Our carbon calculation methodology
Tree-Nation’s carbon calculation methodology explains how we estimate the CO₂ captured by each tree planted through our platform.
It describes the calculation model behind our tree-level CO₂ values: how we estimate tree growth, biomass, stored carbon, and CO₂ capture over a conservative 10-year accounting period.
This methodology provides the measurement basis for the CO₂ values displayed across Tree-Nation forests, projects, company dashboards, offset purchases, and impact records.
| Traditional carbon calculations | Tree-Nation carbon calculation |
|
Offsets calculated per hectare |
Offsets calculated per tree |
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Offsets estimated over aspirational time horizons (up to 100 years) |
Offsets estimated over conservative time horizons (up to 10 years) |
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Limited species selection |
Flexible species selection |
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Limited outcome verification |
Continuous verification via remote sensing & geolocated field data |
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Large projects, only |
All project sizes |
How we calculate CO₂ offsets
Now in its fifth version, our methodology follows three key steps:
1️⃣ Calculating tree volume
For each species, we assess multiple factors—including height, trunk diameter, branch and root volume, dry mass, wood density, growth rate, climate, and lifespan—to determine a reliable average tree size.
2️⃣ The carbon equation
Dry wood consists of approximately 50% carbon, 6% hydrogen, 44% oxygen, and trace elements. Using a tree’s estimated mass, we calculate the total amount of carbon stored.
3️⃣ From carbon to CO₂ offset
To convert carbon into a CO₂ offset, we apply a standard ratio of 3.667 (the molecular weight difference between carbon and CO₂). We cap our calculations at 10 years of tree growth. Trees absorb carbon for decades beyond this window, but capping early acts as built-in insurance: we credit less than what trees actually deliver, so the number you receive stays defensible even under unfavorable conditions.
10-Year CO₂ modeling & upfront accounting
Tree-Nation’s methodology estimates how much CO₂ each tree will capture over its first 10 years—a period when growth and absorption are typically at their peak.
We credit this 10-year value upfront, at the moment the tree is planted. This allows you to see your expected environmental impact right away, while remaining transparent that:
⚠️ The carbon is not absorbed instantly — trees capture CO₂ gradually over time.
This ex-ante approach aligns with widely accepted environmental reporting practices and ensures clarity when presenting your impact to stakeholders.
Why use 10-year estimates?
- Reliable & conservative: We base our values on conservative assumptions, and cap all species’ CO₂ values to reflect only their first 10 years of growth.
- Transparent & standardized: You can compare tree impact across species and projects with confidence.
- Visible & motivating: Displaying estimated CO₂ capture helps you, and your audience, track progress, stay engaged, and celebrate milestones.
Methodology documentation
Our carbon methodology is continuously developed and refined, with clear documentation available for transparency and auditability.
You can access the latest version here: