German with a scientific background. I can deduce the meaning of the words but I’ve never seen them used. I’m not even sure these units of measurement were mentioned when these were discussed. Most stuff is ton, kilogram, gram, miligram, microgram; kilometer, meter, centimeter, milimeter, micrometer. Rarely decimeter are thrown around.

Decilitres/centilitres are relatively common, but they’re the only ones that come to mind.

In Romania we use them for measuring areas. An “ar” is 100m^2 or a square decameter, and a hectare is a 10000m^2 or a square hectometer.

In Austria, some things like ground beef are ordered in decagrams. My wife used to get confused responses when she tried that in Germany :).

We use litres, which is one decimetre cubed. We use hectares, which is one hectometre squared. But the beauty of it is, that you can just convert everything to units that are more widely understood.

• 1 decimetre = 10 centimetres = .1 metres

• 1 hectometre = 100 metres = .1 kilometre

I used to do land surveying in Canada and we’d use “decs” for decimetres when laying out points. You’d put down the rod, they’d tell you something like “dec and a half left” then you’d move closer and it’d be “two cents right” and you’d be even closer and then it’s like “3 mils right.” Then you’d take the shot and they’d tell you how much closer or farther you’d have to go to get the point. If you were way off to the point where you might have tens of metres, usually for rough layout we’d rarely use “dee-kays” for dekameters, but typically it would be just “30 metres north”.

In Italy we use hectograms (“ettogrammi”, “etti” for short) in day to day life when buying groceries. You don’t ask for 200 grams of ham, you just ask for 2 etti.

I can only tell you about how we do it here in the Netherlands, but very rarely.

We have highway location markers (in the form of a little pole and a sign with some markings on them) every hundred meters. Their official name is “afstandspaal” but people generally call them “hectometerpaal” because they denote the distance along a highway in hectometers.

When you hear about traffic jams, speed cameras, or car accidents on the radio, they’ll usually announce highway number and hectometer pole number so drivers know where to look.

The metric tonne (1000kg) is used rather than a megagram even though megagram is more fun to say. This is for historic reasons, mostly. Having Mg (megagrams) and mg (milligrams) next to each other would probably also just confuse people.

Hectares (100x100m, or 10000m²) are used to denote area for things like farms. Centiliters and deciliters are used for very specific purposes (medical and such).

As for general distance: meters and kilometers work fine. Same with grams and kilograms. Smaller measurements like centimeters and millimeters are also common (or milliliters and liters, rarely centiliters but you do see them in some recipes).

Funnily enough, we (although I notice it mostly among older people) do use ons and pond (ounce and pound), although an ons is 100 grams and a pond is 500 grams. Just like with the tonne, we adjusted them to make dealing with SI units easier; we did the same with the mijl (mile) and other units similar to the imperial name as a transition to the normal metric system. Technically speaking, you’re not allowed to sell advertise products by the ons or pond anymore (thanks, IJkwet of 1937) but if you ask anyone at market for a pound if cheese, they’ll know how much to get you.

Lastly, there are a few use cases where the inch is used. Screens are measured in inches for reasons I’m not entirely sure about (probably British and American exports). This leads to some rather silly phone spec sheets, listing width/length/height in centimeters and a screen diagonal in inches. We don’t even use a Dutch word for inch!

From my experience in Norway, these are typical in context of daily speech:

Weight (gram): tonne (a substitute name for Mg (Mega)), kg, hg, g, mg, μg (mostly in medicine)

Distance (meter): mil (10 km), km, m, dm (kinda rare), cm, mm

Volume (liter): l, dl, cl, ml

In my experience, the deca-predix is very rarely used. Most of the missing prefixes are just substituted for numbers, i.e. saying “a thousand kilometers” is much more common that “a megameter”. Of course, this differs depending on context, as a lot of the prefixes become more common within scientific fields where the sizes are common.

On a separate note, even the numbers can be a bit inconsistent. It has bothered me that it’s often common to say “a thousand milliard” instead of “one billion” (also note that we use the long scale).

I think hectare, decibel are few of them?

in school in austria we teach dezimeter (tenth of a meter)

In America, I’ve seen nurses and diabetics use deciliters in reference to medication or concentration before.

These two specifically - I don’t think I’ve ever seen them.

Hectoliters are sometimes used e.g. for measuring beer consumption for an event, decimeters in some informal contexts, some country commonly describe drink sizes in centiliters or deciliters.

Centimeters are common, I’d say more common than millimeters in informal context.

As an American who has gotten very used to metric units in studying engineering, the general rule I picked up is that you typically only change units every three orders of magnitude. So 8 decameters would typically be expressed as 80 meters, maybe 0.08 kilometers. Decameters and hectometers are a thing, but they’re not common units. Even centimeters don’t see much use compared to millimeters.

For distance, no. Day to day we use mm, cm, m and km. But in more specialised settings (e.g. construction) I’ve seen sometimes decameters.

For weight yes, grams, hectograms, kg, tons. Liquids is usually ml, cl, liters, hectoliters (not sure it’s spelt that way).

In labs I’ve also seen also micro and nano of all three units.