Why does curtain weight matter?

Curtain tracks and poles have weight limits. Exceeding these causes sagging, difficult operation, and potential failure. As a rough guide, lightweight tracks typically hold around 5-10kg and heavy-duty tracks 20-40kg, but real ratings vary widely by brand and fixing — always check the manufacturer specification and treat your fixings as the weak point.

What does GSM mean for fabric?

GSM is grams per square metre. It measures fabric weight/density. Lightweight sheers are 50-100 GSM. Medium-weight cottons are 150-250 GSM. Heavy velvets and tapestries are 300-500+ GSM. Check the fabric specification or weigh a sample.

How do I find the GSM of my fabric?

Cut a 10x10cm square and weigh it on kitchen scales. Multiply the weight in grams by 100 to get GSM. For example, a 10x10cm piece weighing 2.5g = 250 GSM. Alternatively, check the fabric bolt or supplier listing.

What GSM is standard curtain lining?

Standard cotton sateen lining is 100-130 GSM. Blackout lining is typically 180-250 GSM. Thermal lining is 150-200 GSM. Interlining (bump) adds 150-250 GSM on top of the lining weight.

SewCalcs

Curtain Weight Calculator — Track Load Capacity

Calculate the weight of finished curtains for track load capacity.

Total Fabric Widths

For both curtains combined

Cut Drop

Curtain drop length

Fabric Width

Bolt/roll width — commonly 137cm (54in) for UK curtain fabric

Fabric Weight (GSM)

Face fabric GSM (sheers 50-100, medium cotton 150-250, velvet 300-500)

LiningWhether the curtains are lined (adds the lining layer to the weight)

Lining Weight (GSM)

Cotton sateen lining 100-130, thermal 150-200, blackout 180-250

How We Calculate This

Curtain weight is calculated from the total fabric area multiplied by the fabric weight (GSM), plus the lining weight if lined.

The formula

Fabric area = Widths × Fabric width × Cut drop (in m²)

Fabric weight = Area × GSM ÷ 1000 (in kg)

Total weight = Face fabric + Lining + Interlining + Hardware

Lining and interlining are estimated over the same cut area as the face fabric — a slight over-estimate that errs safely for track load. Hardware (rings, hooks, heading tape) adds a fixed allowance, and a safety factor sizes the minimum track capacity.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify quantities before cutting or purchasing fabric.