Tonne is unfortunately overloaded, the US and the UK have their own versions, but for the rest of the world is on metric, and a tonne is 1000 kg. The Falcon 9 weighing "433 t" reads way more elegantly to me.
Here in Canada (where the mixup of metric vs imperial tonnes is common) we just say "metric tonnes" and move on. Everyone here knows that means 1000 kg.
European colleagues regularly go, "what other kind of tonnes are there?" and we get to share the joke of how silly Americans are for still using imperial tonnes.
I've often seen mt written as the units for metric tons.
There's some ODD behavior where people in the US want to fuck up metric units (MB being the obvious in my lifetime non-engineer renaming of the meaning of a unit). I find the MM of finance confusing (not sure of origin). Calling tonnes, metric "tons", seems to be a US confusing thing. Or spelling metres vs meters.
Or creating units that depend on something country specific like football field (is that FIFA (EU), US, Canadian, Aussie).
FTR no-one I know (other than in old school industry about 20 years ago) used the UK 'Ton' any more. One place of work made this clear by having different pronuncication ('Tonn-ey') as they were an old-school foundry. And the spelling is different from wherever I've seen it.
The nuclear industry was using metric weights fully when I did my apprenticeship in it in the late 1980s. Good job really as I think a conversion error could be catastrophic.
Same goes for gallons though, US gallon is smaller than a UK one.
My understanding was that "ton" is the US / imperial and "tonne" is the metric one, but I see people using them interchangeably here, so I guess whether that's technically true or not is a bit moot!
The spelling "tonne" is only used in countries where there might be ambiguity with the short ton. For the rest of the world, "ton" (abbreviation: t) is the metric ton. Technically it's classified as a "Non-SI unit that is accepted for use with SI," like litres or degrees Celsius.
Unless https://www.math.net/pounds-to-tons is severely wrong, a US ton is 2200lbs, UK 2240lbs, metric 2204lbs. Put a different way, US to metric is a <0.2% difference (the smallest), US to UK is a <2% difference (the biggest).
At a scale of 433 tons, it doesn’t really matter much which kind of tons (unless you’re actually doing the rocket science, of course).
US ton is 2000 lb, not 2200. I spent some time in the US and had never heard of a ton meaning 2200 lb. Unfortunately, that's a 10% error off of a metric ton.
The table at right is based on the kilogram (kg), the base unit of mass in the International System of Units (SI). The kilogram is the only standard unit to include an SI prefix (kilo-) as part of its name. The gram (10−3 kg) is an SI derived unit of mass. However, the names of all SI mass units are based on gram, rather than on kilogram; thus 103 kg is a megagram (106 g), not a kilokilogram.
The tonne (t) is an SI-compatible unit of mass equal to a megagram (Mg), or 10^3 kg. The unit is in common use for masses above about 10^3 kg and is often used with SI prefixes. For example, a gigagram (Gg) or 10^9 g is 10^3 tonnes, commonly called a kilotonne.
One context where I have seen this used is carbon stocks, e.g. petagram of carbon (PgC):
