0.70, v and w satisfy the following inequality expressions (6) and (7):

50w?18.5?v?50w?14 (6)

?12.5w+38.75?v??62.5w+86.125 (7)

and, when 0.20?x?0.40, v and w satisfy the following inequality expressions (8) and (9), and x satisfies the following inequality expression (10):

50w?18.5?v?50w?15.5 (8)

?12.5w+39.125?v??62.5w+86.125 (9)

?(62.5w+v?81.625)/15+0.5x?x ?(62.5w+v?81.625)/15+0.8 (10).

wherein in the step of preparing the R-T-B based sintered magnet material , R-T-B based sintered magnet material is obtained by sintering;

a high-temperature heat treatment step of heating the R-T-B based sintered magnet material to a temperature of 730° C. or higher and 1,020° C. or lower, and then cooling to 300° C. at a cooling rate of 25° C./min or more; and

a low-temperature heat treatment step of heating the R-T-B based sintered magnet material, after the high-temperature heat treatment step, to a temperature of 440° C. or higher and 550° C. or lower;

wherein Hcj of the R-T-B based sintered magnet satisfies the following expression:

Hcj (kA/m) ?1,360 +160 [Dy]+240[Tb], where the amount of Dy (% by mass) is [Dy]) and the amount of Tb (% by mass) is [Tb]).