Tree Carbon Sequestration Calculator

On average, a mature tree absorbs roughly 21–25 kg (about 48 lbs) of CO₂ per year, though this varies significantly by species, age, size, and health. Fast-growing conifers like Douglas Fir can absorb more in their early decades, while slow-growing hardwoods may store more carbon per unit of wood due to higher wood density. This calculator uses species-specific rates to give you a more realistic estimate.

The calculator estimates the cumulative CO₂ absorbed by your trees from planting to their current age, their current annual absorption rate, and a projection of future sequestration over your chosen project lifetime. It also converts those figures into relatable equivalents like cars taken off the road or gallons of gasoline offset.

The calculation uses species-specific annual CO₂ absorption rates (kg CO₂ per tree per year) adjusted for tree age and condition. Younger trees absorb carbon more slowly; absorption peaks at mid-maturity and gradually levels off. Total lifetime CO₂ is the integral of the annual rate over the tree's age. Carbon stored (in kg C) is derived from CO₂ using the molecular weight ratio (C/CO₂ ≈ 0.2727).

Species differ in growth rate, wood density, canopy size, and lifespan — all of which affect how much biomass (and therefore carbon) they accumulate. Dense hardwoods like Black Walnut lock away more carbon per unit of volume, while fast-growing softwoods like Douglas Fir may sequester more carbon quickly due to rapid early growth. Both strategies contribute meaningfully to climate mitigation.

Trees absorb carbon most rapidly during their active growth phase — typically between ages 5 and 50, depending on species. Very young trees have limited leaf area and biomass, so their uptake is modest. As trees mature, absorption rates can slow but the cumulative carbon stored in the wood, roots, and soil continues to grow. Old-growth trees can remain significant carbon sinks for centuries.

Yes — simply enter the number of trees in your project and set the project lifetime to match your planning horizon. The calculator will show you total projected CO₂ sequestration for the whole stand. For large-scale projects, you may also want to account for tree mortality rates, which this tool does not model directly.

This tool provides educational estimates based on published average sequestration rates. For verified carbon credits or offsets (e.g., under Verra, Gold Standard, or government programs), you'll need a formal methodology, site measurements, and third-party verification. Use these results as a planning guide, not a certified offset claim.

This calculator focuses on above-ground biomass carbon sequestration, which is the most commonly referenced figure for tree planting projects. Trees also store carbon in roots and contribute to soil organic carbon over time, which can add 20–30% more to the total ecosystem carbon stock — but those figures vary widely by soil type and climate, so they are not included here.