About ShipCalc

ShipCalc is an independent, free website with calculators for people who work in shipping: chartering, operations, technical management and compliance. It is not affiliated with the IMO, the European Commission or any shipping company. Every calculation runs in your browser; nothing you type is sent anywhere.

What it calculates

Sea distances between 132 major ports (500 route pages so far), with sailing times and a route map. Distances are estimates from a model of the main shipping lanes, not a navigational product.
CII rating: attained and required Carbon Intensity Indicator and the A–E rating under MARPOL Annex VI for 13 ship types, 2023–2030.
EU ETS: emissions in scope, EU allowances to surrender and their cost, 2024–2030, plus 94 route pages.

Data sources

Ports and distances

Port positions: World Port Index (NGA Pub. 150), US National Geospatial-Intelligence Agency.
Port codes and names: UN/LOCODE, UNECE. Older industry codes that UN/LOCODE now gives to airports (e.g. CNSHA) are shown alongside.
Port selection: Lloyd's List One Hundred Container Ports 2025 (top 50); the largest port of each coastal EU/EEA country by goods handled in 2024 (Eurostat transport statistics, maritime datasets mar_go_am_*); the ports at each end of the Suez and Panama canals; the largest iron ore, coal and crude oil export ports; and the three largest bunkering ports.
Sea routes: searoute (Python), built on the Eurostat SeaRoute / MARNET maritime network.
Accuracy check: 30 routes compared with NGA Pub. 151 Distances Between Ports (2001). The median difference is 1.4%; long routes come out 0.5–2% longer, short coastal routes can be further off.
Maps: coastlines from Natural Earth (public domain), drawn with Leaflet.

CII

IMO resolutions (Marine Environment Protection Committee):

MEPC.352(78): how to calculate the attained CII (G1)
MEPC.353(78): reference lines (G2)
MEPC.338(76) and MEPC.400(83): reduction factors 2023–2030 (G3)
MEPC.354(78): rating boundaries (G4)
MEPC.364(79): fuel carbon factors

EU ETS

EU legislation from EUR-Lex:

Directive (EU) 2023/959, amending the ETS Directive 2003/87/EC: coverage, phase-in, ice-class rule
Regulation (EU) 2015/757 (EU MRV) and Delegated Regulation (EU) 2023/2776: emission factors
Delegated Regulation (EU) 2020/1044: global warming potentials of CH₄ and N₂O
Implementing Regulation (EU) 2023/2297: neighbouring container transshipment ports
EUA price: 84.46 €/t on 2026-10-06, from EU Carbon (EUA) settlement price, Purely Energy EU ETS price page. Updated by hand; you can enter your own price.

Checks and updates

Each calculator is tested against worked examples: the examples in the IMO guidelines where they exist, otherwise cases worked out by hand. Every regulatory value is traced to the resolution or article it comes from, and the pages are reviewed when the rules change.

Disclaimer

Disclaimer. Distances are estimates computed with the open-source searoute model on a simplified sea network. Actual routes depend on traffic separation schemes, draft, weather and canal transits; our estimates are typically within 1–3% of NGA Pub. 151 on long routes and can be further off on short ones. CII results use the IMO guidelines cited on this page without the correction factors and voyage adjustments of MEPC.355(78). The official rating is issued after IMO DCS verification by the flag Administration or recognized organization. EU ETS results use the default emission factors of the EU MRV Regulation for fossil fuels and leave out biofuels and e-fuels, the derogations for outermost regions, small islands and public service contracts, and the rules for offshore ships and ships below 5,000 GT. The allowance price is a snapshot, not a quote. Surrender obligations are based on verified emissions reported under EU MRV. ShipCalc results are for planning and information only. They are not navigational, commercial, legal or regulatory advice. Always verify against official sources before making decisions.