Unit Converter

The units a deck officer actually reaches for — including the three different tons, the two different stowage factors, and the cargo intake they are looked up to answer.

Scratch working — nothing is saved

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And in everything else

    Stowage factor and density

    These two are reciprocals, not a scaled version of one another, so this crossing sits outside the tables above — a plain conversion factor would give a confidently wrong number.

    Cargo intake

    The question a stowage factor is looked up to answer. Broken stowage is part of that question — bagged and baled cargo loses a slice of the hold to gaps that a plain volume ÷ SF quietly ignores.

    The other way round. To find the volume a parcel needs, enter the tonnes below and the stowage factor above.
    Three things a plain factor table gets wrong
    Temperature carries an offset. Every other family here is a bare multiplication, but °C and °F do not share a zero. Each unit is held as base = value × factor + offset, and the offset is what stops °F being converted with a multiplier alone. You can see it in the working: 50 °F × 0.5555556 + (−17.777778) = 10 °C.
    Stowage factor is the reciprocal of density. SF (m³/t) = 1000 ÷ density (kg/m³). It is not a scaled version of density, so it cannot live in the same table — which is why that crossing has its own panel above. A non-positive input has no physical inverse, so it returns nothing rather than infinity.
    “Ton” is three different masses, and “ft³/ton” is two different stowage factors. A tonne is 1000 kg, a long ton 2240 lb, a short ton 2000 lb — and a stowage factor in cubic feet may be per tonne or per long ton. Every one of them is spelled out in the lists above and there is no bare “ton” to pick by mistake. Long against short is a live error in US grain ports.
    Commas and points both work. Type 12,5 or 12.5 — the same number either way. A field that cannot be read shows nothing rather than a zero.
    What this is. A converter. It does arithmetic on the numbers you type and shows its working so you can check it. It knows nothing about your ship, your cargo or your tables. Figures that matter — a stowage factor, a density, an intake — come from the shipper’s declaration, the cargo documents and your own stability book, and the Master remains responsible for every one of them.

    A web version of a tool from DeckWatch, the work planner for ship’s deck officers. Nothing here is approved, certified or class-accepted.