Ultra Web Hosting

Website Carbon Footprint Calculator

Estimate the annual CO2 emissions from your website and see how much you would save by running on hydroelectric power.

Your Website

Used only to label the result. Nothing is sent to a server.
Total pageviews per month from your analytics.
2024 web average is ~2.5 MB. Use average or check Chrome DevTools Network tab.
Annual CO2 on a US-Average Grid
0kg CO2e
for your traffic
US-Average Grid (442 gCO2/kWh)
Per visit0 g
Per month0 kg
Per year0 kg
Ultra / Seattle City Light (22 gCO2/kWh)
Per visit0 g
Per month0 kg
Per year0 kg
Annual Savings by Hosting on Hydroelectric Power
0 kg CO2e/yr
equivalent to 0 trees absorbing CO2 for a year
Learn About Hydroelectric Hosting →

Methodology

What the calculator measures

This calculator estimates the operational electricity demand of serving your website (data center + network transit + end-user device) and converts that demand into kilograms of CO2e emitted by your hosting region's electric grid.

Energy intensity

  • 0.5 kWh / GB transferred — conservative estimate combining data-center, network, and end-user device energy. Used by Sustainable Web Design v2 model and similar.

Grid carbon intensity

  • 442 gCO2e / kWh — US average grid intensity per EPA eGRID 2023 (most hosting customers are on this).
  • 22 gCO2e / kWh — Seattle City Light 2023 published fuel mix (90%+ hydroelectric, additional wind, low-impact certified).

The math

  • Annual data transferred = pageviews × 12 × average page weight
  • Annual energy = annual data × 0.5 kWh/GB
  • Annual CO2 = annual energy × grid carbon intensity
  • Tree equivalent: 1 tree absorbs ~21 kg CO2 per year (US Forest Service estimate)

What the calculator does not measure

  • Embodied carbon of hardware manufacturing
  • Construction and decommissioning of data centers
  • Variance in caching, CDN edge serving, or page-weight optimization between visits
  • Energy use of return visitors with cached assets (we model first-visit only, so the real number for cached returns is lower)

The numbers above are order-of-magnitude estimates suitable for understanding scale and for sustainability-report inputs. Treat results as order-of-magnitude, not precise audit data.