Starlight Tools

Reforestation Carbon Calculator: Estimate CO₂ Sequestration

Estimate annual and cumulative CO₂ removal from a tree-planting or reforestation project. Start with tree count, land area, or an annual CO₂ target, then adjust forest type, survival, planting schedule, and project duration.

Project inputs

Example loaded: 1,000 trees in a temperate oceanic restoration project.

🌳 Project scale and schedule

🌱 Forest type

Advanced assumptions

Local forest inventory, yield tables, and monitored survival should override these broad defaults.

Included pool: simplified above-ground woody biomass growth only. Soil, below-ground biomass, litter, dead wood, harvested wood products, and project emissions are omitted.

CO₂ sequestration results

Compare saved scenarios

Save up to three calculated setups to compare planting schedules, forest types, or risk assumptions.

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How to use this reforestation carbon calculator

  1. Choose trees, land area, or a net annual removal target as the starting point.
  2. Select one-time or staggered planting and enter the project duration.
  3. Choose the closest broad forest preset, then replace defaults with local stocking, growth, and survival data where available.
  4. Review the explicit mortality, baseline, leakage, and permanence deductions.
  5. Calculate, inspect any year, export the timeline, or save the scenario for comparison.

The calculator treats every planting year as a separate cohort. Gross above-ground removal follows an establishment-plus-ramp curve; mortality then changes annually with cohort age. Baseline/additionality, leakage, and permanence are sequential planning deductions, shown separately from gross biological removal. These percentages are user assumptions, not a substitute for a project methodology.

Formula and methodology

For cohort c in project year y, age is a = y − start(c) + 1. Units are hectares, trees, years, and tonnes of CO₂.

Gross(c,y) = cohort area × full-stock tCO₂/ha/yr × growth multiplier(age)
Survival(age) = (1 − early mortality)min(age,5) × (1 − later mortality)max(age−5,0)
Net(c,y) = Gross × Survival × (1 − baseline) × (1 − leakage) × (1 − permanence buffer)
Cumulative net(y) = Σ annual net from year 1 through y
Area (ha) = trees ÷ trees/ha; density from square spacing = 10,000 ÷ spacing²

The growth multiplier is 0 during establishment, rises linearly from 0 to 1 during the ramp, and remains 1 afterward. Deductions are applied in the displayed order. Gross removal is the biological planning estimate before mortality and project-risk deductions; net is a conservative planning result, not credited CO₂.

Worked example: 1,000 trees over 30 years

The live example will appear after calculation.

Practical reforestation planning reference

Typical gross ranges

IPCC Tier 1 above-ground growth values imply broad full-stock rates of roughly 0.7–1.7 tCO₂/ha/yr for boreal systems, 5.2–7.6 for temperate systems, and 8.6–25.8 for moist tropical systems after converting dry biomass to CO₂. They are screening ranges, not site forecasts.

Planting density

Density varies with restoration objective, species, natural regeneration, and thinning. Enter a forester’s stocking prescription; if only spacing is known, the calculator converts square spacing to trees per hectare.

Factors affecting survival

Competition, herbivory, site preparation, rainfall, stock quality, planting technique, fire, pests, and maintenance can all change survival. Monitor cohorts rather than assuming one permanent percentage.

Field data to collect

Record planted area, stocking, species, planting date, permanent plot locations, live/dead status, diameter, height, disturbance, replacements, and land-use displacement. Re-measure consistently.

When specialists are needed

Use a professional forest-carbon team when making finance, credit, compliance, land-rights, or public impact claims, or when soil and other carbon pools materially affect the result.

Methodology and provenance

Responsible organizationStarlight Robotics / Starlight Tools. No independent scientific review is claimed.
Calculation version2.0.0 · Last reviewed 17 July 2026
Reported quantityTonnes of CO₂ (not carbon and not multi-gas CO₂e).
Included carbon poolSimplified above-ground woody biomass growth only.
ExcludedSoil, below-ground biomass, litter, dead wood, harvested products, project emissions, and any avoided emissions.
Intended useEarly planning, education, and scenario comparison. Results are not certified offsets or issued carbon credits.

Sources and assumption provenance

Reforestation carbon calculator FAQs

How many trees are needed to remove one tonne of CO₂?

There is no universal trees-per-tonne value. In this calculator it equals 1,000 kg divided by the selected per-tree annual rate and the applicable growth, mortality, baseline, leakage, and permanence factors. Young trees require more time, so use the project timeline rather than a one-year mature-tree shortcut.

How much land does a reforestation project require?

Land required equals the number of planted trees divided by planting density. The calculator converts acres to hectares and can derive density from square tree spacing. Actual stocking should follow local silvicultural and ecological guidance.

Why do sequestration rates vary by species and climate?

Growth depends on climate, moisture, soils, species, stand density, disturbance, and management. The presets are broad IPCC Tier 1 planning defaults, not species forecasts; local inventory or yield-table data should override them.

How does tree age change CO₂ sequestration?

The model assigns near-zero removal during establishment, then increases annual removal linearly to the selected full-stock rate. It is a transparent approximation; real stand growth curves are not linear and may decline at older ages.

How is tree mortality modeled?

Each planting cohort loses a selected percentage of surviving trees annually. The calculator uses one annual mortality rate for years 1–5 and another from year 6 onward, so survival changes with cohort age rather than being deducted once at planting.

Does the calculator include soil carbon?

No. Results include a simplified above-ground woody biomass growth pool only. Soil, litter, dead wood, below-ground biomass, harvested wood products, and project emissions are excluded because they require pool-specific field data and methodology rules.

What is the difference between carbon and CO₂?

Carbon is the element stored in biomass; CO₂ is the atmospheric gas reported here. Carbon mass is converted to CO₂ mass by multiplying by 44/12. The calculator reports tonnes of CO₂, not tonnes of carbon or broad CO₂-equivalent.

Can these results support carbon credits?

No. These planning estimates are not certified offsets or issued credits. Crediting requires an approved methodology, project boundary, baseline and additionality demonstration, leakage assessment, monitoring, verification, and a program-specific non-permanence treatment.

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