A page size calculator adds up the files on your page. So you can see the total weight. Spot the largest ones, it also helps you guess the load time. No joke.
Page Calc keeps everything private by running right in your browser. You can enter asset details, paste sizes, or import a HAR JSON file if you have one. Then, check the totals.
If you want a quick page weight check, start with the Page Calc page size calculator. And add just the files you want to include.
Page Calc isnt a tool to scan a live URL. Well It doesn’t perform Lighthouse audits, check Core Web Vitals. Run PageSpeed Insights, or track real users.
Thats exactly waht makes it useful if your problem is simple. You already know your asset sizes. Want to add them up without sharing the list online.
What Page Calc measures and what it doesn’t
Page Calc totals the sizes you give. It supports HTML, CSS, JS, Images, Fonts adn Other asset types.
It shows a total size and breaks down the data by type. Plus it flags the top three biggest files.
That’s often the quickest way to find what to check next.
Think of Page Calc as a page weight calculator. Rather than a full performance audit.
Page weight adds up all the file sizes.
Performance depends on many factors. Caching, request order, how browsers behave, server speed, and render blocking.
It also depends on what the user has allready loaded. Page Calc chooses to focus just on adding things up. Staying in the calculator lane.
The load time it shows is a simpel estimate for downloading files one.
At a time, with no parallel downloads.
This matters becuase browsers usualy fetch multiple files at once. Still, this basic estimate helps you quickly gauge load time on Slow 3G. Fast 3G, 4G, or any custom connection setting you pick.
Pick the right input method based on your assets
Remember. A page size calculator is only as good as the list of assets you add.
If you miss font files or include the same images twice, the total won’t be right. And Before you calculate, decide if youll enter a short list by hand. Paste sizes from somewhere, or import a HAR JSON file with the paid option.
| Method | Best for | Limits and cautions |
|---|---|---|
| Manual asset rows | Small pages, quick checks, and design reviews with a known file list | Free users can add up to 15 rows. Each row includes name, type, and size. |
| Pasted list of sizes | Copying one asset per line from notes, build reports, or exports | Pasted text is cut off after 200,000 characters. Well, Click “Fill rows” after pasting. |
| HAR JSON import | Use when you have a browser network export and want to work with HAR files | Requires the paid plan. HAR files over 5 MB or invalid files are rejected. |
| Budget check | Compare your total size to a KB limit before publishing or sharing | Paid plan feature giving a pass/fail result based on your target size. |
How to use the page size calculator
The proccess is simple.
What needs care is naming your files clearly.
So That way, teh list of biggest files still makes sense. After copying or exporting.
- Open Page Calc in your browser and start with the asset rows under “Assets”.
- Click “Add row” to add files manually. Also, you can enter name, type and size.
- If you already have a list, paste it into the “Paste a list. Of sizes, one asset per line” box.
- Click “Fill rows” to convert your pasted data into asset rows.
- Use “Remove duplicates” if you see repeated entries.
- Hit “Calculate” to get the total size, biggest assets, and load time estimate assuming a single download.
- Adjust “Custom Mbps” and “Latency ms” if those settings fit your needs.
- Set a “Budget limit. In KB” to check if your page size fits within limits. That option is available.
- Get your results using “Copy summary,” “Export CSV,” or “Export JSON”. If those buttons are shown.
The paid plan lets you add unlimited rows. Up to 2,000 files, has all six connection presets plus custom speeds. Latency, gives compression estimates, budget checks, CSV/JSON export, history of your last 20.
Calculations saved locally and HAR JSON import.
Add assets using rows, pasted sizes, or HAR JSON import
Manual rows work best if your handling a small batch of known files. A designer mgiht list three big images, two fonts, a CSS file. Plus a JS bundle.
A developer could note the HTML, main CSS, main JS.
A few media files from the build output.
Pasting sizes saves time when you already have a list ready.
Put one asset per line under “Paste a list of sizes, one asset.
Per line,” then click “Fill rows.” You should check the rows before calculating. Pasted lists may bring duplicates, old files, or labels that make sense elsewhere. But not in the calculator.
Using HAR JSON import works well if you have a network export. Want a HAR size calculator instead of typing every item.
Page Calc rejects invalid HAR files. And those over 5 MB.
Look So dont treat it as a place to dump every browsing session you have.
Pick a focused HAR file for the page you care about.
If you only have a handful of numbers, don’t build to much input. Just type the rows.
When you have hundreds or thousands of assets, pasting or HAR import is smarter. And But paid users still hit a row cap at 2,000 entries.
See total size, breakdown by type, and largest assets
The total size shows the combined weight of included assets.
The breakdown by type helps you see where the weight sits, in.
HTML, CSS, JS, Images, Fonts, or Ohter.
These categories are broad. But broad categories help answer the question. “What’s making this page heavy?”.
The top three largest assets often give you clear clues. Look a big image, font file, or JavaScript bundle usually explains a lot.
If images hold the heaviest files, try preparing smaller versions first. You could use the Private Bulk Image Compressor or change the format with the Private Image Converter. Then run the numbers again.
Try the asset size calculator view to separate planning from blame. A large file isn’t always bad. A hero image, downloadable file, or custom font might be a purposeful choice.
The goal is to make such choices clear. Before the page goes live.
Estimate load time but don’t treat the number as a promise
Page Calc can give you quick load time estimates. For Slow 3G, Fast 3G, and 4G connections. Paid plans add more presets plus custom Mbps and latency options.
Custom settings help when the presets don’t quite match your audience’s situation.
Note the label carefully. “Load time, estimate, single download, no parallelism.”.
That means the estimate doesn’t include parallel downloads. Honestly it’s also not a true user performance result, a lab test. Or a browser audit.
Use these estimates to compare different options. Not to promise your page will load in a specific time.
Latency can affect how slow your page feels, especially with many files loading.
Mbps mainly impacts how fast bytes transfer. I mean, Page Calc lets you adjust “Custom Mbps” and “Latency ms” when availible.
That’s enough to help you plan quickly. Wihtout pretending to fully simulate a browser.
Use compression estimates and set a KB performance budget
A performance budget helps teams decide if a page is acceptable. Page Calc’s paid plan has a budget check with a KB limit. And a pass/fail result.
Set the “Budget limit in KB” and calculate.
Then compare the page weight with your chosen limit.
Set your budget before you start negotiating the assets you want to keep.
If you set the limit after seeing the total, the budget becomes just a label, not a rule. I’d suggest one budget for the full page and. If the page keeps.
Growing, a second informal limit. On the type causing most trouble. Like Images or JS.
The paid compression estimate is just that, a estimate. And It applies to HTML, CSS, JS, SVG. Other at 30%, while fonts and images stay at 100%. Really.
Page Calc doesn’t compress, rewrite bundles, or change images.
It only estimates what the total size might look like under those assumptions.
Keep your results private, copy summaries, and export data
Page Calc runs directly in your browser. Promises “100% private” use, meaning your data never leaves your device.
And that makes it ideal for draft pages or assets before launch.
It’s also great for handling internal file names you don’t want to send to a server side calculator.
You can copy a summary as plain text for free. Paying users get CSV. JSON export options, which work better. If you need to track calculations over.
Time or attach results to tasks. These formats help keep things organized.
The tool doesn’t support spreadsheet imports, PDF exports, or other file types.
With a paid plan, your last 20 calculations are saved locally in localStorage. So That means the data stays on your browser. Not in the cloud.
If you share your computer, keep in mind that others usign the same. Browser profile might still see your history.
Page Calc also has embed code. So you can add the tool to any page.
This can help with internal checklists or documentation where the same page weight. Checks need to be done repeatedly.
Common mistakes and quick fixes
The total looks too small
That offen means some assets were left out.
Be sure to include the HTML, CSS, JS, images, fonts, and other relevant files. If the free version’s 15 row limit feels tight, try grouping only. It still answers your question or upgrade to the paid plan for more rows.
The total looks too large
Check for duplicates before changing any numbers.
If duplicates show up, use the “Remove duplicates” button, then review what’s left.
Duplicates can sneak in when you paste from a list. Then add manual rows later.
The HAR import fails
Make sure your file size and format are correct. Page Calc won’t accept HAR files over 5 MB or ones that aren’t valid. Try exporting a smaller HAR JSON file focused on your page, instead of. A long browsing session with unrelated requests.
The load time estimate feels off
It might actually be accurate. The estimate shows a single download without parallel loading. So it won’t match a browser’s waterfall chart.
Use it to compare roughly, then try other tests. If you need lab or real user preformance data.
The pasted list doesn’t include everything
Pasted text is cut off at 200,000 characters.
If your list is very large, split it up or use HAR JSON.
Import if that fits your case.
Remember too that the paid version caps asset rows at 2,000.
Frequently asked questions
What is page weight?
Page weight is the total size of all assets a page needs, like. HTML, CSS, JavaScript, images, fonts and other files.
Thnik of it as a planning figure. Not the same as a live speed score.
A lighter page isn’t always faster. But it’s usually easier to understand.
Can Page Calc scan a URL?
No.
Page Calc doesn’t crawl websites or scan pages. From a URL automatically.
You need to add rows, paste sizes, or import HAR JSON. When using the paid version.
Is Page Calc private?
Page Calc runs right. In your browser and says your data never leaves your device.
The paid feature for saved history keeps your last 20 calculations in localStorage.
That means yuor history stays tied to your browser on that device. It’s not stored online.
How accurate is the load time estimate?
The estimate gives you a rough idea, not an exact load time.
Page Calc assumes a single download with no parallel loading. But This makes it good for comparing asset lists or connection types.
Its not a Lighthouse test, Core Web Vitals check. PageSpeed Insights report, lab.
Audit, or a measurement of real user data.
Can I use a HAR file to calculate page weight?
Yes, if you have the paid plan that lets you import HAR JSON. Page Calc fills assets automatically when you paste a HAR file.
Keep in mind, invalid files or those larger than 5 MB wont be accepted.
How many assets can I add?
The free plan lets you add up to 15 asset rows. Including name, type, and size. Plus the paid plan has unlimited rows, up to 2,000.
For a quick check, 15 rows can be enough. If you list only the most importent files.
Start wiht assets you know and calculate once. Fix the largest surprises before you touch anything else.
Then check again after each change to track the total size. And the top three biggest assets.
Tihs way, your budget stays connected to the actual page you want to publish.
Try It Free: Page Calc
In-browser page size calculator for quick web performance estimates.
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