Seafarer tools
Sea Time Calculator
Accurate sea time calculation for seafarers. Add one or more vessels with sign-on and sign-off dates to get months, days, and total sea days instantly.
Enter vessel sea service
Sign-on and sign-off days are not counted. Months use a 30-day sea-service month.
Results
Total Sea Time Across All Vessels
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Note: Under exclusive counting, same-day or consecutive calendar dates produce 0 sea days because sign-on and sign-off are not counted.
How counting works
Sea service days use exclusive sign-on/sign-off dates and fixed 30-day months.
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Sign-on and sign-off dates are excluded from the count (exclusive). Example: 01/07/2026–05/07/2026 = 3 sea days.
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Months use a fixed 30-day sea-service month (e.g. 95 days = 3 months, 5 days).
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Multiple vessels are added together (simple sum). Overlapping periods are not merged.