I'm sorry Mr Dragon sir, but in the interests of accounting for the usefulness of tails on all fronts, including length, we have introduced the metric of 'adjusted tail size'. The length doesn't matter.

What matters is:

[(Length x Diameter) + (Weight/Girth)] / Angle of the tip squared ]

When we're talking about tail size, we can't just talk about the length. We need a tape measure, a scale, and a protractor as well.

Now, for dragons, the calculation is actually really simple. Dragons are commonly found sleeping over their hoard or flying, so the angle for their tail size in these times when they are most often 'in action' is what we should be using. As this diagram shows, a dragon's tail most often protrudes at an angle of 0 degrees from the body in flight, and it is much the same at rest. This simplifies things a great deal - as it means that with a 0 in the denominator when adjusting tail size, a dragon's adjusted tail size actually undefined irrespective of how smug, girthy, weighty or long the dragon's tail actually is.

Once again, I'm sorry to be the one to inform you that the dragon tail size is simply undefined for terms of comparison. While we of the Feline Department of Naps [F-DoN] endeavour to make sure that the heads of all our scaley friends are adequately inflated, it is a matter of public & cat interest that dragons can sleep calmly and snugly in the knowledge that they are measuring their tails correctly. It's totally not so we can nap on you because you're warm.