How To Calculate Gross Tonnage

Gross Tonnage Formula:

\[ GT = V \times (0.2 + 0.02 \times \log_{10}(V)) \]

Gross Tonnage (GT):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Gross Tonnage?

Gross Tonnage (GT) is a dimensionless index calculated from the total enclosed volume of a vessel. It represents the overall size of a ship and is used for regulations, safety rules, and registration fees rather than actual weight.

2. How Does the Calculator Work?

The calculator uses the Gross Tonnage formula:

\[ GT = V \times (0.2 + 0.02 \times \log_{10}(V)) \]

Where:

\( GT \) — Gross Tonnage
\( V \) — Total enclosed volume in cubic meters (m³)
\( \log_{10} \) — Base-10 logarithm

Explanation: The formula calculates a vessel's gross tonnage based on its total enclosed volume, with a logarithmic component that accounts for the non-linear relationship between volume and tonnage measurement.

3. Importance of Gross Tonnage Calculation

Details: Gross Tonnage is crucial for determining port dues, safety regulations, manning requirements, and vessel registration. It serves as a key measurement in maritime law and international shipping conventions.

4. Using the Calculator

Tips: Enter the total enclosed volume of the vessel in cubic meters. The volume must be a positive value greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between gross tonnage and deadweight tonnage?
A: Gross tonnage measures the total enclosed volume of a vessel, while deadweight tonnage measures the weight a vessel can carry including cargo, fuel, and supplies.

Q2: Is gross tonnage the same as displacement?
A: No, displacement refers to the actual weight of water displaced by a vessel, while gross tonnage is a volumetric measurement of enclosed spaces.

Q3: Why use a logarithmic function in the calculation?
A: The logarithmic component accounts for the fact that larger vessels have relatively less tonnage per unit volume than smaller vessels, reflecting operational efficiency differences.

Q4: What are typical gross tonnage values for different vessel types?
A: Small boats: 1-100 GT, fishing vessels: 100-500 GT, cargo ships: 1,000-50,000 GT, large container ships: 50,000-200,000+ GT.

Q5: How is enclosed volume measured for tonnage calculation?
A: Enclosed volume includes all spaces below the main deck and enclosed spaces above the main deck, measured according to specific international tonnage measurement conventions.