[hermitdev]

Pedantically, at least a standard US football field is an exact size (120yds long, 53 1/3 yds wide).

Soccer pitches? Not so much ... FIFA states the field of play for international matches should be 100-110m long and 64-75m wide (tolerances are relaxed to 90-120m long by 45-90m wide - which oddly means you could have a square pitch). If one would like an example of a comically undersized pitch, look to NYFC playing at Yankee stadium - they had to get a special exemption from MLS, IIRC.

Still useful, though, and I think a reasonable person with familiarity with either soccer or football would get a rough idea.

Please don't take this as criticism ; it's not meant to be. The mention of football and soccer fields being used as a measure of size in the same sentence sparked recollection of some not-otherwise-useful knowledge stuck in my brain.

[cptskippy]

I don't think anyone uses them as exact units of measure but rather to communicate a size in relatable terms. When you relate scale to something familiar it elicits connotations from an individual's experience that makes things easier to comprehend.

Most people have seen a football or soccer field and understand the approximate size.