{"id":55892,"date":"2015-10-24T15:55:05","date_gmt":"2015-10-24T13:55:05","guid":{"rendered":"http:\/\/wpcalc.com\/?p=55892"},"modified":"2026-09-28T09:33:58","modified_gmt":"2026-09-28T06:33:58","slug":"radiation-exposure","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/converters\/radiation-exposure\/","title":{"rendered":"Radiation Exposure Converter"},"content":{"rendered":"<section class=\"not-prose calculator-box\" aria-labelledby=\"calculator-title\"><div class=\"flex items-baseline sm:items-center justify-between gap-2 sm:gap-3\"><div class=\"flex flex-col sm:flex-row sm:items-center gap-2\"><span class=\"icon icon-calculator text-primary-700! text-base! dark:text-primary-300!\" aria-hidden=\"true\"><\/span><h2 id=\"calculator-title\" class=\"text-lg font-display font-bold\">Convert Radiation Exposure Between Units<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"55892\" data-favorite-title=\"Radiation Exposure\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/converters\/radiation-exposure\/\" data-favorite-excerpt=\"Convert radiation exposure between C\/kg, mC\/kg, \u03bcC\/kg, and roentgens (R). Enter an exposure value, then select the units to convert from and to.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-physic\">\n    <span class=\"icon icon-shape-star-empty\" aria-hidden=\"true\"><\/span>\n  <\/button>\n  <div class=\"calcdash-favorite__tip\" aria-hidden=\"true\">\n   <span class=\"favorite-tooltip\" id=\"favorite-tooltip\"><\/span>\n  <\/div>\n  <span class=\"sr-only\" role=\"status\" id=\"favorite-status\"><\/span>\n<\/div><\/div><form action=\"https:\/\/wpcalc.com\/en\/converters\/radiation-exposure\/\" method=\"POST\" class=\"calculator\" id=\"calculator-55892\" data-post=\"55892\"><fieldset class=\"fieldset-input\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field is-single\" id=\"input-1\"><label for=\"field-1\">Exposure value<\/label><input type=\"text\" name=\"exposure_value\" id=\"field-1\" aria-describedby=\"calc-unit-1 calc-info-1\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"0\" value=\"1\"\/><div class=\"unit\" id=\"calc-unit-1\"><\/div><small id=\"calc-info-1\">Enter the radiation exposure value to convert<\/small><\/div><div class=\"field\" id=\"input-2\"><label for=\"field-2\">From unit<\/label><div class=\"grid grid-cols-1\"><select id=\"field-2\" name=\"from_unit\"><option value=\"C\/kg\">Coulomb per kilogram (C\/kg)<\/option><option value=\"mC\/kg\">Millicoulomb per kilogram (mC\/kg)<\/option><option value=\"\u03bcC\/kg\">Microcoulomb per kilogram (\u03bcC\/kg)<\/option><option value=\"R\">Roentgen (R)<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><div class=\"field\" id=\"input-3\"><label for=\"field-3\">To unit<\/label><div class=\"grid grid-cols-1\"><select id=\"field-3\" name=\"to_unit\"><option value=\"C\/kg\">Coulomb per kilogram (C\/kg)<\/option><option value=\"mC\/kg\">Millicoulomb per kilogram (mC\/kg)<\/option><option value=\"\u03bcC\/kg\">Microcoulomb per kilogram (\u03bcC\/kg)<\/option><option value=\"R\">Roentgen (R)<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"55892\">Calculate<\/button><button type=\"reset\">Reset<\/button><\/div><div class=\"field is-checkbox hidden!\" id=\"field-auto-calc\"><input type=\"checkbox\" id=\"auto-calc\"><label for=\"auto-calc\">Calculate automatically<\/label><small>If enabled, the result will update automatically when you change any value.<\/small><\/div><div class=\"fieldset-result is-hidden\" aria-labelledby=\"result-title\" aria-live=\"polite\" role=\"region\"> <h3 class=\"result-title bg-gradient-to-r from-primary-50 to-gray-50 dark:from-primary-900 dark:to-gray-800\" id=\"result-title\"><span class=\"icon icon-s-pulse\" aria-hidden=\"true\"><\/span> Your Results<\/h3><div class=\"result-box\"><div class=\"field-result\" id=\"output-1\"><span class=\"field-title\"><span>Converted Radiation Exposure<\/span><\/span><span class=\"field-value\" id=\"result-1\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><\/div><div class=\"result-actions\"><button type=\"button\" class=\"copy-link\"><svg viewBox=\"0 0 20 20\" fill=\"currentColor\" aria-hidden=\"true\"><path d=\"M12.232 4.232a2.5 2.5 0 0 1 3.536 3.536l-1.225 1.224a.75.75 0 0 0 1.061 1.06l1.224-1.224a4 4 0 0 0-5.656-5.656l-3 3a4 4 0 0 0 .225 5.865.75.75 0 0 0 .977-1.138 2.5 2.5 0 0 1-.142-3.667l3-3Z\"\/><path d=\"M11.603 7.963a.75.75 0 0 0-.977 1.138 2.5 2.5 0 0 1 .142 3.667l-3 3a2.5 2.5 0 0 1-3.536-3.536l1.225-1.224a.75.75 0 0 0-1.061-1.06l-1.224 1.224a4 4 0 1 0 5.656 5.656l3-3a4 4 0 0 0-.225-5.865Z\"\/><\/svg><span class=\"copy-link__text\">Copy link to this calculation<\/span><\/button><span class=\"sr-only\" role=\"status\" id=\"copy-link-status\"><\/span><\/div><\/div><a href=\"#respond\" class=\"hidden transition-opacity duration-300 opacity-0 w-50 text-sm justify-center items-center gap-2 px-4 py-2 rounded bg-gray-200 text-gray-700 hover:bg-gray-300\" id=\"leave-comment\"><span class=\"icon icon-comments\" aria-hidden=\"true\"><\/span>Leave a Comment<\/a><\/form><\/section><section id=\"calc-reactions\" class=\"not-prose hidden my-12 bg-gradient-to-r from-primary-50 to-gray-50 border border-indigo-100 rounded-xl px-6 py-4 shadow-sm\" data-post=\"55892\" aria-live=\"polite\" aria-labelledby=\"calc-reactions-title\"><p id=\"calc-reactions-title\" class=\"text-sm text-gray-500 text-center mb-2\">How did this result make you feel?<\/p><div role=\"group\" aria-labelledby=\"calc-reactions-title\" class=\"grid grid-cols-3 sm:flex sm:flex-row sm:justify-around gap-4 sm:items-center sm:flex-wrap\"><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"like\"><span class=\"reaction-count\" data-reaction-count=\"like\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude00 <\/span><span class=\"reaction-description font-medium\">Like <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"helpful\"><span class=\"reaction-count\" data-reaction-count=\"helpful\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\udca1 <\/span><span class=\"reaction-description font-medium\">Helpful <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"confused\"><span class=\"reaction-count\" data-reaction-count=\"confused\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude15 <\/span><span class=\"reaction-description font-medium\">Confused <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"disappointed\"><span class=\"reaction-count\" data-reaction-count=\"disappointed\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude1e <\/span><span class=\"reaction-description font-medium\">Disappointed <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"inaccurate\"><span class=\"reaction-count\" data-reaction-count=\"inaccurate\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\u274c <\/span><span class=\"reaction-description font-medium\">Inaccurate <\/span><\/button><\/div><div id=\"reaction-message\" class=\"hidden mt-8 rounded-md border border-primary-100 bg-white\/50 backdrop-blur-sm px-4 py-2 text-sm text-center shadow-sm\"><\/div><\/section><div class=\"calcdash-ad not-prose calcdash-ad--calc_result calcdash-ad--in-article\"><ins class=\"adsbygoogle\" style=\"display:block\" data-ad-client=\"ca-pub-1721569815777345\" data-ad-slot=\"6317458308\" data-ad-layout=\"in-article\" data-ad-format=\"fluid\"><\/ins><script>(adsbygoogle = window.adsbygoogle || []).push({});<\/script><\/div>\n<style id=\"wpcoderpro-inline-1\">.formula-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section class=\"formula-box\" aria-labelledby=\"formula-title\">\r\n\t<div id=\"formula-title\" class=\"not-prose font-display mb-4\"><span class=\"icon icon-formula\" aria-hidden=\"true\"><\/span><h2>Radiation Exposure Formula<\/h2><\/div>\r\n\t<figure class=\"not-prose formula\">\r\n\t\t<figcaption class=\"formula-title\">Formula<\/figcaption>\r\n\t\t<div class=\"text-base text-gray-800\" id=\"formula\">\n\\[X_{\\mathrm{to}}=X_{\\mathrm{from}}\\frac{k_{\\mathrm{from}}}{k_{\\mathrm{to}}}\\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(X_{\\mathrm{from}}\\) \u2014 exposure value entered in the selected From unit.<\/li>\n<li>\\(X_{\\mathrm{to}}\\) \u2014 converted exposure value in the selected To unit.<\/li>\n<li>\\(k_{\\mathrm{from}}\\) and \\(k_{\\mathrm{to}}\\) \u2014 the respective unit factors in C\/kg per unit: 1 for C\/kg, \\(10^{-3}\\) for mC\/kg, \\(10^{-6}\\) for \u03bcC\/kg, and \\(2.58\\times10^{-4}\\) for R.<\/li>\n<\/ul>\n<p>The converter first expresses the entered value in C\/kg, then divides by the factor for the requested unit. The roentgen conversion uses \\(1\\ \\mathrm{R}=2.58\\times10^{-4}\\ \\mathrm{C\/kg}\\).<\/p>\n<p>\r\n<\/section>\n<style id=\"wpcoderpro-inline-459\">.calculation-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section id=\"calculation\" class=\"calculation-box\" aria-labelledby=\"calculation-title\">\r\n\t<div id=\"calculation-title\" class=\"not-prose font-display\"><span class=\"icon icon-unordered-list\" aria-hidden=\"true\"><\/span><h2>Radiation Exposure \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> use the default settings to convert an exposure of 1 C\/kg to roentgens.<\/p>\n<p>\\[X_{\\mathrm R}=1\\ \\mathrm{C\/kg}\\times\\frac{1\\ \\mathrm R}{2.58\\times10^{-4}\\ \\mathrm{C\/kg}}=3875.96899225\\ \\mathrm R\\]<\/p>\n<p><strong>Result:<\/strong> 1 C\/kg is approximately 3,875.96899225 R, as displayed to eight decimal places.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to use the calculator<\/h2>\n<ol>\n<li>Enter a nonnegative number in <strong>Exposure value<\/strong>. The default is 1.<\/li>\n<li>Choose the unit of that number in <strong>From unit<\/strong>: C\/kg, mC\/kg, \u03bcC\/kg, or R.<\/li>\n<li>Choose the unit you need in <strong>To unit<\/strong>. You can select any of the same four units.<\/li>\n<li>Read <strong>Converted Radiation Exposure<\/strong>. The result includes the selected destination unit.<\/li>\n<\/ol>\n<p>For example, to convert 1 R to SI units, enter 1, select R under <strong>From unit<\/strong>, and select C\/kg under <strong>To unit<\/strong>. The result is 0.000258 C\/kg. Selecting the same unit in both fields leaves the numerical value unchanged.<\/p>\n<h2>What radiation exposure measures<\/h2>\n<p>Radiation exposure measures the electric charge produced by ionization in air, per unit mass of air. In this specific sense, it describes the effect of X-rays or gamma rays in air\u2014not a person\u2019s overall contact with radiation. Its SI unit is the coulomb per kilogram (C\/kg); the roentgen (R) is an older unit still encountered in some instruments, records, and reference material.<\/p>\n<p>The distinction matters when comparing readings or transcribing older measurements. A value of 1 R corresponds to 0.000258 C\/kg, or 258 \u03bcC\/kg. A larger number after conversion does not indicate a larger exposure: the physical quantity stays the same while the size of the unit changes. For instance, 1 C\/kg becomes about 3,875.97 R because one roentgen is much smaller than one C\/kg.<\/p>\n<p>Exposure is not the same as absorbed dose in grays (Gy) or equivalent or effective dose in sieverts (Sv). Those quantities address energy deposited in material and, for sieverts, biological weighting. This converter changes exposure units only; it cannot determine tissue dose, health risk, or a safe exposure time from an air-exposure reading.<\/p>\n<h2>Units and practical limits<\/h2>\n<p>The converter supports milliecoulombs per kilogram and microcoulombs per kilogram as decimal multiples of C\/kg. It does <em>not<\/em> provide milliroentgens (mR), despite that unit appearing in some radiation reports. To use a reading given in mR, first divide it by 1,000 to express it in R, then enter the result with R selected as <strong>From unit<\/strong>.<\/p>\n<table>\n<thead>\n<tr>\n<th>Unit<\/th>\n<th>Equivalent in C\/kg<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>1 C\/kg<\/td>\n<td>1 C\/kg<\/td>\n<\/tr>\n<tr>\n<td>1 mC\/kg<\/td>\n<td>0.001 C\/kg<\/td>\n<\/tr>\n<tr>\n<td>1 \u03bcC\/kg<\/td>\n<td>0.000001 C\/kg<\/td>\n<\/tr>\n<tr>\n<td>1 R<\/td>\n<td>0.000258 C\/kg<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Check the original unit before entering a measurement, particularly whether it is R or mR, or whether a prefix such as milli- or micro- is present. A misplaced prefix changes the entered exposure by a factor of 1,000. The calculator accepts nonnegative values and rounds the displayed result to eight decimal places; a very small nonzero result may therefore display as zero. For calculations that depend on more precision, retain the original value and apply the conversion factors directly.<\/p>\n<p>The coulomb also appears in electrical measurements, but charge per kilogram of air is a different quantity from <a href=\"https:\/\/wpcalc.com\/en\/converters\/electric-current\/\">electric current<\/a>. Likewise, a photon\u2019s <a href=\"https:\/\/wpcalc.com\/en\/converters\/frequency\/\">frequency<\/a> is not a radiation exposure reading; converting frequency units does not establish exposure or dose.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Convert radiation exposure between C\/kg, mC\/kg, \u03bcC\/kg, and roentgens (R). Enter an exposure value, then select the units to convert from and to.<\/p>\n","protected":false},"author":70,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[3],"tags":[34],"class_list":["post-55892","post","type-post","status-publish","format-standard","hentry","category-converters","tag-physics-units"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/55892","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/users\/70"}],"replies":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/comments?post=55892"}],"version-history":[{"count":2,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/55892\/revisions"}],"predecessor-version":[{"id":65306,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/55892\/revisions\/65306"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=55892"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=55892"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=55892"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}