[pmontra]

> It’s a slog to do the “which one of these is least a ripoff” calculation, at the grocery store

Where I live price labels must carry the per liter or the per kilo price too. It's printed with a smaller font size but it's visible and it's often the only price I look at.

[xp84]

The unit price labels here in the US are hilariously messed up. The items you want to compare will be say, a pack of 6 granola bars or a 10 pack. The unit prices will be like:

#1: $0.37 / ounce

#2: $6.50 / pound

or even:

#3: $1.82 / each (a price per item)

This will even be common within the same exact brand too. The stores seem so bad at picking a consistent unit for a product category that it seems malicious, but it stretches my belief that they have the time to get it so wrong intentionally.

[asfodelsu]

In many places in Europe: Normal price per item big letters, price per Kg small letters. Problem solved

[netsharc]

I've seen the "unit price" be per 100g (Especially so you don't notice it's a ton of money per kg) so there's still some screwing around...

[jcynix]

Sure but multiplying by ten to get the price per kilo shouldn't be the most complicated thing for even those folks that aren't math savy. It means to move the decimal point (or comma) one place to the right IIRC.

If you had to convert from arms to legs or feet like in certain areas of the world, that might be much harder, of course.

[hahamaster]

I prefer prices per 100g because I mostly buy food that's under one kilo. I'm sure they show prices per 100g just to make them look cheaper but in my case I actually prefer it this way.

[tharkun__]

It doesn't even matter what unit is chosen as long as it is kept the same across.

Comparing Smarties to M&Ms is super easy if both have to use price per pound, price per oz, price per g or price per kg. Who cares if the price per kg would be $0.031.as long as I can see it's $0.028 for the other for the same unit without doing math.

[papichulo4]

Ah, sensible internationally recognized easy to divide units of weight? No thank you comrade!

[teapot7]

Australia too.

[rickdeckard]

Comparable unit-pricing: A mandate brought to you by the European Union. You know, this allegedly evil entity that always hassles with the free market and annoys global companies. /s

[cromulent]

Whilst I am waiting for my number in a chemist, I kill time by finding the highest price per litre. It's normally some anti-aging cream at well over €1000 / l.

[animuchan]

This is not just EU, in our here Middle Eastern country there's the same law. (And also mandatory "high sugar" warning stickers on unhealthy stuff.)

Customer-friendly regulation sure feels nice.

[marcosdumay]

> and annoys global companies

Lol... Meta is doing a huge campaign here in Brazil about how they won't provide us their AI services because they are annoyed by that entity.

It has been quite a help to the government popularity.

[rickdeckard]

In Europe Apple follows the same strategy, but in a more subtle way than a full campaign.

And sadly, it seems they found some audience...

[rvnx]

The same with this "metric system"

[regularfry]

It's malicious compliance. They probably wouldn't show anything other than the pack price if they had a choice, so there's something forcing them to show unit prices. So given that they have to show them anyway, they have an opportunity to inject profitable confusion.

Non-metric units are just icing on the cake.

[rqtwteye]

"They probably wouldn't show anything other than the pack price if they had a choice"

The absolute dream would be to price it like health care. You only find out the price months or years after buying the item and multiple phone calls to clear up errors. And for one person it would be 50 cents and for another person 200 dollars.

[pmontra]

I remember that around year 2000 a coworker from England told me that petrol pumps changed the prices from pounds per gallon to pounds per liter when the cost crossed the one pound mark. There is some malice in that too. Something like that could be the origin of using different units in those USA shops, not to cross some psychological threshold.

It's been a long time since I went to the UK so I can't say if petrol is really sold by the liters there. Maybe somebody from the UK could confirm or refute the tale. Anyway it's probably way more than one pound per liter now.

[kruador]

The UK switched from selling petrol in gallons to litres in the 1980s. I think I just about recall petrol prices suddenly changing dramatically when I was fairly young - I used to help my Dad keep records of how much fuel we'd bought at what price. I'd write down the figures in the book while he went to pay (it was always self-service) so I must have been old enough to be left alone for 5 minutes!

This Energy Institute statistical series - https://knowledge.energyinst.org/search/record?id=58969 - says that their records changed from "new pence per gallon" to "new pence per litre" at the start of 1989. That seems late for my recollection.

Looking back at historical data from https://www.gov.uk/government/statistical-data-sets/oil-and-..., it appears that the average price for "4 star" petrol (97 RON) crossed the £1 per gallon threshold some time in 1979 (Table 4.1.3, and multiply by 4.54609). I'm not old enough to remember that!

By 1989, prices were at 168.8 pence per litre (i.e. £1.68). So I think the story about the change being because it had gone over £1 per gallon has to be a myth. However, retailers certainly weren't complaining about the price displayed being less than one quarter of what it had been! In contrast, they were much less happy about prices per kilogram being more than twice the price per pound (weight).

Prices crossed £1 per litre for 'Premium Unleaded' (95 RON) in November 2007. They fell back below this level in November 2008 but went back up over it in June 2009.

[iam-TJ]

The change-over was actually driven by the technology at the time - namely the outdoor road-facing price advertising panels, as well as many of the pump displays.

Simply - they were only designed to show 2 numbers so when the price-per-gallon exceeded 99 pence many had to stick a static "1" in front, and many point-of-sale terminals and cash registers couldn't handle it.

Since there are ~4.5 litres in a British gallon displaying pence-per-litre brought the displayed prices back to 2 digits and allowed for a gradual transition to 3 and 4 digit displays.

And yes, at the time the switch from pence-per-gallon to pence-per-litre occurred some retailers did take advantage to 'add some profit margin' but it wasn't universal.

[paledot]

Gallons are larger than litres, so in Canada you'll never find anything sold by the gallon. However, pounds are smaller than kilograms, so produce at the grocery store is commonly advertised with per-pound price, with the per-kilogram in small print.

[d1sxeyes]

Or it’s in weirdly sized containers. Like 227g of coffee, or something similar (UK, not Canada)

[pjc50]

It is, and everything is required to be sold in metric units. Except for things like pipe fittings and screw sizes, but even those have to show the metric somewhere.

There's an effort to switch car efficiency from mpg (higher is better) to "l/100km" (smaller is better), because the latter has more intuitive scaling as well as being properly metric.

There were definitely people complaining about the price hike when the currency changed, but that was back in 1971 so it's only boomers who'll bring it up.

[pmontra]

Some pipes are in imperial units in Italy too. For example, from my memories of few days ago at a store: we have metric series of rigid PVC water pipes (32 mm, 40 mm, 50 mm) and imperial series for the flexible ones used for watering plants and grass. I remember sizes of 1/2" 3/4" 5/8" 1" 1 1/4". But there are also metric ones that more or less can fit with some of the imperial ones. Of course there are two series of adapters, hoses, etc.

Gas pipes are imperial. I think they never changed to metric because of safety concerns or because the number of meters sold is lower than water pipes (gas pipes last forever) and it's not worth splitting the market in two. But it's just my suppositions.

[paledot]

I can see bearing a grudge for 50 years over that one, though.

[frameset]

Petrol is around £1.44 a litre at the moment, varying a bit geographically.

[tonylemesmer]

Love that phrase: ‘profitable confusion’. Basically the business model of commodity box shifters

[nerdponx]

When money is at stake, never attribute to incompetence what could be attributed to greed.

[gregw2]

Nice twist on the incompetence version of Hanlon's razor... does it have a name? "Nerdponx's razor" will have a hard time catching on...

EDIT: I see esmifra on Reddit said this six years ago... but not sure "esmifra's razor" would catch on either. https://www.reddit.com/r/wikipedia/comments/8itqf5/comment/d...

And I see there is a similar but less catchily-worded concept, "Hubbard's corollary" from 2020 mentioned in the Wikipedia entry for Hanlon's razor... https://en.m.wikipedia.org/wiki/Hanlon's_razor

[nerdponx]

I actually thought I made it up, and almost called it "Nerdponx's Razor", but I thought it would be arrogant to name it after myself. Hubbard can take the credit!

[Damogran6]

Oh, they have plenty of time to do it. We have created lots of MBAs...people who want to take advantage of their education, and to do so they want to squeeze a little more profit. And they're bored. And they need to stand out from their coworkers. Therefore 'price per net weight' becomes a thing. And Surge pricing.

(Peanutbutter M&Ms are an egregious example...the share bag price varies 20% depending on the calendar, as does Hilshire Farm Kielbasa...which now comes in 14 oz packages...which is a choice and means a family of 4 needs to buy two of them now to make a meal.)

[wannacboatmovie]

> as does Hilshire Farm Kielbasa...which now comes in 14 oz packages

Your grievance reminds me of this classic phone call:

https://www.youtube.com/watch?v=f4RNb3tt0LM

[AceyMan]

Well, Peanutbutter M&Ms are sacred manna, so they are a bad example.

At my Ralph's (=Kroger), all the large bags dissappear minutes after getting loaded into the shelf.

[jjeaff]

it has to be intentional. almost any two products that you might want to compare are always using different units. haagan Daaz pints are always shown with different units than the larger haagan daaz.

[gambiting]

They have to do that in the UK too, but unfortunately the law doesn't seem to standardise the unit for these comparison values(or it does and is ignored).

If you have two packs of coke cans next to each other, and one gives you a price per 100ml, and the other per can, it doesn't help that much(yes you could multiply the value per 100ml by around 3x, but at a glance the difference isn't obvious).

[dwighttk]

At my store they are free to choose their unit and they strive for unit heterogeneity within a specific product you might want to compare

[MathMonkeyMan]

That's a good store.

My store has a few different brands of coconut milk. Some of the unit prices are per pound, while others are per quart. I make the approximation that coconut milk has the same density as water, which is two pounds per quart. The unit prices are all odd three digits numbers. It's a pain.

You could have one person who works in an office somewhere who's responsible for itemizing inventory for the whole grocery chain. They could solve this problem (maybe automatically!) with a spreadsheet. They could also solve the problem of tomatillos not being registered in the self-checkout catalog. But what is that person's salary paying for in the company's eyes?

To be fair, maybe the real explanation is "lots of stuff, shit happens." And it's only a factor of two (for watery goods, anyway).

[vkou]

Where I live, labels get these price per amount labels...

But they don't keep the denominator consistent, even across the same category of product.

So I get to compare a price/oz, versus a price/lb versus a price/serving and all the while, I contemplate why nobody's interested in burning the whole store down.

[1oooqooq]

but even with the label you don't know if the cheaper one is full of sugar or is mostly water etc... there's no escape.