{"id":6274,"date":"2026-06-02T17:57:43","date_gmt":"2026-06-02T14:57:43","guid":{"rendered":"https:\/\/karusele.com\/coliai-i-mm\/"},"modified":"2026-06-02T17:57:43","modified_gmt":"2026-06-02T14:57:43","slug":"coliai-i-mm","status":"publish","type":"page","link":"https:\/\/karusele.com\/en\/coliai-i-mm\/","title":{"rendered":"Inches to mm \u2014 converter and DN table"},"content":{"rendered":"<h1>Inches to mm \u2014 converter and DN \/ BSP reference table<\/h1>\n<p>This inches to mm converter allows you to quickly convert inches to millimeters or millimeters to inches. You will also find a DN \u2194 inch \u2194 mm reference table \u2014 ideal for selecting pipes, threads, and fittings according to standard DN (nominal diameter).<\/p>\n<div class=\"kr-calc kr-coliai\">\n<style>\n.kr-coliai .kr-conv-row{display:flex;gap:1em;align-items:flex-end;flex-wrap:wrap;margin-bottom:1em}\n.kr-coliai .kr-conv-row>div{flex:1;min-width:140px}\n.kr-conv-sep{text-align:center;font-size:1.4em;font-weight:bold;padding-bottom:.4em;color:#555}\n.kr-coliai table{width:100%;border-collapse:collapse;margin-top:1em;font-size:.88em}\n.kr-coliai table th{background:#1a73e8;color:#fff;padding:.5em .7em;text-align:left}\n.kr-coliai table td{padding:.45em .7em;border-bottom:1px solid #e5e5e5}\n.kr-coliai table tr:hover td{background:#f0f6ff}\n<\/style>\n<h3>? Inches \u2194 mm converter<\/h3>\n<div class=\"kr-conv-row\">\n  <div>\n    <label>Inches (in)\n      <input type=\"number\" id=\"kr-col-in\" step=\"0.001\" placeholder=\"e.g. 1.5\" oninput=\"krColToMm()\">\n    <\/label>\n  <\/div>\n  <div class=\"kr-conv-sep\">\u2194<\/div>\n  <div>\n    <label>Millimeters (mm)\n      <input type=\"number\" id=\"kr-col-mm\" step=\"0.01\" placeholder=\"e.g. 38.1\" oninput=\"krMmToCol()\">\n    <\/label>\n  <\/div>\n<\/div>\n<div id=\"kr-col-res\" style=\"font-size:.95em;color:#333;margin-bottom:1em;min-height:1.4em\"><\/div>\n<h4 style=\"margin:.5em 0 .3em;font-size:1em\">DN \u2194 Inch \u2194 mm reference table<\/h4>\n<table>\n<thead><tr><th>DN<\/th><th>Inch (BSP)<\/th><th>Outer \u00d8 mm<\/th><th>Inner \u00d8 mm (approx.)<\/th><\/tr><\/thead>\n<tbody>\n<tr><td>DN 6<\/td><td>1\/8\"<\/td><td>10,2<\/td><td>6,8<\/td><\/tr>\n<tr><td>DN 8<\/td><td>1\/4\"<\/td><td>13,5<\/td><td>9,2<\/td><\/tr>\n<tr><td>DN 10<\/td><td>3\/8\"<\/td><td>17,2<\/td><td>12,5<\/td><\/tr>\n<tr><td>DN 15<\/td><td>1\/2\"<\/td><td>21,3<\/td><td>15,8<\/td><\/tr>\n<tr><td>DN 20<\/td><td>3\/4\"<\/td><td>26,9<\/td><td>20,4<\/td><\/tr>\n<tr><td>DN 25<\/td><td>1\"<\/td><td>33,7<\/td><td>26,6<\/td><\/tr>\n<tr><td>DN 32<\/td><td>1 1\/4\"<\/td><td>42,4<\/td><td>35,2<\/td><\/tr>\n<tr><td>DN 40<\/td><td>1 1\/2\"<\/td><td>48,3<\/td><td>41,0<\/td><\/tr>\n<tr><td>DN 50<\/td><td>2\"<\/td><td>60,3<\/td><td>52,5<\/td><\/tr>\n<tr><td>DN 65<\/td><td>2 1\/2\"<\/td><td>76,1<\/td><td>68,0<\/td><\/tr>\n<tr><td>DN 80<\/td><td>3\"<\/td><td>88,9<\/td><td>80,9<\/td><\/tr>\n<tr><td>DN 100<\/td><td>4\"<\/td><td>114,3<\/td><td>105,3<\/td><\/tr>\n<\/tbody>\n<\/table>\n<script>\n(function(){\nfunction krColToMm(){\n  var v=parseFloat(document.getElementById('kr-col-in').value);\n  if(isNaN(v)){document.getElementById('kr-col-mm').value='';document.getElementById('kr-col-res').textContent='';return;}\n  var mm=(v*25.4).toFixed(4);\n  document.getElementById('kr-col-mm').value=mm;\n  document.getElementById('kr-col-res').textContent=v+' col. = '+mm+' mm';\n}\nfunction krMmToCol(){\n  var v=parseFloat(document.getElementById('kr-col-mm').value);\n  if(isNaN(v)){document.getElementById('kr-col-in').value='';document.getElementById('kr-col-res').textContent='';return;}\n  var col=(v\/25.4).toFixed(6);\n  document.getElementById('kr-col-in').value=col;\n  document.getElementById('kr-col-res').textContent=v+' mm = '+col+' col.';\n}\nwindow.krColToMm=krColToMm;\nwindow.krMmToCol=krMmToCol;\n})();\n<\/script>\n<\/div>\n    \n<h2>Inch to millimeter ratio<\/h2>\n<p>One inch (1\") equals exactly <strong>25.4 mm<\/strong>. This value is an international standard (ISO 31-1). Conversion formulas:<\/p>\n<ul>\n<li><strong>Inches \u2192 mm:<\/strong> mm = inches \u00d7 25.4<\/li>\n<li><strong>mm \u2192 inches:<\/strong> inches = mm \u00f7 25.4<\/li>\n<\/ul>\n<h2>DN system for pipes<\/h2>\n<p>DN (Diameter Nominal) \u2014 nominal pipe diameter according to EN ISO 6708. Important: DN does not correspond to the actual outer diameter \u2014 it is a conditional value used to select fittings, valves, and pump connections.<\/p>\n<h2>Frequently asked questions<\/h2>\n<h3>What is a 1\/2 inch pipe in millimeters?<\/h3>\n<p>The outer diameter of a 1\/2\" (DN 15) pipe according to EN standard is <strong>21.3 mm<\/strong>This is the most commonly used diameter in plumbing and heating systems.<\/p>\n<h3>What is the difference between BSP\/G and NPT threads?<\/h3>\n<p>BSP (British Standard Pipe) \/ G threads are used in Europe and Asia, while NPT (National Pipe Taper) is used in the USA and Canada. They are not compatible with each other, so it is important to correctly identify the thread type.<\/p>\n<h3>How to convert 3\/4 inch to mm?<\/h3>\n<p>3\/4\" = 0.75 \u00d7 25.4 = <strong>19.05 mm<\/strong>The outer diameter of a DN 20 pipe (equivalent to 3\/4\") is 26.9 mm.<\/p>\n<h3>Does Karusel\u0117 sell pipes according to DN?<\/h3>\n<p>Yes \u2014 our <a href=\"\/nerudijancio-plieno-vamzdis\/\">stainless steel pipes<\/a> range is described by outer diameter and wall thickness corresponding to nominal DN.<\/p>","protected":false},"excerpt":{"rendered":"<p>Coliai \u012f mm \u2014 konverteris ir DN \/ BSP referencin\u0117 lentel\u0117 \u0160is coliai \u012f mm konverteris leid\u017eia greitai perskai\u010diuoti colius milimetrais arba milimetrus coliais. Taip pat rasite DN \u2194 colis \u2194 mm referencin\u0119 lentel\u0119 \u2014 ideali\u0105 pasirenkant vamzd\u017eius, sriegius ir fittingus pagal standartin\u012f DN (nominal\u0173 skersmen\u012f). Coli\u0173 ir milimetr\u0173 santykis Vienas colis (1&#8243;) lygus lygiai [&hellip;]<\/p>\n","protected":false},"author":0,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-6274","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/karusele.com\/en\/wp-json\/wp\/v2\/pages\/6274","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/karusele.com\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/karusele.com\/en\/wp-json\/wp\/v2\/types\/page"}],"replies":[{"embeddable":true,"href":"https:\/\/karusele.com\/en\/wp-json\/wp\/v2\/comments?post=6274"}],"version-history":[{"count":0,"href":"https:\/\/karusele.com\/en\/wp-json\/wp\/v2\/pages\/6274\/revisions"}],"wp:attachment":[{"href":"https:\/\/karusele.com\/en\/wp-json\/wp\/v2\/media?parent=6274"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}