Add up the total weight of a web page by resource type, see a visual breakdown, and estimate how long it takes to load on different connections. Enter sizes or paste code to measure it automatically. 100% in your browser — nothing is uploaded or stored.
Estimates assume full download at the connection's typical throughput; real load times also depend on latency, server speed, caching and how resources are loaded.
🔒 Everything runs in your browser. Your input is never uploaded, logged or stored.
The Page Size / Weight Calculator adds up the total weight of a web page from its parts — HTML, CSS, JavaScript, images, fonts and anything else — and shows you a clear breakdown of where the bytes go. It then estimates how long that page takes to download on slow 3G, fast 3G, 4G and broadband, and gives a plain-English verdict against a sensible performance budget, so you can see at a glance whether a page is lean or bloated.
It is part of the Performance & Code Tools group in our free SEO Toolkit. Pair it with the HTML Minifier, CSS Minifier and JavaScript Minifier to trim code weight, the Image Size Estimator to plan image budgets, and the Critical CSS Extractor to speed up first paint. Everything runs in your browser — your input is never uploaded or stored.
Understand and budget your page weight.
A colour bar shows the share of each resource type at a glance.
See download times on slow 3G, fast 3G, 4G and broadband.
A plain-English rating from excellent to bloated.
Drop in HTML, CSS or JS and it measures the size for you.
Enter sizes, read the breakdown, act.
Type each resource size, or paste code to measure.
Get the combined page weight instantly.
Compare across connection speeds.
Target the biggest segments first.
Where the weight usually lives on a real page.
Page weight is the total number of bytes a browser must download to display a page — the combined size of the HTML, stylesheets, scripts, images, fonts and any other files. The heavier a page, the longer it takes to load, especially on mobile connections, and the more it can hurt user experience and Core Web Vitals. This calculator adds up those parts, shows where the weight sits, and estimates load times. It is part of the Performance & Code Tools group.
A performance budget is a self-imposed limit on page weight that keeps a site fast. There is no single correct number, but these rough bands are a useful guide, and they are what this tool uses for its verdict.
| Total weight | Rating |
|---|---|
| Up to 500 KB | Excellent — very lean |
| 500 KB to 1 MB | Good — a common target |
| 1 MB to 2 MB | Heavy — trim where you can |
| 2 MB to 4 MB | Very heavy — slow on mobile |
| Over 4 MB | Bloated — likely poor load times |
Usually the largest part; compress and right-size them first.
Heavy scripts also cost parsing time, not just download.
Multiple weights and styles add up quickly.
Unused framework styles inflate stylesheets.
They are first-order estimates based on dividing the total bytes by each connection's typical throughput. Real load times also depend on latency, how many requests are made, server response time, compression, caching and whether resources load in parallel or block rendering. Treat the figures as a guide for comparison, not an exact measurement.
Browsers block one website from reading the contents and sizes of another website's resources for security reasons, so a fully client-side tool cannot crawl a live URL without a server in the middle. Instead, you enter the sizes, which you can read from your browser's developer tools Network tab, or paste code to have it measured here.
For the most realistic figure, use the transferred sizes shown in your developer tools, which reflect gzip or Brotli compression. The paste-to-measure feature reports the raw, uncompressed size of the text, which is useful for comparing before and after minifying but will be larger than the compressed bytes sent over the network.
No. All calculation happens locally in your browser with JavaScript, and the tool never makes a network request. Nothing you type or paste is uploaded, logged or stored, so it is safe for internal projects and confidential work.
Quantify page weight and find the worst offenders.
Set and check a performance budget for a project.
Compare weight before and after optimising.
See how resource types contribute to load time.
Use the Page Size Calculator with these tools from the SEO Toolkit: trim markup with the HTML Minifier, shrink stylesheets with the CSS Minifier, compress scripts with the JavaScript Minifier, plan image weight with the Image Size Estimator, embed tiny images with the Base64 Image Encoder, and speed up first paint with the Critical CSS Extractor.
Anyone who cares about how fast a page loads.
Everything about page weight.
It adds up the total weight of a web page from its resource types — HTML, CSS, JavaScript, images, fonts and other — shows a visual breakdown of where the bytes go, estimates download time on several connection speeds, and gives a plain-English verdict against a performance budget.
Yes, completely. There is no cost, no sign-up and no limit on how many pages you calculate. The tool runs entirely in your browser, so there are no server costs and nothing to pay for.
Open your browser's developer tools and go to the Network tab, then reload the page. It lists every request with its transferred size, and a summary of the total. Group the rows by type to get the figures for HTML, CSS, JavaScript, images and fonts to enter here.
Browsers block one site from reading another site's resources and their sizes for security reasons, so a purely client-side tool cannot crawl a live page without a server. Instead you enter the sizes from your developer tools, or paste code to have it measured locally and privately.
They are first-order estimates that divide total bytes by each connection's typical throughput. Real load times also depend on latency, the number of requests, server speed, compression, caching and how resources load. Use the figures to compare options, not as an exact measurement.
There is no universal number, but many teams target around 1 MB or less for a fast experience, and under 500 KB is excellent. Pages above 2 MB tend to feel slow on mobile. The right budget depends on your audience, their devices and their typical connection speed.
For realism, use the transferred sizes from your developer tools, which include gzip or Brotli compression. The paste-to-measure feature reports the raw uncompressed size, which is handy for before-and-after comparisons when minifying but is larger than what is actually sent over the network.
Yes. All calculation happens locally in your browser, and the tool never makes a network request. Nothing you type or paste is uploaded, logged or stored, so it is safe for internal projects, staging sites and confidential client work.
On most pages, images are by far the largest contributor, followed by JavaScript. That is why optimising images — compressing, resizing and using modern formats — and trimming scripts usually gives the biggest reduction in total page weight and the fastest improvement in load time.
Yes. Paste HTML, CSS or JavaScript into the measure box and click the matching button, and the tool fills in that row with the measured size in kilobytes. This is useful for checking the weight of a specific file or comparing a snippet before and after minifying.
Yes. The calculator is fully responsive, so you can budget page weight from a phone or tablet. Entering sizes, pasting code to measure, reading the breakdown and checking the load-time estimates all work the same as on desktop.
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Add up your page size, see where the bytes go, and estimate load times across connections — free, private and instant in your browser.
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