How much CO2 does your website burn?
This free website carbon checker measures any page in about ten seconds and tells you its grade, its footprint per visit, and what that adds up to in a year. Built on the Sustainable Web Design model, with green hosting verified against The Green Web Foundation. No signup.
What that footprint equals in a year
We measure the page HTML plus its linked assets (0 counted on this test), check green hosting with The Green Web Foundation, and apply the Sustainable Web Design model (0.81 kWh/GB; 442 g CO2/kWh grid, 50.9 g/kWh renewable). Results are per page and vary with caching and devices. Equivalents are rough: 8.22 g per phone charge, 192 g per km in an average gas car, 21 kg absorbed per tree per year. Planet Media donates a percentage of every project to One Tree Planted.
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Show visitors the number in your footer. It links back here so they can test theirs too, and you can re-test any time to refresh it.
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One email with the fixes ranked by impact for this exact page, plus your badge embed code. No list, no follow-ups.
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Why it matters
The internet runs on electricity. Most of it still comes from fossil fuels.
Every page view spends real watts in a data center, a network, and a device. Multiply by billions of views and the web becomes one of the largest machines on the planet.
of global carbon emissions come from the internet, roughly the same as the airline industry
the median web page weighs today, about three times heavier than a decade ago
of CO2 emitted by a typical page view. Good pages stay under 0.2 g
How it works
No magic. Just measurement.
We weigh the page
Your HTML plus the images, scripts, and stylesheets it actually loads. Real transfer, not guesses.
We check the power
The Green Web Foundation database tells us whether the host runs on verified renewable energy. Their directory is the reference the whole industry uses, and it is the difference between a page that costs 442 g of CO2 per kilowatt hour and one that costs 50.9.
We do the math
The Sustainable Web Design model converts data into energy into CO2, and CO2 into your grade, from A+ to F. It is the open methodology behind most credible carbon estimates on the web, which is why this website carbon checker uses it instead of inventing its own scale.
Model constants: 0.81 kWh per GB transferred; 442 g CO2 per kWh on the standard grid, 50.9 g on renewables. Results are estimates per page view. Unlike most tools of this kind, the measurement runs on our own servers rather than a third-party API, so nothing about the pages you test leaves Planet Media.
Quick wins
How to burn less
Put your images on a diet
WebP format, right-sized, compressed. Media is usually 60 to 80 percent of a page's weight.
Fire the scripts you do not use
Every tracker, widget, and forgotten plugin bills the planet on every single visit.
Switch to green hosting
Same website, renewable grid. Under the SWD model that single move can cut emissions by up to 9x.
Load later, cache harder
Lazy-load below the fold, cache aggressively, and keep your fonts to one family.
Reading your grade
What the website carbon checker is actually telling you
A letter on its own does not mean much. Here is what each band tends to look like in practice, and what usually causes it.
Under 0.19 g per visit
A lean page: compressed images, few third-party scripts, and often green hosting. Most pages that land here were built this way on purpose. The job now is keeping it there, because page weight creeps back with every new marketing tag.
Between 0.19 and 0.49 g
The common result for a well-built site that has been running a few years. Usually one or two heavy hero images and a handful of scripts nobody has audited recently. This band is the easiest to improve: an afternoon of image work often moves it a full grade.
Above 0.49 g per visit
Something structural is heavy: uncompressed photography, a page builder loading its whole library, video that autoplays, or a host on fossil power. These pages are also slow, so the fix pays back twice, in emissions and in the visitors who no longer leave before the page appears.
The same measurement that produces your grade is what we run before every sustainable web design project, and the number we report back at the end. If your grade surprised you, get a quote and we will reply with a plan and a price to fix it, speed, SEO and conversion included.
The badge
Proud of your grade? Wear it.
Add this badge to your footer to show visitors your site runs clean. It links back here so they can test theirs too.
Check your site →
The badge is served as an image from our servers, so the grade stays accurate and the credit cannot be edited out. This is what it looks like once it is live:
FAQs
Questions, answered
What is a good website carbon score?
Under the Sustainable Web Design model, anything below 0.185 g of CO2 per view rates an A, and below 0.095 g an A+. The typical page emits around 0.8 g, so landing under 0.2 g puts you ahead of most of the web.
How accurate is this checker?
It reads your page, measures the transfer size of the assets it declares, verifies green hosting against The Green Web Foundation database, and applies the industry-standard SWD model. One honest limitation: it reads the page rather than rendering it, so assets pulled in later by JavaScript are not counted. On a conventional site the number lands close to what a browser actually downloads. On a site that builds most of its content with scripts, the real weight can be higher than shown, so treat the result as a floor rather than a ceiling.
Why did my score change between tests?
We cache each result for 24 hours, so same-day repeats return the same number. Across days, scores move when your page does: new images, added scripts, a CDN warming up, or rotating content all change the transfer weight.
Does a lighter site help my SEO too?
Yes. Page weight drives loading speed, and speed is both a Google ranking factor and a conversion factor. The same work that lowers your carbon grade improves your Core Web Vitals. That is the whole idea behind sustainable web design.
Is this website carbon checker really free?
Yes, with no signup and no limit on how many pages you test. The measurement, the grade and the badge are all free. The only thing that asks for an email is the optional full report, which adds the fixes ranked for your specific page. We built the tool because we needed it for our own client work, and running it publicly costs us almost nothing.
Can I test a competitor or a page that is not mine?
Any public URL works. Agencies use it to benchmark a prospect before a pitch, and sustainability teams use it to check vendors before signing. The checker only reads what a normal browser would download, so testing a page is no different from visiting it.
What happens to the URLs I test?
The result is cached for 24 hours so repeat tests are instant, and that is all. There is no third-party API in the loop: the whole measurement runs on Planet Media's own servers, which is unusual for tools like this and was a deliberate choice.
Lighter sites. Happier planet. Better business.
Your carbon grade is one of many things costing you customers. Tell us what you are building and we will reply with a plan and a price, or walk us through it on a 30-minute call.
