Our free Page Speed Estimator provides a professional, high-performance solution to estimate your mobile and desktop page speed performance score, simulate page sizes, assets count, caching, and CDNs offline, 100% private directly within your browser. Engineered for maximum speed and absolute privacy, the tool operates entirely on the client side using secure local JavaScript processing—meaning your data never leaves your device and is never uploaded to any external server. Whether you are working on a desktop, tablet, or mobile phone, the responsive and premium interface delivers instant real-time results with zero wait times. Designed for daily productivity, it features fully configurable parameters, robust input verification, and offline capability to ensure a seamless, secure workflow.
Type in your page's CSS, JS, and offscreen image asset payload sizes in KB or MB.
Toggle performance optimizations such as browser caching, lazy-loading, and CDN support.
Instantly estimate your Lighthouse-grade Speed Index performance and follow diagnostic advice.
Estimates page load times based on total asset payload size, HTTP requests, and network connection speeds.
Calculate web performance budgets and identify payload compression opportunities to boost page speed.
Estimate loading speed budgets locally with 100% privacy. No site URLs or asset sizes are recorded.
A Page Speed Estimator models website load times across Mobile 4G (1.6 Mbps) and Desktop broadband (32 Mbps) connections based on asset payload budgets (JavaScript, CSS, images).
Heavy JavaScript bundles (>300 KB) block browser main-thread parsing, directly delaying Largest Contentful Paint (LCP) and degrading user experience metrics.
Enabling browser caching headers, Content Delivery Networks (CDNs), and offscreen image lazy loading yields instant performance score improvements (90-100 green grade).