Ecological Footprint Calculator Formula

Understand the math behind the ecological footprint calculator. Each variable explained with a worked example.

Use the Ecological Footprint Calculator

Formulas Used

Total Ecological Footprint

total_gha = carbon_gha + food_gha + housing_gha + goods_gha

Earths Needed

earths_needed = (carbon_gha + food_gha + housing_gha + goods_gha) / 1.6

Carbon Footprint Share

carbon_share = carbon_gha / (carbon_gha + food_gha + housing_gha + goods_gha) * 100

vs World Average (2.7 gha)

vs_world_avg = (carbon_gha + food_gha + housing_gha + goods_gha) / 2.7 * 100

Variables

VariableDescriptionDefault
carbon_tonsAnnual CO2 Emissions(metric tons)12
food_factorFood Footprint Factor(gha multiplier)1.2
housing_sqftHome Size(sq ft)2000
goods_spendingMonthly Goods & Services(USD)1000
carbon_ghaDerived value= carbon_tons * 0.34calculated
food_ghaDerived value= food_factor * 0.9calculated
housing_ghaDerived value= housing_sqft * 0.0003calculated
goods_ghaDerived value= goods_spending * 12 * 0.00005calculated

How It Works

How to Calculate Your Ecological Footprint

The ecological footprint measures how much biologically productive land and sea is needed to support your lifestyle.

Formula

Total gha = Carbon gha + Food gha + Housing gha + Goods gha

Earths Needed = Your Footprint / Earth's Biocapacity per Person

Benchmarks

  • World average: 2.7 gha
  • US average: 8.1 gha
  • Earth's biocapacity: ~1.6 gha per person
  • If everyone lived like Americans, we would need 5 Earths

    • Worked Example

    An American with 12 tons CO2, moderate food, 2,000 sq ft home, $1,000/month spending.

    carbon_tons = 12food_factor = 1.2housing_sqft = 2000goods_spending = 1000
    1. 01Carbon: 12 * 0.34 = 4.08 gha
    2. 02Food: 1.2 * 0.9 = 1.08 gha
    3. 03Housing: 2,000 * 0.0003 = 0.60 gha
    4. 04Goods: 1,000 * 12 * 0.00005 = 0.60 gha
    5. 05Total: 4.08 + 1.08 + 0.60 + 0.60 = 6.36 gha
    6. 06Earths needed: 6.36 / 1.6 = 4.0 planets

    Frequently Asked Questions

    What is a global hectare?

    A global hectare (gha) is a unit representing the average biological productivity of all productive hectares on Earth. It allows comparison across different land types and countries.

    How many Earths does humanity currently use?

    Humanity currently uses about 1.75 Earths worth of resources, meaning we consume resources faster than they regenerate. Earth Overshoot Day falls in late July.

    What has the biggest impact on ecological footprint?

    Carbon emissions (energy and transport) account for about 60% of the global ecological footprint. Food production is second at about 25%. Reducing these two areas has the greatest effect.

    Ready to run the numbers?

    Open Ecological Footprint Calculator