Estimates how much CO2 a number of trees absorb over a given number of years, using a commonly cited average absorption rate.
How it works
The number of trees is multiplied by the CO2 absorption rate per tree per year and by the number of years.
What this does not include
This uses a rough average figure — actual sequestration varies enormously by tree species, age, climate, and growing conditions, so treat the result as a rough estimate rather than a precise measurement.
How to use this calculator
- Enter the number of trees, the absorption rate per tree (a common average is pre-filled), and the number of years.
A worked example
10 trees sequestering 21.77 kg CO2 each per year, over 1 year: total = 217.7 kg CO2.
5 trees at the same rate, over 2 years: total is also 217.7 kg CO2 — half as many trees over twice the time lands on the identical total.
What the variables mean
| Variable | Meaning |
|---|---|
| Trees | Number of trees |
| Rate per tree | Estimated CO2 sequestered per tree per year |
| Years | Time period being measured |
Edge cases worth knowing
Tree count and years are interchangeable multipliers in this formula — the two examples above show that half the trees over double the time produces an identical total, since both are just linear scaling factors on the same per-tree rate.
The sequestration rate is an average estimate, not a precise measurement — actual CO2 uptake varies significantly by tree species, age, and growing conditions.
Frequently asked questions
Why does absorption rate vary so much by tree age?
Young, small trees absorb relatively little CO2, while mature trees with larger canopies and more woody biomass absorb substantially more each year.
Where does the default 21.77 kg figure come from?
It’s the metric equivalent of the commonly cited “about 48 pounds per year” figure used by organizations like the Arbor Day Foundation for a maturing urban tree.
Is planting trees a complete solution to carbon emissions?
Tree planting is one part of broader carbon-reduction efforts, but reforestation alone cannot offset all emissions from human activity at current scales — it’s most effective alongside emissions reduction.
