EEDI Calculator

Ship type

Capacity label

Use the capacity metric relevant to your vessel class.

Capacity (t)

Reference speed Vref (knots)

Auxiliary power PAE (kW)

Auxiliary SFC (g/kWh)

Auxiliary fuel

Auxiliary CF (tCO2/tFuel)

You may override the default fuel carbon factor.

Main engines Add one or more rows. Shares auto-normalize.

#	Power (kW)	SFC (g/kWh)	Fuel	CF (tCO2/tFuel)	Power share
1

Correction factors Use 1.00 if not applicable.

f_w (weather)

f_i (innovations / ice)

f_c (capacity)

f_l (limitations)

f_other (combined)

Tip

If engine shares do not sum to 1, they are normalized automatically.

Results appear above after submission.

Example data table

Ship type	Capacity (t)	Vref (kn)	Main engine P (kW)	Main SFC (g/kWh)	Fuel	Aux P (kW)
Bulk carrier	80,000	14.0	9,500	170	HFO	1,500
Container ship	120,000	20.0	33,000	165	MDO	4,000
General cargo	15,000	13.5	6,200	185	LFO	900

These examples are illustrative. Use verified design values for compliance reporting.

Formula used

This calculator uses a unit-consistent EEDI form:

EEDI = ( Σ(P_ME·share·SFC·CF) + P_AE·SFC_AE·CF_AE )
/ ( Capacity · V_ref ) · f_total

P in kW, SFC in g/kWh, Vref in knots (nm/h).
CF is fuel carbon factor (tCO2/tFuel).
Capacity is the chosen capacity metric (often DWT).
f_total is the product of correction factors used.

How to use this calculator

Enter capacity and reference speed from your design basis.
Add one or more main engines with power and SFC.
Select fuels or enter custom carbon factors.
Enter auxiliary power and SFC for electrical loads.
Apply correction factors only when justified.
Click Calculate, then export CSV/PDF for records.

Notes and engineering guidance

Interpretation

Lower EEDI values indicate better CO2 efficiency per transport work. Use consistent capacity definitions across comparisons.

Compliance reporting

This tool supports design-stage screening. For formal compliance, confirm all terms and factors against applicable IMO guidance and class rules.

Design drivers of EEDI results

EEDI is most sensitive to transport work assumptions and fuel emission factors. In typical design studies, a 10% speed change can shift the index by roughly 9–11% when power and factors stay fixed. Use the graph to check whether your result is driven by numerator terms or denominator assumptions.

Fuel carbon factor selection

Carbon factor (CF) converts fuel consumption to CO2. Conventional liquid fuels often cluster around CF≈3.11–3.21 tCO2/tFuel, while LNG can be lower on a tank‑to‑wake basis. If you swap fuel but keep SFC and power unchanged, the numerator scales almost linearly with CF. Record the CF source and keep units consistent to avoid hidden conversion errors.

Main engine efficiency inputs

Main engine power and SFC dominate the numerator. As an engineering rule, improving SFC by 5 g/kWh at constant power reduces the main‑engine CO2 term by about (Power·5·CF) gCO2/h. For a 10,000 kW plant with CF=3.114, that is ~155,700 gCO2/h. If you model two engines, allocate realistic operating shares (for example 0.60/0.40) to reflect the design point.

Auxiliary load management

Hotel loads, cargo systems, and electrical margins can raise auxiliary power. If PAE increases from 1,500 kW to 2,000 kW with SFC 215 g/kWh and CF 3.206, the auxiliary term rises by about 344,645 gCO2/h. Because auxiliaries are often less sensitive to speed than propulsion, they can dominate at lower Vref. Consider waste‑heat recovery, variable‑speed drives, and tighter margins for continuous services.

Correction factors and documentation

Correction factors should be applied only when supported by guidance and design evidence. Keeping f_total close to 1.00 improves transparency and reduces review friction. When factors are needed, document the rationale, source, and the exact values used so reviewers can reproduce the calculation. As a practical check, report both the base EEDI (before factors) and the adjusted EEDI used for decisions. Always keep calculation inputs traceable for future internal verification audits.

Using exports for audit trails

CSV exports support quick benchmarking across iterations, while the PDF snapshot preserves a human‑readable record. Use consistent naming conventions, store input sets with revision notes, and link results to the design case that produced the speed, capacity, and power values. Exporting after each design review creates a lightweight audit trail.

FAQs

1) What capacity should I enter?

Use the capacity metric required for your vessel category, commonly DWT for cargo ships. Keep the same definition across comparisons so EEDI changes reflect design improvements, not input shifts.

2) Why does speed affect EEDI so strongly?

Speed appears in the denominator as transport work. With numerator held constant, increasing speed reduces EEDI, and decreasing speed increases it. Real designs also change power with speed, so use a consistent design point.

3) Can I model multiple main engines?

Yes. Add rows for each engine and set a power share for the operating condition. If shares do not sum to 1.00, the calculator normalizes them to maintain consistent weighting.

4) When should I override a carbon factor?

Override CF only when you have a verified factor for the fuel and reporting basis. Mixing sources can distort comparisons. Keep documentation of the value, units, and reference used.

5) What does the correction factor block represent?

It combines optional multipliers that adjust the base index for recognized conditions. If you do not have a justified factor, leave it at 1.00. The total multiplier is shown as f_total.

6) Are the CSV and PDF suitable for compliance submission?

They are suitable for internal records and traceability. For formal submissions, confirm that all terms match your applicable rules and that supporting evidence is retained alongside the exported outputs.