Between 10pm and 5am the hour lasts 52 minutes and 30 seconds and pays 20% more. See the full calculation, the extension rule and the effect on overtime and weekly rest.
Two advantages, not one
Urban night work runs from 10pm to 5am and has two distinct consequences: a 20% premium over the daytime hour (CLT, article 73) and the shortened night hour, which lasts 52 minutes and 30 seconds.
Confusing the two is the most common error. Paying only the 20% forgets that seven clock hours at night equal eight working hours, and applying only the reduction skips the premium.
Rural work has different rules: 9pm to 5am in crop farming, 8pm to 4am in livestock, with a 25% premium and no shortened hour.
The calculation, step by step
Take a R$ 3,000 salary on a 220-hour month: the normal hour is R$ 13.64. A shift from 10pm to 5am has 7 clock hours, which count as 8 night hours because of the reduction (7 divided by 52.5 minutes, multiplied by 60).
Those 8 night hours pay R$ 109.12 of normal salary plus 20%, R$ 21.82, totalling R$ 130.94 for the night. Twenty nights in a month add up to R$ 436.40 in night premium alone, before its effect on everything else.
Extension: what happens after 5am
When the shift is worked entirely within the night period and extends past 5am, the extended hours also carry the night premium (TST Precedent 60, item II).
The logic is continuity: someone who started at 10pm and left at 6am worked a night shift, and the last hour is no less demanding because the clock rolled over. A system that cuts the premium at 5am sharp is wrong by default.
Effect on overtime, weekly rest and everything else
As a habitual salary item, the night premium belongs in the overtime base: overtime on a night shift is calculated on the hour already increased by 20%, not on the plain daytime hour.
It also feeds paid weekly rest and the vacation and 13th-salary average, and it is part of the social-security, income-tax and FGTS bases. On termination it is part of the proportional items.
A mid-month shift change deserves attention: an employee leaving the night shift loses the premium from then on, but the shortened hour and the effects of the period already worked remain due.
Night premium calculated from the punch
In Avos the night premium comes from the timesheet: the system splits hours by band, applies the shortened hour, recognises the extension past 5am and carries the value into the overtime, weekly-rest, vacation and 13th-salary bases. The payslip shows night hours on their own line, which prevents the monthly question about where the number came from.