How to Calculate CO₂ Storage for Urban Trees
Tree diameter is all you need. Here's how BHD feeds the carbon formula — and how to get the number in seconds on your iPhone.
Every tree in your survey stores carbon. But how much? And how do you put a number on it for a client report?
The answer starts with one measurement: breast height diameter (BHD) — the trunk diameter at 130cm above the ground. From BHD, species, and a set of peer-reviewed allometric equations, you can calculate total CO₂ stored, annual sequestration rate, and economic value per tree.
With Treesable, this calculation happens automatically the moment you save a diameter measurement — no tables, no spreadsheets.
See it in action
Eco-benefit output in Treesable — CO₂, O₂, water, and economic value
Why BHD is the key input
Above-ground biomass — the dry weight of trunk, branches, and twigs — correlates strongly with trunk diameter. Researchers have spent decades building allometric equations that map BHD to biomass for hundreds of species. Once you have biomass, converting to CO₂ is straightforward: approximately 50% of dry biomass is carbon, and each kilogram of carbon equals 3.67 kg of CO₂.
The formula in simplified form:
Where biomass is derived from a species-specific allometric equation using BHD as the primary variable.
The methodology behind the numbers
Treesable uses allometric equations sourced from peer-reviewed forestry research and aligned with the i-Tree methodology — the same framework used by urban foresters globally, including the US Forest Service and local authorities across Europe.
Key factors that affect the CO₂ calculation:
Species
Wood density and growth form vary significantly. A beech stores more carbon per cm BHD than a birch of the same diameter.
Diameter (BHD)
Carbon storage scales non-linearly with diameter — a tree with twice the BHD stores far more than twice the carbon.
Above-ground vs. total biomass
Treesable calculates above-ground biomass. Root biomass (typically 20–30% of above-ground) is not included in the displayed figure.
How to get the CO₂ figure in Treesable
Measure BHD with the AR tool
Open Treesable and use the AR BHD measurement tool to measure trunk diameter at 130cm. The measurement is saved with GPS coordinates automatically. See our guide on AR tree diameter measurement for a full walkthrough.
Confirm species identification
Tap AI Species ID and photograph the tree — leaves, bark, or canopy. Treesable returns a species match. Confirm or adjust manually. Species is required for the allometric equation to run.
View eco-benefit output
Once BHD and species are saved, Treesable instantly displays: CO₂ stored (kg), annual CO₂ sequestration (kg/year), annual O₂ production (kg/year), annual water interception (litres), and economic value (DKK/EUR).
Use the data in your report
Export your tree inventory with all eco-benefit values attached. Each entry is GPS-tagged, timestamped, and species-confirmed — ready to paste into a client report or municipality submission.
Example: a mature beech at 42cm BHD
A common European beech (Fagus sylvatica) with a BHD of 42cm — typical for a 60–80 year old street tree — stores approximately:
~1,850 kg
CO₂ stored
~22 kg/yr
Annual CO₂ sequestration
~116 kg/yr
O₂ produced annually
~12,400 L/yr
Water intercepted
These figures are illustrative. Actual values vary by local climate, soil conditions, and the specific allometric model applied. Treesable draws from the GlobAllomeTree database and incorporates local meteorological data to make calculations as accurate as possible for your location.
Note til danske arborister (kulstoflagring i bytræer)
CO₂-beregningerne i Treesable er baseret på alometriske ligninger fra peer-reviewed forskning og tilpasset nordeuropæiske træarter. Resultaterne er udtrykt i kg CO₂-ækvivalenter og kan anvendes direkte i klima- og bæredygtighedsrapporter til kommuner og private kunder. Bemærk at rodsystemets kulstoflagring ikke er inkluderet i standardberegningen.
This note is in Danish for Danish-speaking professionals.
Frequently asked questions
How accurate is the CO₂ calculation?
Allometric equations have an inherent margin of error — typically ±10–20% depending on species and local conditions. Treesable's figures are suitable for professional reporting and client communications, not laboratory-grade carbon accounting.
Which species does Treesable support?
Treesable is not limited to Northern European species. The eco-benefit engine uses the GlobAllomeTree database — a global allometric dataset covering species across multiple continents — combined with local meteorological data to improve accuracy for your specific location. This makes the calculations relevant whether you're surveying urban trees in Denmark, the UK, USA, Australia, Temperate Region or further afield.
Can I use Treesable's output in a municipal climate report?
Yes. Treesable produces GPS-tagged, species-confirmed, timestamped records with eco-benefit values that are suitable for inclusion in urban greening strategies, municipal tree inventories, and client sustainability reports.
Does Treesable calculate root carbon storage?
No. Treesable calculates above-ground biomass and CO₂ storage. Root biomass is typically estimated at 20–30% of above-ground biomass and is not included in the displayed figure.
Try it yourself
Calculate CO₂ for every tree in your next survey.
Free early access via TestFlight. iOS 17+ required.
Download on TestFlight →