NBR: How Satellites Measure Where a Fire Burned
Fire flips a landscape's spectral signature: healthy vegetation's strong near-infrared collapses while charred ground's shortwave-infrared climbs. NBR captures that reversal, which is why it is the standard index for burn mapping.
What it actually measures
Live, healthy canopy scores high on NBR; recently burned ground scores low or negative. A single post-fire NBR shows the burn, but the real severity signal comes from comparing before and after (see dNBR).
The math behind it
where NIR is near-infrared reflectance, SWIR2 is shortwave-infrared 2 reflectance (~2.2 µm).
How to interpret the output
High positive = healthy vegetation · low or negative = recently burned. Severity is read from the pre- vs post-fire drop (see dNBR).
The bands it needs
| Sentinel-2 | NIR B8 · SWIR2 B12 |
| Landsat 8/9 | NIR B5 · SWIR2 B7 |
Real-world use
NBR underpins operational burn-severity products from fire agencies worldwide and is the first step in nearly every post-wildfire assessment.
Watch out for
One date is ambiguous — a low NBR can mean burned or merely sparsely vegetated. Always pair a pre-fire and post-fire image, and watch for phenology differences between the two dates that can masquerade as burn signal.
Compute NBR on your own study area
Skip the code. Draw or upload a boundary and Spatial Research Suite runs NBR on live Sentinel-2 or Landsat imagery — with cloud masking, exports and citations built in.
Run this analysis in GISforus →Frequently asked
What does a low NBR value mean?
Low or negative NBR indicates little healthy vegetation — either recently burned ground or naturally sparse cover, which is why a pre-fire baseline is needed to confirm burning.
NBR or dNBR for severity?
Use dNBR — the pre-minus-post difference — for severity; a single NBR only shows current condition.