Under Zambian law, gratuity is calculated as a percentage of your basic pay earned during your employment period. [Employment Code Act, S.73(1)] requires your employer to pay you gratuity at a rate of not less than 25 percent of the basic pay you earned during the contract period when your long-term contract ends.
If your employment contract is terminated before the full contract period is complete, you are entitled to gratuity calculated on a pro-rata basis according to how long you actually worked [Employment Code Act, S.73(2)]. This means the gratuity amount is reduced proportionally to match the period of employment you completed.
The calculation is straightforward: take your total basic salary earned during employment, multiply it by at least 25 percent, and that is your minimum gratuity entitlement. Your employer may pay more than this minimum, but cannot pay less. For terminated contracts, the same percentage applies, but only to the basic pay corresponding to the actual time worked.