Shift diff is basically extra pay for working certain hours, like evenings, nights, or weekends, which are typically considered less desirable. It's a way for employers to compensate employees for the inconvenience of working these hours. The amount of shift diff varies, but it's usually a percentage of the employee's hourly wage, like 5-10% extra for evening shifts or 10-15% for night shifts. Some employers also offer a flat rate per hour or a lump sum for working certain shifts. The calculation is usually straightforward, just multiply the employee's hourly wage by the shift diff percentage, and that's the extra pay they'll get for working those hours.