Leaf Area Index Calculator

Work out leaf area index instantly with clear inputs, formula shown and shareable results.

About Leaf Area Index Calculator

Divides leaf area by ground area for the leaf area index, then applies the Beer-Lambert canopy law to estimate light interception.

Formula

Leaf area index and light

LAI = leaf area / ground area; fraction intercepted = 1 - e^(-k x LAI), with k about 0.5 for horizontal leaves

Worked example

With the default values below, Leaf Area Index Calculator returns Leaf area index of 4.500. Change any input above and every figure here is recalculated in your browser.

Inputs used

Total one-sided leaf areaaccepts 0.01–100,000 m2: 45 m2
Ground areaaccepts 0.01–100,000 m2: 10 m2
Light extinction coefficientaccepts 0.1–1.2: 0.5

Results

Leaf area index: 4.500
Light intercepted by the canopy: 89.46%
Light reaching the ground: 10.54%
Leaf area index needed to intercept 90%: 4.61

Step by step

1Values used
2Leaf area index and light
3Leaf area index= 4.500
4Light intercepted by the canopy= 89.46
5Light reaching the ground= 10.54
6Leaf area index needed to intercept 90%= 4.61

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

What LAI do crops reach?

Typically 3 to 6 at full canopy, above which extra leaves are shaded and add little production.

What does the extinction coefficient represent?

Canopy architecture: erect leaves give a low coefficient near 0.3, horizontal leaves nearer 0.8.