# Tip for verifying scale accuracy



## tom_h (May 6, 2008)

Coins are manufactured to very tight tolerances and can be used to check accuracy of digital scales. This is an essentially "free" alternative to dedicated, special calibration weights.

Standard masses of US coins are published here:
http://www.usmint.gov/about_the_mint/index.cfm?flash=yes&action=coin_specifications

For example, a quarter's mass is 5.670g, and therefore a standard roll (40 quarters) is 226.8g (ignoring the paper wrapper).

This gets a bit impractical for weights above a few hundred g.

I checked my Office Depot model ES11 scale (5,000 g range), and got:

55g of coins, scale reads 54g (about 2% error).
226.8g of coins, scale reads 226g (0.4% error)
453.6g of coins, scale reads 452g (0.4% error).

Not bad.


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## STARNUT (Jun 19, 2005)

Or you could just use one nickel that weighs 5.000 grams calibrate the scale. 


Starnut

Edit: I see you have a scale with a 5000 gram capicity. I have one with a resolution to 0.1 grams with a max of 3000 grams and one nickel was 5.0 grams so........... close enough.. I suspect your error is coming from the useable range of the scale. Kind of like measuring the width of fishing line with a yardstick.


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## tom_h (May 6, 2008)

STARNUT said:


> Or you could just use one nickel that weighs 5.000 grams calibrate the scale.Starnut


Right ... rolls of nickels present a more convenient weight standard.

All my local parking meters use mostly quarters, so I am more likely to have quarter rolls than nickel rolls


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## Touch0Gray (May 29, 2003)

I use a 4 beam Ohaus magnetically dampened balance. As a balance it is easy to calibrate and it accurate to .01 gram. BUT weighing a bicycle would be a bit tough as it only goes to 311 grams. That said, just because a digital electronic scale is accurate at 5 grams, does NOT mean it is accurate at 500 or 5000


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## lalahsghost (Aug 27, 2007)

I have a set of these:


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## Argentius (Aug 26, 2004)

*just make sure...*

you're using uncirculated coins, or, at least, from the last year or two.

Many coins in common circulation are worn from use, and that actually reduces their weight.

If you're estimating the value of precious metal in silver coins, for instance, there's actually a different rule-of-thumb multiplier you'd use for circulated coins.


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