Convert fabric weight between GSM and oz/yd², see whether a knit reads as light, mid or heavyweight, and estimate a finished garment's weight from its GSM and surface area. The GSM–oz conversion is exact; garment weights are an indicative planning aid — confirm the real figure against a knitted sample.
⚠️ Conversion is exact; garment weight is indicative. The GSM ↔ oz/yd² conversion uses the fixed textile factor 1 oz/yd² = 33.906 g/m², so it is exact. Garment-weight estimates multiply GSM by an approximate surface area and ignore seams, trims, finishing and shrinkage — treat them as planning figures for yarn budgeting and shipping, then confirm the real weight against a knitted sample.
Every GSM ↔ oz/yd² result here comes from a single fixed constant: 1 oz/yd² = 33.906 g/m². Divide GSM by it for ounces, multiply ounces by it for GSM. No rounding tricks, no ranges.
Under 180 GSM reads light, 180–300 mid, over 300 heavy. It is a starting frame for how a knit will feel — gauge, fibre and finish move the real hand, so use it to steer, not to spec.
Multiply fabric weight by the garment's total surface area in m² to estimate grams per piece (250 GSM × 0.7 m² ≈ 175 g). Handy for yarn budgeting and shipping — but it is an estimate.
Seams, trims, ribs and finishing shift the finished weight. A knitted swatch or sample gives the true GSM and grams per piece before you lock a costing — that is the number production runs on.
Budgeting a run too? Pair this with the knitwear cost calculator and split each colourway across sizes with the size run calculator. New to production? See our manufacturer for startups and small-batch production pages, or start at the knitwear manufacturer overview.
Use the exact factor 1 oz/yd² = 33.906 g/m². To go from GSM to ounces, divide by 33.906 (for example, 250 GSM ÷ 33.906 = 7.37 oz/yd²). To go the other way, multiply your oz/yd² figure by 33.906. This calculator does both instantly and also shows the weight class — the conversion itself is exact, not an estimate.
As a planning guide, knit fabric under about 180 GSM reads as lightweight (fine-gauge tops and summer knits), 180–300 GSM as midweight (most everyday sweaters and cardigans), and over 300 GSM as heavyweight (chunky gauges and knitted outerwear). These bands are indicative — gauge, fibre and finishing all shift how a fabric actually feels in the hand.
Multiply the fabric weight in GSM by the garment's total surface area in square metres — for example, 250 GSM × 0.7 m² ≈ 175 g. It is a useful planning figure for yarn budgeting and shipping, but it ignores seams, trims and finishing, so treat it as indicative and confirm the real weight against a knitted sample before costing a production run.
Weight drives yarn consumption, and yarn is usually the largest single cost in a knit garment — a heavier GSM means more yarn per piece and a higher unit price, plus higher shipping weight. It also defines the hand and drape a customer feels. At Kiwi Giyim we confirm the target GSM on a knitted sample before production, which starts at a 250-piece minimum per colour, per size.
Send your tech pack (or use our free template) with the fabric weight you're aiming for and we'll reply within one business day with pricing, a sample timeline and an honest read on whether that GSM and target cost work together.