Prorata Calculator

It calculates how much leave entitlement an employee has earned when they work only part of the accrual period — because they joined or left during the year. Enter the full entitlement for the whole period, the accrual period, the employment start or end date, a proration method and a rounding rule. You get the prorated entitlement, and Show details reveals the exact formula behind it.

Full entitlement × eligible units ÷ units in the accrual period. For a new hire, the eligible period runs from the employment start date to the end of the accrual period; for a leaving employee, from the start of the accrual period to their last eligible day. Both dates count. Take 24 days of annual entitlement, a calendar-year accrual period and a hire date of 15 March: the eligible period is 292 of 365 calendar days, so 24 × 292 ÷ 365 = 19.2 days.

Calendar days is the most precise — it counts every day of the eligible period. Full calendar months counts only months the employee is eligible for from the first to the last day, which gives the lowest result. Partial calendar months counts every month touched, even by one day, which gives the highest. The same 15 March new hire with 24 days gets 19.2 days by calendar days, 18 days by full calendar months and 20 days by partial calendar months. Pick the method your leave policy or local law prescribes.

Yes. Switch the entitlement unit to hours and enter the full entitlement in hours — the maths is identical and the result is returned in hours. This is the usual choice for part-time employees and for teams whose leave balances are kept in hours.

Yes. Set the accrual period to Other and pick any start and end date — for example 1 April to 31 March, or a fixed-term contract that runs for five months. The proration is calculated against the period you define, not against a fixed twelve months.

Four options: no rounding, round to the nearest whole unit, always round up to a whole unit, and round to the nearest half. Rounding up is the safe choice where a policy or local law requires you to resolve fractions in the employee's favour. Whichever you pick, the unrounded result stays visible under Show details, so you can always see what the rounding changed.

The calculator does the arithmetic — it does not interpret regulations. Many countries and internal policies prescribe a specific proration method and a specific rounding direction, and some require the entitlement to be credited monthly rather than as one prorated figure. Choose the options that match your policy, and confirm the outcome with whoever owns leave compliance in your organisation.

Yes — that is what the Time Off module does. Entitlement rules are configured once per contract type or policy, and Calamari accrues balances for new hires, prorates them for leavers, carries the remainder into the next year and keeps every balance up to date without a spreadsheet. This calculator is the manual version of one of those rules.