ShipCalculators.com

Maritime reference · 3,066 calculators

Regulation-referenced calculators for people who run ships.

ShipCalculators.com is a free reference of maritime calculators, each traced to the IMO resolution, EU regulation, or class rule it implements. Every calculator shows the formula it applies and cites the exact MEPC resolution, EU article, or class circular.

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live calculators
1,390
Code lookup cards
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The six domains on the drawing above. Each card lists the calculators most often opened in that area.

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Featured calculator

Attained Carbon Intensity Indicator under MARPOL Annex VI Reg.28, calculation method per MEPC.336(76).

CII Attained Calculator

MEPC.336(76)Reg.28
Annual CO2 from BDNs and Cf
38,420t
Deadweight (capacity)
82,000t
Distance sailed, DCS
45,000nm
10.41g CO2 per dwt nm attained
C2026 rating

Worked example. Required CII uses Z = 11% for 2026 under MEPC.338(76); rating boundaries per MEPC.339(76).

What changes next

Dated instruments, each linked to the calculator that produces the number due.

30 Sep2026

EU ETS surrender

100% of 2026 emissions, up from 70% for 2025, under Directive (EU) 2023/959.

EUA liability →

31 Mar2027

IMO DCS and EU MRV reports

Fuel consumption data for 2026 under MARPOL Annex VI Reg.27 and the MRV Regulation.

IMO DCS annual →

31 May2027

DCS Statement of Compliance

Attained CII and the 2026 rating letter against the MEPC.339(76) boundaries.

CII rating →

1 Jan2030

FuelEU intensity step

GHG intensity 6% below 91.16 gCO2e/MJ under Regulation (EU) 2023/1805.

FuelEU GHG intensity →

Recently updated

Calculator pages by their last content change.

PageChanged
CII Year-on-Year Improvement Calculator
Measure year-on-year change in a ship's attained CII and see why a flat attained value …
CII Corrective Trajectory Projector
Project a ship's attained CII forward under an assumed improvement, against the tightening …
CII Corrective Plan Projector: D or E to C
Project the annual attained-CII reduction a ship needs to climb from D or E back to at …
CII Attained Calculator: Carbon Intensity Indicator
Compute a ship's attained CII from a year's fuel and distance, with the required CII and A …
Reversible Laytime Calculator: Multi-Port Pooling
Pool laytime across any number of load and discharge ports under reversibility: total used …

How every calculator is built and checked

Methodology →

Traced to the instrument

Each page names the governing regulation with its resolution number and shows the equation it applies with a symbol legend.

Reproducible by hand

Every calculator carries a worked example a reader can repeat on paper, and where the regulator publishes one, the tool reproduces the regulator's own figure.

Dated, not stamped

A page changes its updated date only when its content changes. The list below is drawn from the build's own history.

Most citedMARPOL Annex VIMEPC.336(76)MEPC.328(76)MEPC.364(79)SOLAS II-2IMSBC CodeIMDG CodeReg. (EU) 2023/1805IS Code 2008