Allocate a full amount in proportion to the time or quantity used. This can help check a simple partial subscription, shared charge or proportional budget.
Prorated amount = full amount × quantity used / total quantity.
A 60-unit monthly charge for 10 of 30 days is 60 × 10 / 30 = 20. For a 31-day billing month, the same 10 days gives approximately 19.35.
Use the denominator specified by the contract. Actual days, a fixed 30-day month and hourly billing can produce different results. This proportional calculation does not interpret employment law, cancellation clauses or minimum charges.
Editorial responsibility: Nicolas Belotti · Methods and testing · Report an error
English edition: 16 September 2026.