akar.earthARR Carbon Estimator
Free ARR carbon estimator: get an indicative tCO2e range for a tree-planting project in Indonesia from area, species group, years, survival and deductions.
The ARR carbon estimator gives an indicative figure for the CO2 a tree-planting project could remove, before and after deductions, from five inputs: area, species group, years, survival and deduction rate. It is a first screen for afforestation, reforestation and revegetation ideas in Indonesia, not a credit forecast.
Method
For each species group the calculator takes a mean annual volume increment (m³/ha/yr) and a wood density, multiplies them to get stem biomass, and applies a biomass expansion factor (BEF) of 1.3 to add branches and leaves. For mangroves it uses a direct above-ground biomass increment. It then adds roots with a root-to-shoot ratio of 0.24 (0.49 for mangroves), converts biomass to carbon with a carbon fraction of 0.47, and converts carbon to CO2 with the ratio 44/12.
Gross removals = annual biomass × (1 + root ratio) × 0.47 × 44/12 × area × years × survival. Net = gross × (1 − deductions).
Assumptions
- Growth is linear: the same increment every year.
- One species group covers the whole area.
- Survival and stocking apply as a single percentage.
- Baseline removals are zero, and no leakage is counted beyond the deduction you enter.
- No harvest, thinning, fire or other losses.
Limitations
Real trees grow slowly at first, then faster, then level off, so linear growth overstates early years and may misstate later ones. Increments vary widely between sites, soils and management. The species defaults are rough planning figures, not measured values. Methodologies such as VM0047 set their own baselines, uncertainty rules and buffer contributions, which can change the net figure substantially.
How to read the result
Treat the net figure as a ballpark to compare options, such as a fast-growing species against mixed agroforestry, or 100 ha against 1,000 ha. If the number looks too small to cover project costs, see ARR project costs before going further. If it looks promising, the next step is a proper ex-ante estimate with growth curves, site data and the methodology’s deductions, which is what our carbon modelling service and the AKAR Carbon Simulator provide. For background, see the ARR hub, and for a single tree use the tree CO2 calculator.
Frequently asked questions
How accurate is this ARR carbon estimator?
It gives an order-of-magnitude figure only. Real projects can differ widely because growth is not linear, survival varies by site, and methodologies apply their own baselines and deductions.
Why are deductions set at 25% by default?
Buffer contributions and uncertainty deductions together often remove a significant share of gross removals. 25% is a placeholder; the real figure depends on the methodology, risk assessment and data quality.
Can I use the result in a PDD or sales pitch?
No. Use it to decide whether a project is worth studying. PDDs and buyer discussions need a documented ex-ante model built on site data and the chosen methodology.