{"id":5328,"date":"2026-05-04T09:42:38","date_gmt":"2026-05-04T09:42:38","guid":{"rendered":"https:\/\/kangchuangpapers.com\/?p=5328"},"modified":"2026-05-07T10:06:54","modified_gmt":"2026-05-07T10:06:54","slug":"raft-paper-gsm-guide","status":"publish","type":"post","link":"https:\/\/kangchuangpapers.com\/de\/raft-paper-gsm-guide\/","title":{"rendered":"Kraft Paper GSM Guide: How to Choose the Right Basis Weight for Your Application"},"content":{"rendered":"<p>Kraft paper GSM (grams per square metre) measures the basis weight of paper \u2014 heavier GSM means thicker, stronger paper. Common <a href=\"https:\/\/kangchuangpapers.com\/de\/product\/kraft-paper\/\">kraft paper<\/a> ranges from 30 GSM (lightweight tissue and food wrap) through 80 GSM (standard mailing wrap) to 300+ GSM (heavy industrial liner and structural board). The right GSM depends on application: food contact uses 40\u201380 GSM, mailing and gift wrap 80\u2013120 GSM, void-fill 70\u2013100 GSM, corrugating medium 100\u2013180 GSM, and outer liner 150\u2013300 GSM.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Kraft Paper GSM Reference Chart<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th><strong>GSM Range<\/strong><\/th><th><strong>Equivalent (lb\/ream)<\/strong><\/th><th><strong>Typical Application<\/strong><\/th><th><strong>Strength Indicator<\/strong><\/th><th><strong>Common Use<\/strong><\/th><\/tr><\/thead><tbody><tr><td>30\u201350 GSM<\/td><td>20\u201334 lb<\/td><td>Tissue, food interleaf, light wrap<\/td><td>Mullen 8\u201318 psi<\/td><td>Bakery interleaf, tea bags, lightweight wrap<\/td><\/tr><tr><td>50\u201370 GSM<\/td><td>34\u201347 lb<\/td><td>Bag paper, light gift wrap<\/td><td>Mullen 18\u201328 psi<\/td><td>Sandwich wrap, light retail bags, butcher paper<\/td><\/tr><tr><td>70\u201390 GSM<\/td><td>47\u201361 lb<\/td><td>Mailing wrap, void fill, light bags<\/td><td>Mullen 28\u201340 psi<\/td><td>E-commerce packing, kraft mailers, light shopping bags<\/td><\/tr><tr><td>90\u2013120 GSM<\/td><td>61\u201382 lb<\/td><td>Premium gift wrap, heavy bags<\/td><td>Mullen 40\u201355 psi<\/td><td>Retail kraft bags, premium void fill, gift wrap<\/td><\/tr><tr><td>120\u2013150 GSM<\/td><td>82\u2013102 lb<\/td><td>Light corrugating medium, heavy wrap<\/td><td>Mullen 55\u201375 psi<\/td><td>Inner fluting, heavy duty wrap, light cartons<\/td><\/tr><tr><td>150\u2013200 GSM<\/td><td>102\u2013137 lb<\/td><td>Standard corrugating, light liner<\/td><td>Mullen 75\u2013110 psi, ECT 26\u201332<\/td><td>Corrugating medium, inner liner, light boxes<\/td><\/tr><tr><td>200\u2013250 GSM<\/td><td>137\u2013171 lb<\/td><td>Heavy testliner, outer liner<\/td><td>Mullen 110\u2013150 psi, ECT 32\u201340<\/td><td>B-flute liner, retail boxes, light cartons<\/td><\/tr><tr><td>250\u2013300 GSM<\/td><td>171\u2013205 lb<\/td><td>Heavy outer liner, kraftliner<\/td><td>Mullen 150\u2013200+ psi, ECT 40\u201355<\/td><td>Heavy duty boxes, single-wall liner, structural<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>What GSM Actually Measures<\/strong><\/h2>\n\n\n\n<p>GSM (grams per square metre) is exactly what it sounds like: cut a perfect 1m \u00d7 1m square of paper, weigh it, and that weight in grams is the GSM. An 80 GSM paper means 80 grams per square metre, which translates to roughly 0.10\u20130.12 mm thickness for typical kraft. The same paper at 200 GSM runs 0.25\u20130.30 mm thick.<\/p>\n\n\n\n<p>Two papers at the same GSM can have different thickness depending on bulk \u2014 measured as caliper divided by basis weight. A bulky uncalendered kraft at 100 GSM runs around 0.15 mm; the same 100 GSM after calendering (passing through pressing rollers) compresses to 0.11 mm. For applications where stiffness matters more than mass, bulk matters as much as GSM.<\/p>\n\n\n\n<p>North American spec sheets often list basis weight in pounds per ream \u2014 but the ream size varies by paper grade. A &#8217;40 lb&#8217; kraft (40 pounds for 500 sheets at 24 \u00d7 36 inches) equals roughly 65 GSM. The conversion isn&#8217;t intuitive, which is why the global trend is toward GSM as the primary spec.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>How GSM Maps to Strength<\/strong><\/h2>\n\n\n\n<p>Higher GSM generally means higher strength, but the relationship isn&#8217;t perfectly linear and depends on fibre type and processing. Three strength tests dominate kraft paper specifications:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Mullen Burst (TAPPI T 403): pressure that bursts a clamped sample. 80 GSM kraft typically tests 28\u201340 psi; 200 GSM tests 110\u2013150 psi. Reported in psi in North America, kPa in Europe (1 psi = 6.895 kPa).<\/li>\n\n\n\n<li>Ring Crush (TAPPI T 822): compressive strength of a paper ring, predicting how the paper performs as corrugating medium or liner. Reported in lb\/in or N\/m.<\/li>\n\n\n\n<li>Edge Crush Test \/ ECT (TAPPI T 811): compressive strength of corrugated combined board, derived from liner and medium specifications. Reported in lb\/in.<\/li>\n<\/ul>\n\n\n\n<p>For pure kraft paper specs (uncombined, not corrugated), Mullen and ring crush are the primary measures. ECT applies to finished corrugated board where multiple papers are laminated to fluting.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Choosing GSM by Application<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Food-Contact Wraps (40\u201380 GSM)<\/strong><\/h3>\n\n\n\n<p>Sandwich wrap, bakery interleaf, butcher paper, and grease-resistant food sheets typically run 40\u201380 GSM. The priorities are food-contact safety (FDA 21 CFR 176.170 in the US, EU 1935\/2004 in Europe), grease resistance (often achieved via PE coating or proprietary grease-resistant coatings), and printability for branding. Strength matters less because the wrap holds light items briefly.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Retail Bags and Mailing Wrap (70\u2013120 GSM)<\/strong><\/h3>\n\n\n\n<p>Standard kraft shopping bags run 80\u2013110 GSM; heavy-duty retail bags reach 120 GSM. Mailing and shipping wrap typically lands in 70\u2013100 GSM territory \u2014 strong enough to protect contents, light enough to keep shipping cost down. E-commerce applications increasingly favour 80 GSM with internal void-fill paper rather than heavier outer wrap. Mullen burst above 35 psi is a reasonable threshold for shipping reliability.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Void Fill and Protective Wrap (60\u2013100 GSM)<\/strong><\/h3>\n\n\n\n<p>Void-fill paper for e-commerce shipping uses 60\u201380 GSM honeycomb-perforated kraft that expands when crumpled. Protective wrap for furniture and large items runs heavier at 80\u2013100 GSM. Lower GSM gives more volume per unit weight (better packing economics), but too low and the paper tears under cushioning load.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Corrugating Medium (100\u2013180 GSM)<\/strong><\/h3>\n\n\n\n<p>The fluted middle layer of corrugated board typically runs 110\u2013150 GSM for standard B-flute and C-flute applications, up to 180 GSM for heavy double-wall containers. Recycled-content medium dominates this segment because the fluted layer doesn&#8217;t need cosmetic appearance. Ring crush and CMT (concora medium test) are the relevant strength specs.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Outer Liner (150\u2013300 GSM)<\/strong><\/h3>\n\n\n\n<p>The outer faces of corrugated boxes typically run 150\u2013250 GSM for standard packaging, 250\u2013300 GSM for heavy-duty industrial containers and structural shipping boxes. White-top kraft liner (kraft on the back, white on the print face) is common at 150\u2013200 GSM for retail-display packaging. Outer liner Mullen burst typically exceeds 100 psi and ECT contribution drives the box compression strength rating.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Virgin vs Recycled Fibre at the Same GSM<\/strong><\/h2>\n\n\n\n<p>Two papers at identical GSM can perform very differently depending on fibre type. Virgin kraft (made from fresh softwood pulp) has longer fibres \u2014 typically 2.5\u20133.5 mm \u2014 that interlock more strongly. Recycled kraft has shorter fibres averaging 1.0\u20131.8 mm because each recycling cycle shortens fibres.<\/p>\n\n\n\n<p>At 200 GSM:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Virgin kraft Mullen burst: 130\u2013155 psi typical.<\/li>\n\n\n\n<li>Recycled kraft Mullen burst: 95\u2013120 psi typical.<\/li>\n\n\n\n<li>Tensile strength MD (machine direction): virgin 5,500\u20137,000 N\/m vs recycled 3,800\u20135,200 N\/m.<\/li>\n<\/ul>\n\n\n\n<p>That&#8217;s roughly a 25\u201335% strength penalty for recycled fibre at equivalent GSM. The trade-off is cost (recycled is 20\u201330% cheaper) and sustainability profile. For applications where strength is the binding constraint (heavy industrial bags, structural box outer liner), engineers often spec virgin. For corrugating medium and inner liner where strength is a function of the overall combined board, recycled wins on cost.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>How GSM Affects Cost<\/strong><\/h2>\n\n\n\n<p>Kraft paper pricing scales roughly linearly with GSM at constant fibre type and quality grade. Indicative wholesale pricing in mid-2025 (FOB mill, 5+ tonne lots):<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>60 GSM virgin kraft: $980\u2013$1,180 \/ tonne.<\/li>\n\n\n\n<li>100 GSM virgin kraft: $920\u2013$1,100 \/ tonne (slightly cheaper per tonne because higher-volume grades have better mill economics).<\/li>\n\n\n\n<li>150 GSM kraft testliner: $720\u2013$880 \/ tonne for recycled, $920\u2013$1,080 \/ tonne for virgin.<\/li>\n\n\n\n<li>200 GSM heavy testliner: $700\u2013$850 \/ tonne for recycled, $880\u2013$1,050 \/ tonne for virgin.<\/li>\n\n\n\n<li>300 GSM kraftliner outer: $920\u2013$1,100 \/ tonne for virgin.<\/li>\n<\/ul>\n\n\n\n<p>Per square metre cost is the GSM \u00d7 per-tonne cost \u00f7 1,000,000. So 100 GSM virgin at $1,000\/tonne costs $0.10\/m\u00b2. A typical retail kraft bag at 110 GSM with 0.15 m\u00b2 of paper has roughly $0.016 of paper material content.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Frequently Asked Questions<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Is higher GSM always better?<\/strong><\/h3>\n\n\n\n<p>No. Heavier paper costs more, ships heavier (driving freight cost), and stiffens \u2014 which can be a problem for applications like void fill where flexibility is desirable. Match GSM to the strength requirement; over-specifying drives cost without value.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>How do I convert GSM to pounds?<\/strong><\/h3>\n\n\n\n<p>It depends on the ream size. For kraft paper (24 \u00d7 36 inch ream basis): GSM \u00d7 0.00139 \u2248 pounds-per-500-sheet ream. So 80 GSM \u2248 49 lb basis weight, 200 GSM \u2248 137 lb. The conversion isn&#8217;t universal across paper grades \u2014 bond paper uses a different ream size \u2014 which is why GSM has become the international standard.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>What GSM should I use for an Amazon-style mailer?<\/strong><\/h3>\n\n\n\n<p>Standard kraft mailers run 80\u2013100 GSM with a tear-strip closure. Heavy items benefit from 110\u2013120 GSM. Lighter than 80 GSM tears too easily during automated sortation.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Can I get the same strength at lower GSM with virgin fibre?<\/strong><\/h3>\n\n\n\n<p>Often yes. A 90 GSM virgin kraft can match the strength of 110 GSM recycled kraft on Mullen burst. The cost trade-off depends on fibre price spread \u2014 when virgin pulp is expensive, recycled at higher GSM may still come out cheaper despite the weight.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Does GSM tell me about printability?<\/strong><\/h3>\n\n\n\n<p>Indirectly. <a href=\"https:\/\/www.researchgate.net\/figure\/Stiffness-GSM-and-thickness-test-results-of-sized-fabrics_tbl2_331705064\" target=\"_blank\" rel=\"noopener\">GSM correlates with stiffness<\/a>, which affects how the paper feeds through printers and converters. But surface treatment (uncoated, MG\/machine glazed, calendered) and brightness drive printability more than GSM. Specify both: &#8216;120 GSM MG natural kraft, brightness ISO 30%&#8217; is more useful than just &#8216;120 GSM kraft&#8217;.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>What GSM do you supply at Kangchuang?<\/strong><\/h3>\n\n\n\n<p>Kangchuang produces <a href=\"https:\/\/kangchuangpapers.com\/de\/top-kraft-paper-suppliers-ecommerce\/\">industrial kraft<\/a> from 40 GSM through 300 GSM, in virgin and recycled fibre lines, FSC chain-of-custody certified. Standard widths from 200 mm to 2,400 mm, in roll or sheet format. Typical lead time is 3\u20134 weeks door-to-door for international destinations including 5\u201310 days mill production and ocean transit.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Conclusion<\/strong><\/h2>\n\n\n\n<p>Kraft paper GSM is the primary specification that drives strength, cost, and converting performance. Light grades (40\u201380 GSM) handle food contact and light wrap; mid-range (90\u2013150 GSM) covers retail bags and mailing; heavy grades (150\u2013300 GSM) carry corrugating medium and outer liner duty. Get the GSM wrong and you either fail in service or pay too much for over-specified paper.<\/p>\n\n\n\n<p><strong>Need help specifying the right GSM for your packaging application? <\/strong>Contact Kangchuang Papers for a sample pack covering 40\u2013300 GSM industrial kraft grades, FSC certified, with lab test data on every grade.<\/p>","protected":false},"excerpt":{"rendered":"<p>Kraft paper GSM (grams per square metre) measures the basis weight of paper \u2014 heavier GSM means thicker, stronger paper. Common kraft paper ranges from 30 GSM (lightweight tissue and food wrap) through 80 GSM (standard mailing wrap) to 300+ GSM (heavy industrial liner and structural board). The right GSM depends on application: food contact [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":5337,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[32],"tags":[],"class_list":["post-5328","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"acf":[],"_links":{"self":[{"href":"https:\/\/kangchuangpapers.com\/de\/wp-json\/wp\/v2\/posts\/5328","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kangchuangpapers.com\/de\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kangchuangpapers.com\/de\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kangchuangpapers.com\/de\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/kangchuangpapers.com\/de\/wp-json\/wp\/v2\/comments?post=5328"}],"version-history":[{"count":0,"href":"https:\/\/kangchuangpapers.com\/de\/wp-json\/wp\/v2\/posts\/5328\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/kangchuangpapers.com\/de\/wp-json\/wp\/v2\/media\/5337"}],"wp:attachment":[{"href":"https:\/\/kangchuangpapers.com\/de\/wp-json\/wp\/v2\/media?parent=5328"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kangchuangpapers.com\/de\/wp-json\/wp\/v2\/categories?post=5328"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kangchuangpapers.com\/de\/wp-json\/wp\/v2\/tags?post=5328"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}