What is EVI? (Enhanced Vegetation Index)
What is EVI?
EVI, the Enhanced Vegetation Index, is a satellite vegetation index that does the same job as NDVI — measuring how healthy and dense your crop canopy is — but stays accurate where NDVI gives up: over very lush, high-biomass vegetation. If NDVI is the everyday tool, EVI is the one you reach for when the canopy is so thick that NDVI stops being able to tell you anything more. Tropical forest, a peak-season corn field, a densely planted sugarcane block — these are EVI territory.
How it’s calculated
EVI uses the same near-infrared and red bands as NDVI, but adds a third: blue. The blue band lets EVI correct for atmospheric haze (which scatters blue light), and a soil-adjustment factor reduces the influence of bare ground. The result is an index that keeps rising as vegetation gets denser, long after NDVI has flattened out.
EVI = G × (NIR − Red) / (NIR + C1 × Red − C2 × Blue + L)On Sentinel-2 these are Band 8 (NIR), Band 4 (Red), and Band 2 (Blue), with constants G = 2.5, C1 = 6, C2 = 7.5, L = 1. Because Sentinel-2 surface-reflectance values are stored on a 0–10,000 scale (not 0–1) and EVI’s formula adds and subtracts bands rather than taking a pure ratio, the scale factor does not cancel. The soil-adjustment term L must be scaled to match — implemented as 10000 in DN space. Getting this wrong produces plausible-looking nonsense numbers.
Typical value ranges
EVI covers roughly the same 0–1 range as NDVI but spreads its useful values higher, because it does not compress at the top.
| EVI range | Meaning | Typical for |
|---|---|---|
| 0.6 – 0.9 | Very dense, vigorous vegetation | Tropical forest, peak-season row crops at canopy closure |
| 0.4 – 0.6 | Healthy, moderately dense | Well-developed crop canopy, mature plantations |
| 0.2 – 0.4 | Moderate / developing | Early-to-mid growth, orchards with open rows |
| 0.0 – 0.2 | Sparse or bare | Bare soil, very early growth, senesced vegetation |
| Below 0 | Water, snow, cloud | Open water, snow, dense cloud |
As with NDVI, the absolute number matters less than the trend — a sudden drop is a stress signal regardless of where you started.
When to use it
Switch to EVI when the canopy is dense (roughly NDVI above 0.7–0.8). At that point NDVI saturates — it keeps returning nearly the same value even as biomass keeps climbing. EVI keeps responding, so it can distinguish “dense” from “even denser.” Prefer EVI in hazy or humid regions too — the blue-band atmospheric correction helps where NDVI alone is degraded by haze, common in tropical and coastal agriculture.
For a vineyard or orchard (open canopies), NDVI is usually the better choice. For corn, sugarcane, rice at peak, or forest, EVI is the more honest number. Where NDVI flattens into a plateau over a dense crop, EVI continues to rise and fall with true canopy development, making it better at revealing late-season stress that NDVI would hide under its saturation ceiling.
Comparison with other indices
EVI is essentially NDVI with atmospheric correction and saturation resistance — use it when NDVI stops improving over dense canopies. For sparse crops where soil background is the problem (not saturation), SAVI or MSAVI2 are more appropriate than EVI. NDMI pairs well with EVI for high-biomass irrigation: EVI tracks canopy growth while NDMI tracks the water inside it. NDRE offers different information entirely (nitrogen status), making it complementary rather than a competitor.
Try it free: Get EVI values for your field — free, no signup. Works on any land worldwide. Check my field’s vegetation health →
Frequently asked questions
Is EVI better than NDVI?
Neither is universally “better.” EVI is more accurate over dense canopies (where NDVI saturates and stops changing) and in hazy conditions. For most open-canopy crops and general monitoring, NDVI is simpler and equally valid. The best reports show both and interpret them together.
Why does EVI use the blue band?
The blue band lets EVI correct for atmospheric scattering (haze, aerosols), which preferentially scatters shorter blue wavelengths. Subtracting a fraction of blue sharpens the signal in conditions where NDVI alone would be degraded. It also introduces a dependency on good atmospheric correction, so EVI is more picky about image quality.
What is a good EVI value for crops?
For a healthy annual crop at peak growth, 0.5 to 0.8 is typical. Forests can exceed 0.8. As always, compare against your own field’s seasonal pattern rather than an absolute threshold — a drop of 0.2 is a stress signal regardless of the starting value.
Can EVI detect drought?
Yes — a falling EVI over a dense canopy can reveal drought stress that NDVI would hide beneath its saturation ceiling. For this reason EVI is valuable for irrigated high-biomass crops and forest health monitoring. Pair it with NDMI (moisture) for a clearer picture.