Is 7 inch girth big?
Yes — a 7-inch (17.78 cm) erect girth is off the measured chart entirely, approaching a soda can, which runs about 8.25 inches around.
Grab a soda can. It runs about 8.25 inches around (21 cm). A 7-inch girth (17.78 cm) is closing in on that — which is exactly why no clinical dataset has ever logged one.
The largest measurement study on record, Veale et al. (2015, 15,521 men), puts mean erect circumference at 11.66 cm with a standard deviation of 1.10 cm. Seven inches sits more than five standard deviations above the mean. At that distance the model stops estimating and starts inventing; there is no meaningful percentile left to quote.
That points to the likelier story: the tape. Wrapping over the flare of the head, angling the tape, or leaving slack can add a full inch to a girth reading. Before filing yourself next to a beverage container, spend two minutes with the proper measuring method. Snug tape, thickest part of the shaft, level wrap.
If a careful re-measure still says 7, no off-the-shelf condom chart reaches you. This is the closest the industry gets.