Demurrage Calculator
Demurrage from laytime used and daily rate.
About this calculator
Demurrage and despatch are the two sides of a charter party's laytime clause: demurrage is the penalty a charterer owes for taking longer than the allowed hours to load or discharge cargo, and despatch is the reward — usually half the demurrage rate — for finishing early. This calculator compares laytime allowed against laytime actually used; if used time exceeds the allowance, the excess hours (converted to days by dividing by 24) get multiplied by the daily demurrage rate. If time was saved instead, the spare hours get multiplied by the despatch rate, which is derived by applying the despatch percentage (typically 50%) to the demurrage rate.
Because a voyage either runs over or finishes early, not both, only one of demurrage charge or despatch credit will actually be nonzero for a given calculation, and the net charge line simply nets them against each other. Beyond the headline dollar figure, the calculator also converts the result into a per-ton cost and compares your actual loading/discharge rate (cargo tonnage divided by hours used) against the required rate needed to stay within the allowed laytime — a useful diagnostic for terminal operators trying to identify where a bottleneck cost money. The most common real-world complication this simple math doesn't capture: charter parties routinely carve out "laytime exceptions" for weather, strikes, or port congestion that stop the clock, so always check the actual charter party terms before treating a calculated demurrage figure as the final settled amount.
Legal Disclaimer
This calculator provides general estimates only and does not constitute legal advice. Laws, regulations, and court procedures vary significantly by jurisdiction. Consult a licensed attorney in your area for advice specific to your situation.
Inputs
Results
Demurrage Charge ($)
$25,000.00
≈ 13 gaming PCs
Net Charge ($)
$25,000.00
≈ 13 gaming PCs
How to Use This Calculator
- Enter Laytime Allowed in hours per the charter party agreement.
- Set Laytime Used — actual hours from NOR (Notice of Readiness) tender to completion of loading/discharge.
- Enter Demurrage Rate per Day and Despatch Rate % (typically 50% of demurrage).
- Enter Cargo Tonnage in metric tons.
- Review Demurrage Charge if laytime is exceeded or Despatch Credit if completed early.
- Check your charter party for any exceptions to laytime (weather, strikes, port congestion) before disputing demurrage.
How the result changes with Laytime Used (hours)
| Laytime Used (hours) | Demurrage Charge ($) | Net Charge ($) |
|---|---|---|
| 48 | $0.00 | -$12,500.00 |
| 72 | $0.00 | $0.00 |
| 144 | $75,000.00 | $75,000.00 |
| 240 | $175,000.00 | $175,000.00 |
What each input means
- Laytime Allowed (hours)
- Contractual laytime for loading/unloading.
- Laytime Used (hours)
- Actual time taken for cargo operations.
- Demurrage Rate ($/day)
- Daily demurrage rate per charter party.
- Despatch Rate (% of demurrage)
- Credit rate for early completion. Typically 50%.
- Cargo Tonnage (MT)
- Total cargo in metric tons.
What each result means
- Demurrage Charge ($)
- Charge for exceeding allowed laytime.
- Despatch Credit ($)
- Credit for finishing early.
- Net Charge ($)
- Demurrage minus despatch credit.
- Excess Days
- Days over allowed laytime.
- Days Saved
- Days under allowed laytime.
- Cost per Ton ($)
- Net charge per ton of cargo.
- Actual Rate (T/hr)
- Actual loading/unloading rate.
- Required Rate (T/hr)
- Rate needed to avoid demurrage.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersLaytime Allowed (hours) = 72, Laytime Used (hours) = 96, Demurrage Rate ($/day) = 25000, Despatch Rate (% of demurrage) = 50 = 5 input(s) provided
- Calculate Demurrage ChargeDemurrage Charge = excessDays * demurrageRatePerDay25000 = $25,000
- Calculate Net ChargeNet Charge = demurrageCharge - despatchCredit25000 = $25,000
- Calculate Despatch CreditDespatch Credit = earlyDays * despatchRate0 = $0
- Calculate Excess DaysExcess Days = excessHrs / 241 = 1
Engine last updated . Checked against 3 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why do I only ever get a demurrage charge or a despatch credit, never both?
The calculator compares Laytime Used against Laytime Allowed and computes only one gap: excess hours if you ran over, or spare hours if you finished early. A single voyage can't do both at once, so exactly one of excessHrs or earlyHrs will be zero, which is why only one of Demurrage Charge or Despatch Credit ever comes out nonzero — the Net Charge line just reflects whichever one applied.
Why is Despatch Credit usually about half the Demurrage Charge for the same number of hours?
Despatch Rate (% of demurrage) defaults to 50%, meaning the despatch rate applied per day is half the demurrage rate. So if you finish exactly as many hours early as another voyage ran late, the despatch credit for those hours comes out to roughly half the demurrage charge for the same hours — reflecting the common charter-party convention that rewarding early completion costs the charterer less than penalizing lateness.
What do the Actual Rate and Required Rate outputs tell me?
Required Rate divides your cargo tonnage by the hours you were allowed, showing the loading/discharge speed needed to finish exactly on time. Actual Rate divides the same tonnage by the hours you actually used. If Actual Rate is lower than Required Rate, that gap is the direct cause of your demurrage charge — it's a quick way to see whether a slow load rate, not just bad luck, drove the result.
Does this calculator account for laytime exceptions like weather or strikes?
No. It simply treats every hour between NOR tender and completion as counting toward Laytime Used. Real charter parties routinely include exceptions that stop the laytime clock for events like bad weather, strikes, or port congestion, which can significantly shrink the excess hours that actually count toward demurrage. Check the charter party's exceptions clause before treating this calculator's demurrage figure as the final settled amount.
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