How to Calculate Website Carbon
What is Website Carbon?
A website carbon calculator estimates the CO2 emissions generated by a web page per visit, based on data transferred. The internet accounts for approximately 3.7% of global carbon emissions.
Formula
CO2 (g) = page_bytes × 0.81 (estimate based on typical energy grid)
- MB
- Page size (MB) — Total data transferred (HTML, CSS, JS, images)
- g_CO2
- CO2 emissions (grams) — Approximate carbon footprint per page view
Step-by-Step Guide
- 1CO2 estimate = page size (KB) × 0.06g CO2/KB
- 2This accounts for data centre energy, network, and device power
- 3Annual emissions = CO2 per view × annual page views
- 4Green hosting can reduce emissions by 50–80%
Worked Examples
Input
500KB page, 10,000 views/month
Result
~30g CO2/month = 0.36kg/year
Input
3MB heavy page, 100,000 views
Result
~180g CO2 per 100K views
Input
Lean 100KB page
Result
~6g CO2 per 1,000 views
Frequently Asked Questions
How is website carbon calculated?
Data transfer → electricity used → carbon emissions. Varies by grid mix (coal-heavy = more carbon; renewable = less).
What is a typical page carbon footprint?
Small page (1 MB): ~0.8 g CO2. Heavy page (5 MB): ~4 g CO2. A website with 100K monthly views: 80–400 kg CO2/month.
How can I reduce website carbon?
Optimize images, minify code, use efficient hosting, enable caching, serve from CDNs with renewable energy.
Ready to calculate? Try the free Website Carbon Calculator
Try it yourself →