Short answer: for most wrists, 48mm is genuinely large — but the number on its own does not decide whether a watch fits. Two 48mm watches can sit completely differently.
Why is diameter the wrong measurement?
Because a watch fails on your wrist from front to back, not side to side. Lug-to-lug — the distance from the top lug tip to the bottom one — is what determines whether the case overhangs the flat part of your wrist. A 48mm case with short, steeply curved lugs can measure less lug-to-lug than a 44mm case with long straight ones, and it will wear smaller despite the bigger number.
Measure the flat top of your wrist. If your lug-to-lug exceeds it, the watch will rock and the lug tips will dig in.
What wrist size handles 48mm?
Comfortably, around 7.5 inches and up. Between 7 and 7.5 it works if the lug-to-lug is under about 52mm and the case is not also very thick. Under 7 inches it will look deliberate — which some people want, and that is a legitimate choice rather than a mistake.
Does thickness matter as much?
More than people expect. A 48mm case at 11mm thick reads as a big flat disc; at 15mm it reads as a block. Thickness is also what stops a watch sliding under a shirt cuff — for most sleeves the limit is around 13mm regardless of diameter.
Watches built around a domed dial are always thick, because the depth effect needs the space. That is the trade you accept with the style, and it is worth knowing before rather than after — see planet dials explained for why.
How do you check without buying?
Cut a circle of paper at the diameter, mark the lug-to-lug length, and tape it to your wrist for ten minutes. It looks ridiculous and it is the single most useful thing you can do. You will know within a minute whether the footprint works.
Should the strap change with the size?
Yes. A wide case on a narrow strap looks top-heavy. Tapering straps — wider at the lug, narrower at the buckle — carry big cases better than parallel ones, which is why most large watches ship that way. The P6676 is a 48mm case at 15mm on a 24mm-to-20mm taper; the colour guide shows how the different strap colours change how large it reads.