Why our Website Carbon Calculator Matters: A Response to the Critics

In recent years, a growing number of voices in the tech sustainability space have raised concerns about the accuracy and usefulness of website carbon calculators. They argue that current models rely on proxy metrics like page weight, which oversimplify complex digital systems and may mislead users into thinking they have more (or less) impact than they actually do.

And they’re not wrong. These tools are not perfect.

But that doesn’t mean they’re not useful.

At Climate Logic, we built CLEAR—the Carbon Load & Emissions Audit Report—to help website owners get visibility into their digital footprint. We’re aware of the limitations in current carbon modelling. In fact, we’ve read the same critiques. But we believe that measurable imperfection is better than unmeasurable inaction. Here’s why.

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The Case Against Website Carbon Calculators

To be fair, the critiques deserve attention. Thoughtful voices like Matt Zeunert at DebugBear argue that:

• Page weight is a poor proxy for actual emissions since it doesn’t correlate well with CPU load or energy use.
• Server processing and user device power consumption vary widely and are hard to attribute to individual sites.
• Network infrastructure is always on, so emissions don’t scale directly with traffic or data transferred.
• The metrics used in carbon calculators are based on averages and assumptions that don’t always reflect the real world.

All true.

But here’s the key point: CLEAR is not pretending to be an emissions accounting tool. It’s a directional sustainability signal.

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What CLEAR Actually Measures

CLEAR takes publicly available, standardised metrics—like page size, load speed, and hosting status—and uses reputable models (like the Sustainable Web Design model and Green Web Foundation data) to generate a transparent, comparable estimate of your site’s carbon impact.

It shows:

• Estimated CO₂ per page load
• Whether your site is using green hosting
• Desktop and mobile performance scores
• Total estimated yearly emissions based on your traffic
• Visual equivalents (e.g., how many cups of tea or flat whites your emissions equal)

These figures are estimates, not gospel. But they are grounded in real-world data and reputable research.

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Why Relative Benchmarks Matter

We agree: carbon calculators can’t precisely quantify your website’s emissions. But that’s not the point.

The value lies in comparison:

• Is your homepage emitting more carbon than it should for its size?
• Are you using green hosting, or still relying on fossil-powered servers?
• How does your site stack up against others in your sector?

In other words, CLEAR doesn’t claim to be a lab-grade emissions monitor. It’s a diagnostic check-up—a way to surface inefficiencies, spot red flags, and spark conversations around digital sustainability.

Think of it like a BMI calculator for your website. It’s not perfect. But it gives you enough signal to take meaningful action.

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It’s Better Than Doing Nothing

Sustainability professionals, digital teams, and business leaders all need starting points. CLEAR gives them just that.

It’s:

• Simple to use
• Free and instant
• Visually intuitive
• Based on established models and published research

And it’s helping our clients take action—whether that’s switching to green hosting, compressing bloated assets, or simply starting a conversation at the board level about Net Zero strategies for digital infrastructure.

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What We’re Not Saying

We’re not saying that every byte transferred equals a fixed amount of carbon.
We’re not saying that running CLEAR replaces lifecycle assessments or cloud-provider carbon tools.
We’re not saying your website is single-handedly warming the planet.

We are saying that awareness, transparency, and progress start with measurement. And CLEAR delivers that—clearly.

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Want to Know Your Website’s Impact?

Try CLEAR today and get your Carbon Load & Emissions Audit Report in seconds.
It’s free, fast, and eye-opening.

Run your website through CLEAR now
Or call us on (03) 9000 0354 to discuss our Website Emissions Reduction Program.