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Comment by beefield | Hacker News Reader

My pet peeve with bathroom scales is that it is impossible to find one that actually does what it claims and has accuracy of +-0.1kg. They do show the measurement to 0.1, but just shifting your weight differently can cause a difference of hundreds of grams. Does anyone knlw a scale that actually measures at 0.1kg accuracy?

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Is it ever significant to know? Your body weight varies naturally depending on food intake, waste disposal, and even when you last went for a hair cut. If sub-kilo variations are medically relevant, I would expect one to measure more than just weight.

I think he's talking about precision, not accuracy.

>Is it ever significant to know?

When making weight for a sport. Any more time than necessary spent dehydrating is energy and recovery you're not going to have for the event.

The best scale I’ve ever had was the Nintendo Wii Balance Board.

A couple of years ago I wanted to upgrade my bathroom scale to whatever the best one was and I found that there are no really good scales out there.

This actually tracks as the Wii Balance Boards needs good sensors to accurately sense how you are shifting your weight. I imagine they use better and more weight sensors than your average bathroom scale.

I have a "smart" scale from Polar that fortunately could be used as a regular dumb scale. I think Polar is really great in this regard. Their watches and other equipment can be used without syncing or connecting to their cloud, but the cloud does provide you extra value if you want to use it.

People confuse precision with accuracy all the time. It's one of my geekier pet peeves.

After a ton of research I got an AccuCheck scale (~$30 on Amazon) which I'm happy with, and at least avoids most of the problems with modern digital scales. Clean minimalist look. Takes 3 AAA batteries.

https://www.amazon.com/gp/product/B084SFRSBD/

It claims 0.1 lb accuracy, and seems pretty repeatable, but I haven't tested it for accuracy. These digital scales have multiple sensors (this one has 4), so it makes sense that individual sensors may give different readings as you shift your weight around - not sure if there's an exact science to combining the 4 readings into the single one that is displayed.

Luckily the exact science is an adding operation, ifi the sensors behave in a linear way, that is.

0.1lb is ~0.5kg so same precision as parent. 0.1kg is 0.22lb, or literally glass half full of water, or slightly less than two Medium eggs, or 2/3 an empty glass itself, or 2/3 an iPhone, etc. 0.1lb/0.5kg/500g is about 16 fluid ounce in water, so it's probably a good balance point.

Your math is off. 0.1lb is ~0.05kg. 0.5kg is ~1.1lb.

0.1kg is the weight of 100ml of water, which is about 3.3oz

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