I’ve been using this scale for about five years, assuming it’s been accurate. My new (guy) room mate gets on the scale and has a fit. “There’s no way I only weigh 140!” He swears the scale is off by ten pounds, which upsets me greatly and means that I just gained ten pounds! So, I weigh a four lb bag of sugar and the scale registers…4 lbs! Whew. So I’m right; however, the room mate still contends that the scale is capable of such small weights, but becomes inaccurate at people sized weights. I say this is bullshit. What say you? Thank you.
Your roommate is right.
My home scale reads ten pounds low. I know this because for a while I was weighing in on a hospital scale which I’m sure was pretty accurate.
Sorry.
While I obviously know nothing about your particular scale, there is no reason to trust a 4-lb calibration all the way up at 140 lb. Also, when you say it read “4 lb”, what did it actually read? 10 lb of error at 140 lb is only 7%, so 4 lb might only turn into 3.7 lb, which rounds to 4 lb if only one digit is shown.
(That is, the error need not be a fixed shift. It can be proportional to the weight.)
But I know, for a fact, that if I weighed 120, there’s no way I could fit into the pants I’m currently wearing. Honestly! This is a fact. Why would the scale be accurate on a four lb bag of sugar and not for my weight?
If you’re in doubt, go to a hospital or gym and weigh yourself there.
Or just go with 110 and be happy about it. I won’t tell if you won’t!
It is probably bullshit. But the only real way to tell is to measure your self with other scales. Do you have access to a gym. They usually have balance scales that are pretty accurate.
But…you didn’t gain 10 pounds, even if your roommate is right. You weigh the same as you always have (or whatever), but that number is higher than you thought.
Anyhow, this is all speculation on our part. I have no idea how accurate your scale is.
Do you know that? Or, do you know this: “If I weighed an amount such that my scale showed 120 lb, I’d never fit into these pants.” That seems like a solid claim. But that’s a different claim to “If I weighed 120 lb…”
If you and somebody else together would have a low enough weight that you could get on the scale at the same time, you could try weighing you, the other person, and the two together, and see if adding your individual weights equals the total weight. If it doesn’t, this demonstrates inaccuracy.
A different version of this strategy is to start stacking 4 lb bags of sugar on the scale until you get up to 140 lbs. This would fix the very reasonable objection that Pasta points out. But even if you don’t keep 140 lbs of sugar on hand at home, you might be able to try the first idea. Consider enlisting children and the like.
Yet another version of this is to test whether the bag of sugar, or maybe something heavier like two filled gallon containers or a filled bucket, seems to weigh the same by itself versus when added to you.
Because the gain is off.
Is this an analog scale? Is there a “zero adjustment knob” on the scale?
There’s not much you can do about a gain error. But if there’s a zero adjustment knob, you may be able to at least minimize the error in a more useful range.
On analog scales, most people adjust the zero knob so that it reads 0 lbs. when nothing is on the scale. But this should not be done. Instead, you should set a *known *weight on the scale (preferably one between 100 and 150 lbs.), and then adjust the zero knob so that the scale reads correctly. It will be inaccurate at 0 lbs., of course, but you don’t care about that. One idea is to weight yourself at a gym or doctor’s office, and then (within a few hours) use your body weight to adjust your scale’s zero knob.
On digital scales, there may or may not be a zero control knob.
a scale for a person would likely be inaccurate at 4 pounds. get on the scale and read your weight. hold the bag of sugar. if it is 4 pounds greater then that is a good indication that it reads OK for a human mass.
Perfect. Going to try it right now on my room mate, 'cuz he doesn’t care if I see how much he weighs!
Never mind. He won’t participate. This is a stupid argument anyway, I guess. He doesn’t want to weigh only 140 and I don’t want to weigh 120. Either way, I can NOT believe that even a crappy number-showing scale with a little pointer could be off by TEN POUNDS!
First, if you keep your 5 year old scale in the bathroom, exposure to moisture might have affected its innards.
Second, it’s not essential that a home scale is accurate, as long as it’s consistent. You are using it to provide a baseline for your weight, and to see if you have gained or lost. Put the scale on the same place on the floor for each weighing. Variations in the floor can fool it.
You weigh whatever your home scale says you weigh. The solution to your problem is simple. Get rid of the insensitive lout who is trying to control you by making you dissatisfied with what your scales tell you. You and your scales have a history; you get along well; you trust them and they are happy with you. The new bozo has apparently just moved in and has immediately begun creating discord. Lose him like a bad habit; you don’t need the grief he is causing you. The next thing you know, he will be telling you that your favorite pants make your ass look big; beat him to the punch and tell him his talking makes his brain look shriveled. Throw him the hell out and regain your harmony.
PS: I’m absolutely serious about this.
only one person needed. weigh self, grab sugar bag off sink and it should be 4 more pounds. you can step off and pick bag up if needed.
good to know how good it is.
clothing can be 5 to 10 pounds also if not dry nude weighing.
That proves nothing at all. If the scale is 7% out then holding the 4 lb bag of sugar is going to show an increase of 3.72 lbs which is close enough to 4 that you won’t be able to tell anything. There is also the problem that a bag of sugar that weighs a nominal 4 lbs might not actually weigh 4 lbs in the first place.
There are other possibilities. Perhaps the scale is off by about 5 lbs and the scale the room mate had been using and getting his mental calibration from was reading 5 lbs over. Maybe he really weighs 145 lbs and you weigh 115 lbs.
Let’s say I get on a scale and it reads 1000 lbs. I then pick up a 4 lb. bag of potatoes, and it reads 1004 lbs. So you’re saying the scale is O.K.?
You’re confusing linearity with accuracy. 
Suffice to say, the only way to really know if it reads correctly is to calibrate it with known weights.
then use a 10 or 20 pound weight from exercising equipment if available.
Since we are talking about home scale accuracy, let me relay an experiment I tried. My bathroom scale is so good at reproducing my weight that it made me suspicious. It reads to 0.2 lb which is - well, it’s less than 1/10% of what I weigh. That it would always reproduce that last digit in reweighings isn’t plausible (for one thing I should be closer to the odd fractional pound half the time, so nearly always reproducing the last 0.2 suggests a precision better than 0.1).
So I tried weighing myself, then weighing myself while holding about 5 lbs of weight (which gives a different value we can forget), then weighing myself without the weight again. Using this protocol, the scale varies over about 0.4 lbs.
I think the maker programmed the thing to repeat the last value if the new value is not different by some threshold much bigger than the resolution.
Which is actually pretty understandable. I much prefer to have a couple of digits that are not fully meaningful in an instrument, so I can evaluate precision in various ways without trying to peek around a big rounding error. But probably having a digit that does not reproduce in subsequent measures mostly just generates complaints about bathroom scales.