How to use the laytime calculator
- Set the laytime allowed. Either divide the cargo quantity by the agreed loading or discharging rate, or enter a fixed number of days from the charter party.
- Enter when laytime commenced and when operations were completed. Commencement normally follows the notice of readiness (NOR) plus any notice or turn time in the charter party.
- List the time that does not count, taken from the statement of facts: rain on a weather-working-day charter, Sundays and holidays under SHEX terms, shifting between berths, breakdowns of ship's gear and so on.
- Enter the demurrage rate. Despatch defaults to half demurrage, the usual term, but you can change it.
How laytime, demurrage and despatch are calculated
Both demurrage and despatch are pro rata: a day is 24 consecutive hours, so 20 hours is 0.8333 of a day.
Key terms
- Laytime: the time the charterer may use to load or discharge without paying extra, in addition to the freight.
- Demurrage: liquidated damages the charterer pays for each day, or part of a day, that the ship is kept beyond the laytime.
- Despatch: money the owner pays back for finishing early, usually at half the demurrage rate.
- SHINC / SHEX: Sundays and holidays included, or excluded, from laytime. Under SHEX "unless used", Sunday time counts if the ship actually worked.
- Weather working day (WWD): a working day that counts only if weather allows work; time lost to rain is excluded.
- Reversible laytime: one allowance for loading and discharging together, so time saved at one end can be used at the other.
Worked example
A bulk carrier loads 50,000 t at 10,000 t per day, so 5 days (120 hours) of laytime are allowed. Laytime commenced at 08:00 on Monday 2 November 2026 and loading was completed at 14:00 on Sunday 8 November: 6 days 6 hours, or 150 hours, of gross time. The statement of facts shows 6 hours of rain and 4 hours shifting berth, so 140 hours were used.
- Time on demurrage: 140 − 120 = 20 hours = 0.8333 days
- Demurrage at USD 15,000 per day: 0.8333 × 15,000 = USD 12,500
Had the charter party been SHEX, the 14 hours on Sunday 8 November would also not count (unless the terms say "unless used" and the ship worked). Only 6 hours would then be on demurrage, about USD 3,750. The wording of the charter party decides every one of these points, which is why most laytime disputes are about the exceptions rather than the arithmetic.
Avoiding laytime disputes
- Make sure the NOR is valid: the ship must be at the agreed place and actually ready in every respect.
- Have the master and agent sign a detailed statement of facts with start and end times for every stoppage.
- Record weather stoppages with times, and note whether cargo work actually stopped.
- Remember that once the ship is on demurrage, most exceptions stop applying.
SENA's chartering and brokering team negotiates laytime terms and checks laytime statements every day. Planning a voyage? Estimate the time at sea with the voyage ETA calculator.