I can tell the difference betweeen a quantity and the presence of a quality.

* rapido - speed / rapideco - quickness
* longo - length / longeco - longness
* pezo - weight / pezeco - heaviness

I thought the same followed for grand-. Then, the correct word for size would be grando. But grando refers to all of the words on the left side above. It means physical quantity. How do I say size then? I searched both PIV and reta-vortaro and found no entry with a definitiom which matches what I am looking for.

> 
> *Mi volas aĉeti ĉi tiun ĉemizon, sed mi ne trovas mian grandecon.*
> 
> 
> 

Is this sentence correct?