Reference Chart · Maritime
Metric units in the maritime sector
Units, symbols and conversions, arranged by quantity. Each dial shows an animated instrument of the quantity it measures.
Motion active · respects the reduced-motion settingGeneral metric (SI) units
Length
Distance & measure
| kilometre | km | 1 km = 1000 m |
| metre | m | SI base unit |
| centimetre | cm | 0.01 m |
| millimetre | mm | 0.001 m |
| micrometre | µm | 10⁻⁶ m |
| nanometre | nm | 10⁻⁹ m |
Area
Surface
| square kilometre | km² | |
| square metre | m² | |
| square centimetre | cm² | |
| square millimetre | mm² | |
| hectare | ha | 100 are = 10,000 m² |
| are | a | 100 m² |
| centiare | ca | 1 m² |
Volume
Capacity
| cubic metre | m³ | |
| cubic decimetre | dm³ | = 1 l |
| cubic centimetre | cm³ | = 1 ml |
| cubic millimetre | mm³ | |
| hectolitre | hl | 100 l |
| litre | l | 1 dm³ = 0.001 m³ |
| millilitre | ml | = 1 cm³ |
Mass
Weight
| tonne | t | 1000 kg |
| kilogram | kg | SI base unit |
| gram | g | 0.001 kg |
| milligram | mg | 10⁻⁶ kg |
| microgram | µg | 10⁻⁹ kg |
Force
Newton
| newton | N | 1 N = 1 kg·m·s⁻² |
| kilonewton | kN | 1000 N |
Moment
Torque
| newton metre | N·m | moment of a force |
Pressure
Force per area
| megapascal | MPa | 10⁶ Pa = 1 N/mm² |
| pascal | Pa | 1 Pa = 1 N/m² |
| newton / m² | N/m² | = 1 Pa |
| newton / mm² | N/mm² | = 1 MPa |
| bar | bar | 10⁵ Pa = 100 kPa |
| millibar | mbar | 1 hPa = 100 Pa |
| microbar | µbar | 0.1 Pa |
Temperature
Thermometer
| kelvin | K | SI base unit |
| degree Celsius | °C | °C = K − 273.15 |
Work & energy
Joule
| megajoule | MJ | 10⁶ J |
| joule | J | SI unit |
| newton metre | N·m | = 1 J |
| watt-second | Ws | = 1 J |
| kilowatt-hour | kWh | 3.6 × 10⁶ J |
| electronvolt | eV | 1.602 × 10⁻¹⁹ J |
Power
Watt
| megawatt | MW | 10⁶ W |
| kilowatt | kW | 1000 W |
| watt | W | 1 W = 1 J/s |
Time
Duration
| nanosecond | ns | 10⁻⁹ s |
| microsecond | µs | 10⁻⁶ s |
| millisecond | ms | 0.001 s |
| second | s | SI base unit |
| minute | min | 60 s |
| hour | h | 60 min |
| day | d | 24 h |
Angle
Direction
| radian | rad | SI unit |
| degree | ° | 1° = (π/180) rad |
| arcminute | ′ | 1° = 60′ |
| arcsecond | ″ | 1′ = 60″ |
| gradian (gon) | gon | 1 gon = (π/200) rad |
| steradian | sr | solid angle |
SI prefixes
Orders of magnitude
| giga | G | 10⁹ |
| mega | M | 10⁶ |
| kilo | k | 10³ |
| hecto | h | 10² |
| deca | da | 10¹ |
| deci | d | 10⁻¹ |
| centi | c | 10⁻² |
| milli | m | 10⁻³ |
| micro | µ | 10⁻⁶ |
| nano | n | 10⁻⁹ |
Maritime-specific units
Distance at sea
Navigation
| nautical mile (int.) | M / NM | 1852 m |
| cable length | — | 1/10 nautical mile = 185.2 m |
| fathom | fm | 6 feet = 1.8288 m · depth |
| foot | ft | 0.3048 m (non-metric) |
Speed
Way
| knot | kn | 1 nautical mile/hour = 1.852 km/h ≈ 0.514 m/s |
Tonnage & cargo
Capacity
| gross tonnage | GT | total enclosed volume |
| net tonnage | NT | usable cargo volume |
| deadweight | DWT | in tonnes |
| displacement | Δ | in tonnes |
| container measure | TEU | 1 × 20-foot container |
Ship dimensions
Hull sizes
| length overall | LOA | in m |
| beam (moulded) | B | in m |
| draught | T (d) | in m |
| depth | D | in m |
| freeboard | — | in m |
Towing force
Bollard pull
| bollard pull | BP | in tonne-force (tf) or kN |
| kilonewton | kN | 1000 N |
Air pressure · meteo
Barometer
| hectopascal | hPa | 1 hPa = 1 mbar = 100 Pa · weather reports |
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