Cycling jersey weight ranges from about 80g for ultralight race models up to 350g for thick thermal versions. The number gives you a quick read on where a jersey falls on the warmth spectrum, but it's not a quality score. A lighter jersey isn't automatically better — it's just built for a different purpose.
For hot-weather riding, look at jerseys under 180g. The sweet spot for most summer jerseys is 120–180g, which balances breathability with enough substance to feel substantial. Under 120g is ultralight race territory: incredibly cool, but often more fragile and less versatile. For spring and fall, 180–250g midweight jerseys add a bit of warmth without full thermal construction. Over 250g typically means a winter jersey with insulating or wind-blocking fabrics.
The key is matching weight to when and how you ride. Don't chase the lightest number if you need durability for daily commuting, and don't grab a featherweight if your early mornings run cold.