{"id":111410,"date":"2026-05-19T12:38:10","date_gmt":"2026-05-19T07:08:10","guid":{"rendered":"https:\/\/www.guvi.in\/blog\/?p=111410"},"modified":"2026-05-19T12:38:13","modified_gmt":"2026-05-19T07:08:13","slug":"lru-page-replacement-algorithm-explained","status":"publish","type":"post","link":"https:\/\/www.guvi.in\/blog\/lru-page-replacement-algorithm-explained\/","title":{"rendered":"LRU Page Replacement Algorithm Explained (2026 Guide)"},"content":{"rendered":"\n<p>An efficient way to learn the <strong>LRU Page Replacement Algorithm<\/strong> is to relate the concepts to its definition. This blog is intended to make readers feel like they are learning something smoothly without any complications.<\/p>\n\n\n\n<p>Whether you are preparing for exams, working to upgrade your programming knowledge, or simply want to experiment with the operations of creating an operating system from scratch, this guide shall keep your brain focused and lead you gently through the topic step by step.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>TL;DR Summary<\/strong><\/h2>\n\n\n\n<ul>\n<li>This blog helps you understand <strong>the LRU Page Replacement Algorithm<\/strong> in a simple way, so you can easily grasp how <strong>memory management<\/strong> works in <strong>operating systems<\/strong>.<\/li>\n<\/ul>\n\n\n\n<ul>\n<li>It gives you a clear flow from concept to example, helping you connect theory to <strong>real execution<\/strong> rather than just memorising definitions.<\/li>\n<\/ul>\n\n\n\n<ul>\n<li>It also includes a practical <strong>code example<\/strong>, making it easier to apply the concept in <strong>programming<\/strong> and <strong>exam preparation<\/strong>.<\/li>\n<\/ul>\n\n\n\n<p><\/p>\n\n\n\n<div style=\"background-color: #099f4e; border: 3px solid #110053; border-radius: 12px; padding: 18px 22px; color: #FFFFFF; font-size: 18px; font-family: Montserrat, Helvetica, sans-serif; line-height: 1.6; box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15); max-width: 750px;\">\n  <strong style=\"font-size: 22px; color: #ffffff;\">\ud83d\udca1 Did You Know?<\/strong> <br \/><br \/>\n  <span>\n    Studies on <strong style=\"color: #110053;\">cache systems<\/strong> show that many workloads can achieve around \n    <strong style=\"color: #110053;\">90% cache hit rates<\/strong> with \n    <strong style=\"color: #110053;\">LRU-based caching<\/strong>.\n  <\/span>\n<\/div>\n\n\n\n<p><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>What is the LRU Page Replacement Algorithm<\/strong><\/h2>\n\n\n\n<p>The LRU Page Replacement Algorithm is a <strong>memory management technique <\/strong>used in an<a href=\"https:\/\/www.guvi.in\/blog\/introduction-to-operating-systems\/\" target=\"_blank\" rel=\"noreferrer noopener\"> <strong>operating system (OS)<\/strong><\/a> <strong>to select which page to remove when memory becomes full<\/strong>.<\/p>\n\n\n\n<p>The <strong><em>LRU (Least Recently Used) <\/em><\/strong>method removes the least used page, helping keep the most recently and frequently used pages in memory to <strong>maintain system performance<\/strong>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong><em>Example:<\/em><\/strong><\/h3>\n\n\n\n<p>If you only have 3 book slots in your study room table and a new book arrives, but the table is full, you remove the book you haven&#8217;t touched for a very long time.<\/p>\n\n\n\n<p>Similarly, the LRU Page Replacement<a href=\"https:\/\/www.guvi.in\/blog\/what-is-an-algorithm\/\" target=\"_blank\" rel=\"noreferrer noopener\"> <strong>Algorithm<\/strong><\/a> <strong>removes the least recently used page from memory<\/strong> and keeps the most recently used page for easier access.<\/p>\n\n\n\n<p><em>Master Data Structures &amp; Algorithms with <\/em><strong><em>HCL GUVI\u2019s<\/em><\/strong><a href=\"https:\/\/www.guvi.in\/courses\/bundles\/dsa-for-programmers\/?utm_source=blog&amp;utm_medium=hyperlink&amp;utm_campaign=LRU+Page+Replacement+Algorithm+Explained+%282026+Guide%29\" target=\"_blank\" rel=\"noreferrer noopener\"><strong><em> DSA for Programmers Course<\/em><\/strong><\/a><em> and level up your problem-solving and coding logic skills.<\/em><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>How LRU Page Replacement Works<\/strong><\/h2>\n\n\n\n<p>The following points explain how the <strong>LRU Page Replacement Algorithm<\/strong> works inside the operating system.<\/p>\n\n\n\n<ul>\n<li>The process begins when the <strong>CPU<\/strong> sends a <strong>page request<\/strong> to the <strong>operating system<\/strong>.<\/li>\n<\/ul>\n\n\n\n<ul>\n<li>The system first checks whether the required page is already present in <strong>memory<\/strong>.<\/li>\n<\/ul>\n\n\n\n<ul>\n<li>If the page is already in memory, the system uses it directly for execution. After using it, the page is marked as the <strong>most recently used page<\/strong>, and the <strong>usage order<\/strong> is updated.<\/li>\n<\/ul>\n\n\n\n<ul>\n<li>If the page is not present in memory, the system then checks whether any <strong>free memory frame<\/strong> is available. If an empty frame exists, the new page is simply loaded into that free space, and the usage order is updated again.<\/li>\n<\/ul>\n\n\n\n<ul>\n<li>However, if memory is completely full, the <strong>LRU Page Replacement Algorithm<\/strong> starts its main task. The system examines all pages currently in memory and identifies the one that has been unused the <strong>longest<\/strong>. The <strong>least recently used page<\/strong> is removed from memory.<\/li>\n<\/ul>\n\n\n\n<ul>\n<li>Once the old page is removed, the new required page is loaded into the freed memory frame. After loading, the system again updates the usage order so it knows which pages were used recently and which were not.<\/li>\n<\/ul>\n\n\n\n<ul>\n<li>This same cycle keeps repeating whenever new page requests arrive. Because of this process, the operating system always tries to keep <strong>recently accessed pages<\/strong> in memory, reducing <strong>page faults<\/strong> and improving overall <strong>system performance<\/strong>.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Code Example<\/strong><\/h2>\n\n\n\n<p>function lruPageReplacement(pages, capacity) {<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;let memory = [];<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;let pageFaults = 0;<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;for (let page of pages) {<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;\/\/ Check if page already exists in memory<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if (memory.includes(page)) {<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;\/\/ Remove page from current position<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;memory.splice(memory.indexOf(page), 1);<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;\/\/ Add it to the end as the most recently used<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;memory.push(page);<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;} else {<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;pageFaults++;<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;\/\/ If memory is full, remove the least recently used page<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if (memory.length === capacity) {<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;memory.shift();<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;\/\/ Add new page<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;memory.push(page);<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;console.log(&#8220;Current Memory:&#8221;, memory);<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;}<\/p>\n\n\n\n<p>&nbsp;&nbsp;&nbsp;&nbsp;console.log(&#8220;Total Page Faults:&#8221;, pageFaults);<\/p>\n\n\n\n<p>}<\/p>\n\n\n\n<p>const pages = [1, 2, 3, 1, 4, 5];<\/p>\n\n\n\n<p>const capacity = 3;<\/p>\n\n\n\n<p>lruPageReplacement(pages, capacity);<\/p>\n\n\n\n<p><strong>Output:<\/strong><\/p>\n\n\n\n<p>Current Memory: [1]<\/p>\n\n\n\n<p>Current Memory: [1, 2]<\/p>\n\n\n\n<p>Current Memory: [1, 2, 3]<\/p>\n\n\n\n<p>Current Memory: [2, 3, 1]<\/p>\n\n\n\n<p>Current Memory: [3, 1, 4]<\/p>\n\n\n\n<p>Current Memory: [1, 4, 5]<\/p>\n\n\n\n<p>Total Page Faults: 5<br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong><em>Code Explanation:<\/em><\/strong><\/h3>\n\n\n\n<p>\u2022 The code first checks whether the required <strong>page<\/strong> is already present in the <strong>memory<\/strong>.<\/p>\n\n\n\n<p>\u2022 If the page already exists, it is marked as the <strong>most recently used page<\/strong> by moving it to the latest position.<\/p>\n\n\n\n<p>\u2022 When a new page arrives, and memory still has <strong>free space<\/strong>, the page is directly added to memory.<\/p>\n\n\n\n<p>\u2022 If the memory becomes full, the code removes the <strong>least recently used page<\/strong> from the beginning of the memory list.<\/p>\n\n\n\n<p>\u2022 After every operation, the updated <strong>memory state<\/strong> is printed so you can clearly see how the <strong>LRU Page Replacement Algorithm<\/strong> manages pages step by step.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><strong>Important Note:<\/strong><\/h4>\n\n\n\n<ul>\n<li>A <strong>page<\/strong> is a small, fixed-size block of <strong>data<\/strong> or <strong>instructions<\/strong> stored in <strong>memory<\/strong>.<\/li>\n\n\n\n<li>The <strong>operating system<\/strong> divides programs into pages so they can be loaded and managed efficiently in <strong>RAM<\/strong>.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Real-World Applications<\/strong><\/h2>\n\n\n\n<p>These are the top 5 applications of the <strong>LRU Page Replacement Algorithm:<\/strong><\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>a. Operating Systems<\/strong><\/h3>\n\n\n\n<p>Used to manage <strong>memory pages<\/strong> efficiently by removing the <strong>least recently used pages<\/strong> from <strong>RAM<\/strong>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>b. CPU Cache Management<\/strong><\/h3>\n\n\n\n<p>Helps processors keep <strong>recently accessed data<\/strong> in <strong>cache memory<\/strong> for faster execution speed.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>c. Database Systems<\/strong><\/h3>\n\n\n\n<p>Databases use <strong>LRU (least-recently used) caching<\/strong> to store <strong>frequently accessed queries<\/strong> and data for faster retrieval.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>d. Web Browsers<\/strong><\/h3>\n\n\n\n<p>Browsers use <strong>LRU (least-recently used) cache management<\/strong> to keep <strong>recently visited website data<\/strong> for faster page loading.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>e. Mobile Applications<\/strong><\/h3>\n\n\n\n<p>Apps use <strong>LRU cache management<\/strong> to handle <strong>limited device memory<\/strong> and improve <strong>performance<\/strong>.<\/p>\n\n\n\n<p>Before any great app becomes famous, someone first understands what users truly need. Learn that superpower with <strong>HCL GUVI\u2019s<\/strong><a href=\"https:\/\/www.guvi.in\/courses\/project-management\/software-requirement-rngineering\/?utm_source=blog&amp;utm_medium=hyperlink&amp;utm_campaign=LRU+Page+Replacement+Algorithm+Explained+%282026+Guide%29\" target=\"_blank\" rel=\"noreferrer noopener\"><strong> Software Requirement Engineering Course<\/strong><\/a> and start thinking like a real software engineer.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Conclusion<\/strong><\/h2>\n\n\n\n<p>The <strong>LRU Page Replacement Algorithm<\/strong> remains one of the most practical and widely adopted memory management algorithms to date, due to its simple and efficient implementation. Focusing on recently used pages helps systems maintain better performance and smarter memory utilisation in real-world computing environments.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>FAQs<\/strong><\/h2>\n\n\n<div id=\"rank-math-faq\" class=\"rank-math-block\">\n<div class=\"rank-math-list \">\n<div id=\"faq-question-1779167989663\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \"><strong>What happens if the required page is already in memory?<\/strong><\/h3>\n<div class=\"rank-math-answer \">\n\n<p>The system directly uses that page and updates its recent usage.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1779167991693\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \"><strong>Why does LRU remove old pages first?<\/strong><\/h3>\n<div class=\"rank-math-answer \">\n\n<p>Older unused pages are less likely to be needed immediately.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1779167992485\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \"><strong>What is a page fault in LRU?<\/strong><\/h3>\n<div class=\"rank-math-answer \">\n\n<p>It occurs when the required page is not found in memory.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1779168035478\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \"><strong>Why is page usage tracking important in LRU?<\/strong><\/h3>\n<div class=\"rank-math-answer \">\n\n<p>It helps the system identify which page to remove.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1779168038541\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \"><strong>What happens when memory becomes full?<\/strong><\/h3>\n<div class=\"rank-math-answer \">\n\n<p>The least-recently used page is replaced by the new page.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1779168068544\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \"><strong>Why is LRU commonly used in systems?<\/strong><\/h3>\n<div class=\"rank-math-answer \">\n\n<p>It helps improve memory efficiency and overall performance.<\/p>\n\n<\/div>\n<\/div>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>An efficient way to learn the LRU Page Replacement Algorithm is to relate the concepts to its definition. This blog is intended to make readers feel like they are learning something smoothly without any complications. Whether you are preparing for exams, working to upgrade your programming knowledge, or simply want to experiment with the operations [&hellip;]<\/p>\n","protected":false},"author":64,"featured_media":111443,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17],"tags":[],"views":"32","authorinfo":{"name":"Abhishek Pati","url":"https:\/\/www.guvi.in\/blog\/author\/abhishek-pati\/"},"thumbnailURL":"https:\/\/www.guvi.in\/blog\/wp-content\/uploads\/2026\/05\/LRU-Page-Replacement-300x116.webp","jetpack_featured_media_url":"https:\/\/www.guvi.in\/blog\/wp-content\/uploads\/2026\/05\/LRU-Page-Replacement.webp","_links":{"self":[{"href":"https:\/\/www.guvi.in\/blog\/wp-json\/wp\/v2\/posts\/111410"}],"collection":[{"href":"https:\/\/www.guvi.in\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.guvi.in\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.guvi.in\/blog\/wp-json\/wp\/v2\/users\/64"}],"replies":[{"embeddable":true,"href":"https:\/\/www.guvi.in\/blog\/wp-json\/wp\/v2\/comments?post=111410"}],"version-history":[{"count":3,"href":"https:\/\/www.guvi.in\/blog\/wp-json\/wp\/v2\/posts\/111410\/revisions"}],"predecessor-version":[{"id":111447,"href":"https:\/\/www.guvi.in\/blog\/wp-json\/wp\/v2\/posts\/111410\/revisions\/111447"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.guvi.in\/blog\/wp-json\/wp\/v2\/media\/111443"}],"wp:attachment":[{"href":"https:\/\/www.guvi.in\/blog\/wp-json\/wp\/v2\/media?parent=111410"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.guvi.in\/blog\/wp-json\/wp\/v2\/categories?post=111410"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.guvi.in\/blog\/wp-json\/wp\/v2\/tags?post=111410"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}