--- title: "What is Window Load Event? Definition & Meaning" description: "The window load event fires when the entire page, including all dependent resources such as stylesheets, scripts, images, and iframes, has finished loading." lang: en json-ld: | [ { "@context": "https://schema.org", "@type": "DefinedTerm", "name": "Window Load Event", "description": "The window load event fires when the entire page, including all dependent resources such as stylesheets, scripts, images, and iframes, has finished loading.", "url": "https://www.pagespeedmatters.com/resources/glossary/window-load-event", "inDefinedTermSet": { "@type": "DefinedTermSet", "name": "Web Performance Glossary", "url": "https://www.pagespeedmatters.com/resources/glossary" } }, { "@context": "https://schema.org", "@type": "BreadcrumbList", "itemListElement": [ { "@type": "ListItem", "position": 1, "name": "Home", "item": "https://www.pagespeedmatters.com" }, { "@type": "ListItem", "position": 2, "name": "Resources", "item": 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Squarespace Speed Optimization ](/services/squarespace-speed-optimization) [Book a Call](/contact) [Home](/) [Resources](/resources) [Glossary](/resources/glossary) Window Load Event Loading Performance · Glossary # Window Load Event ![Matt Suffoletto](/assets/matt-CEkmAuBN.jpg)Written by [Matt Suffoletto](/resources/author/matt-suffoletto) Published June 26, 2026 ![Window Load Event](/__l5e/assets-v1/d185deee-ff51-4533-8bc7-0f52ca9d44f6/gloss-hero-window-load-event.png) Share [](https://twitter.com/intent/tweet?url=https%3A%2F%2Fwww.pagespeedmatters.com%2Fresources%2Fglossary%2Fwindow-load-event&text=Window%20Load%20Event)[](https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fwww.pagespeedmatters.com%2Fresources%2Fglossary%2Fwindow-load-event)[](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fwww.pagespeedmatters.com%2Fresources%2Fglossary%2Fwindow-load-event)[](https://www.reddit.com/submit?url=https%3A%2F%2Fwww.pagespeedmatters.com%2Fresources%2Fglossary%2Fwindow-load-event&title=Window%20Load%20Event) On This Page - [TL;DR](#tldr "TL;DR") - [What is Window Load Event](#definition "What is Window Load Event") - [How It's Measured](#how-measured "How It's Measured") Share this guide 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Get my audit 100% free Results in 24h ## TL;DR The window load event fires when the entire page, including all dependent resources such as stylesheets, scripts, images, and iframes, has finished loading. ## What is Window Load Event? The window load event fires when the entire page, including all dependent resources such as stylesheets, scripts, images, and iframes, has finished loading. Learn more in our [understanding load timing metrics](/resources/guides/web-performance-optimization-complete-guide) guide, or work with us through our [done-for-you speed optimization service](/services). ## How Window Load Event is Measured The event is reported by the Navigation Timing API and visible in browser developer tools. ## Related Terms [Glossary ### DOMContentLoaded (DCL) ](/resources/glossary/dom-content-loaded)[Glossary ### Fully Loaded Time ](/resources/glossary/fully-loaded-time) Sources - [MDN: Window load event](https://developer.mozilla.org/en-US/docs/Web/API/Window/load_event) [![PageSpeed Matters](/assets/logo-DtyG_mQE.png)](/) We optimize website load times to rank higher, decrease advertising costs, and convert more often. 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