A Discussion on Spray Can ‘Weights’

Why does a 12 ounce spray can of paint not weight 12 ounces?

Occasionally we get questions about the weight of a spray can.  Mostly commonly customers ask “why does a 12 ounce can of paint not weigh 12 ounces?”  The key point to understand is that paint is a liquid and it is typically measured by VOLUME.  So spray cans identify content by volume (NOT WEIGHT).  And since a liquid  is typically measured by volume, the volume does not include the weight of the can.


Let’s talk about WEIGHT for a moment:  In addition to the weight of paint, weight is also comprised of the weight of the can itself as well as the weight of reducer and propellant.  Paint by nature is very thick – in fact it is typically too thick to apply or even spray.  Reducer is a required additive that decreases viscosity so that the paint will spray.  Propellant creates pressure inside the can and it is the ingredient that allows the can contents to spray out of the can.  Additionally, paint ‘weights’ can have significant variations.  Primers, clearcoats and light colors are generally heavier (more viscous) than darker colors of paint.

What you are getting when you purchase a spray can

So what are you getting when you purchase 12 ounces of ‘paint’ from us or one of our competitors (even auto parts stores offerings)?

-Reducer & propellant: 8.5 oz by volume
-Paint/primer/clearcoat: 3.5 oz by volume

As you can see, reducers and propellants are the majority of contents by volume (and weight), not only in spray paints but also for primers and clearcoats.  Our specifications call for 100 grams (3.5 oz by volume) of paint per can.  And the canning system we (and our competitors) use will allow a maximum 3.5oz volume of paint to be dispensed, and we tend to ‘fill to the brim’ the dispensing cap with paint.  The weight by volume of liquid paint will vary depending on how thick (viscous) the paint is (this is why some cans will appear to have ‘less’ paint/primer/clearcoat in them.

Here are the total (gross) weights of our products:

-Spray paint (12 oz by volume): approx. 13.5 oz gross weight
-Primer and Clearcoat (10 oz by volume): approx. 14 oz gross weight

So why does a can labeled with 12 oz ‘weigh’ as much as a 10 oz can?

So why does a can labeled with 12 oz ‘weigh’ as much as a 10 oz can?  This all has to do with the definition of ‘ounces’:  ounces can be used to measure weight OR fluid (liquid) volume.  When we look at the label on a spray can, many times we assume that 12 ounces is the WEIGHT OF THE CAN AND CONTENTS.  However, the actual definition is the VOLUME OF THE CONTENTS!  Furthermore, it is important to note that, practically speaking, the only liquid that both weighs 1 ounce by weight AND volume is water – most other liquids will be ‘heavier’ or ‘lighter’ by weight.  Paint, reducer and propellants are all ‘lighter’ than water.  However they all have the same volume.  And this is why a can of spray paint actually weighs less than primer and clearcoat.

Incidentally, we have MSDS sheets (data sheets) for all of these products, and these are also available to you upon request.  And rest assured, you ARE getting your money’s worth when we sell you 12 ounces of paint!  Just be aware that the recipe or formulation includes paint, reducer and propellant.

Need some spray can car paint? Visit ERA Paints Store for premium quality paint and accessories.