Tree Carbon Calculator
Double the diameter, nearly six times the carbon.
Work out Tree Carbon. Double the diameter, nearly six times the carbon. Every rate is an input, not an assertion.
CO₂ stored
4.68 t
2,550 kg of biomass in a 50 cm oak
Biomass goes with diameter to roughly the power 2.5, so doubling the diameter multiplies stored carbon by nearly six. That exponent is the whole reason mature trees matter so disproportionately, and why replacing one with ten saplings does not come close for decades. Half of dry biomass is carbon, and CO₂ weighs 44/12 times carbon by mass. Those two conversions are exact; the allometry that gets you to biomass is not, and carries ±20% or more on any individual tree. This is a stock, not a flow. It says what is standing in the tree today and only while it stands — a felled and burnt tree releases it, a felled and built-with tree keeps it, and the difference is not visible in the number.
How the Tree Carbon Calculator works
Stored carbon and CO₂ in a standing tree from its diameter at breast height, using species allometry with roots included. Biomass goes with diameter to roughly the power 2.5.
Also known as: how much co2 does a tree absorb · carbon stored in a tree · do saplings replace a mature tree · tree biomass from diameter
Frequently asked questions
How much CO₂ does a tree store?
A 50 cm oak holds roughly 2 to 3 tonnes of CO₂ including roots. It scales with diameter to about the power 2.5, so size matters enormously more than count.
Do ten saplings replace one mature tree?
Not for decades. Because biomass goes with diameter to the power 2.5, one 50 cm tree holds more than dozens of 10 cm ones, and the gap takes a generation to close.
How is tree carbon calculated?
An allometric equation of the form biomass = a × diameter^b, fitted per species, plus roots as a fraction of the above-ground figure. Half of dry biomass is carbon; CO₂ is 44/12 times carbon.
Is this how much CO₂ the tree absorbs each year?
No. It is stock, not flow — what is standing in the tree today, and only while it stands. Dividing by age gives a rough lifetime average, not a current rate.
How accurate are these figures?
Reliable across a stand and rough on any one specimen — often ±20% or more, because allometric equations are fitted to particular species in particular regions.
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