How to Calculate Demurrage (with a Worked Example)

Demurrage is the agreed sum payable when a vessel is detained beyond the laytime allowed for loading or discharging. The arithmetic is simple; the disputes come from how laytime is counted.

The formula

Demurrage = (Time used − Laytime allowed) × Demurrage rate. Laytime allowed comes from the cargo quantity and the agreed loading/discharging rate; time used is counted from the statement of facts, subject to exceptions such as weather and shifting.

Worked example

• Cargo 60,000 MT, discharge rate 10,000 MT/day → laytime allowed 6 days.
• Time actually used (per SOF, after exceptions): 8 days.
• Demurrage rate USD 18,000/day → (8 − 6) × 18,000 = USD 36,000.

The number is only as good as the laytime count behind it. NAVGreen reconstructs the laytime timeline from a verifiable record, so weather exceptions and pumping stoppages are defensible rather than disputed.