Convert between paper weight measurement systems used globally in printing and packaging. Essential for comparing paper specs across different standards and markets.
⚠️ Basis weight conversion assumes 25"×38" ream size (US standard). This varies by paper grade (bond, cover, index, newsprint, etc.), causing different conversions. Thickness estimate (gsm × 0.00012 mm) is approximate and depends on paper density, caliper, and finish. Always verify with supplier specs.
Last updated: March 2026 | By Patchworkr Team
Paper weight measurements vary globally, causing confusion in international trade. GSM (grams per square meter) is the metric standard used in most countries. Basis weight (lbs) is the U.S. standard, measured as weight of a 500-sheet ream of paper at its basic size (usually 25"×38"). Understanding these systems is essential for international paper procurement and specification matching.
Typical copy paper is 80 GSM (20 lbs basis). Index cards are 110 GSM (24 lbs). Card stock ranges 200-300 GSM (65-110 lbs). The relationship between GSM and basis weight is not linear because it depends on the ream basis size. A GSM rating of 60 doesn't equal 60 lbs basis weight; it's actually about 16 lbs basis weight.
Paper suppliers worldwide may list weight in different systems. This calculator bridges the gap, allowing specification comparison regardless of origin. Knowing your paper's weight helps predict feel, durability, printing quality, and equipment compatibility.
Convert paper weight standards:
Example 1: Standard Copy Paper
Example 2: Business Card Stock
Example 3: Cardstock
Historical reasons. U.S. paper industry developed independently using basis weight. Most countries adopted metric GSM. Today both systems coexist in trade.
Not necessarily. Heavier paper is stiffer and more durable, but quality depends on fiber content, coating, and brightness. 80 GSM premium bond outperforms 100 GSM newsprint.
Basis weight assumes a specific sheet size (usually 25"×38"). Different basis sizes exist for different paper types, making conversions complex.
Most printers handle 75-90 GSM (20-24 lbs) without issue. Check your manual. Heavier stock may jam or damage feed mechanisms.
Lightest: 30-40 GSM (airmail/tissue). Heaviest: 400+ GSM (cardboard/posterboard). Most office use falls 60-130 GSM.
Yes. Heavier paper costs more per ream and uses more ink/toner. Shipping also increases with weight. Balance cost against durability needs.
Yes, but it affects handling and appearance. Mixing creates texture variation. Professional documents typically use consistent weight throughout.
Weigh a known area precisely (1 sq meter or 1 sq foot), then calculate. Or compare sample feel to known weights. Most suppliers provide specs.
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