Reclassifying Rasters with a Table of Values
Reclassifying raster datasets is the process of producing a new raster dataset based on an existing raster layer, with values corresponding to a classification method that you establish. While spatial resolution is maintained, the granularity of the attribute information (cell values) is diminished in the process in favor of grouping attribute values into desired classes.
Included in this tutorial:
Accessing the Reclassify by Table Tool
Reclassify by Table Tool Options and Parameters
Example Reclassification
Software version in examples: QGIS-LTR 3.44.10-Solothurn
Tutorial Data: The tutorial includes demonstration with sample data available here.
Credits: Sally Kaye and L. Meisterlin (2026)
This tutorial walks through the Reclassify By Table tool in QGIS, which requires an input of manual breaks for reclassification. The input raster in this example was produced by converting the Tracts_prj layer in the Tutorial Data Standard Data Package to a raster layer, using the values in the Shape_Length field (as an arbitrary numeric variable).
Accessing the Reclassify by Table Tool
You can find the Reclassify By Table tool by clicking the Processing Toolbox icon > Raster Analysis > Reclassify by table.
locating the Reclassify tool in the Processing Toolbox
Reclassify By Table Tool Options and Parameters
Reclassify by table tool inputs
Here’s a brief description of the different inputs:
Raster layer: The input raster to be reclassified.
Band number: Band with values to be reclassified. This is relevant for multi-band rasters, which include values from more than one band within a composite raster dataset. For a single-band raster, the default option will be Band 1.
Reclassification table: This is a three-column table that sets the range of original values that will correspond to each new class. To set up the table for your reclassification, click the three dots icon next to this input.
Reclassified raster: Choose where to save the output raster. By default, QGIS will create a temporary layer in the current project, or click the three dots icon to select a file location and name for the new raster.
In the Advanced Parameters dropdown, you can optionally set an alternative output value for cells with no data, change range boundaries (the default is min < value <= max) and change the output data type.
Setting up the Reclassification Table
reclassification table
Establishing the number of classes: In the reclassification table window, use the Add Row, Remove Row(s),and Remove All buttons to customize the number of classes in the reclassified raster.
Specify the range for each class: The minimum and maximum columns specify the range of each class from the input raster raster that will be reclassified.Type the relevant values into each of these columns. Some tips: The values -inf and inf can be used to represent the minimum value and maximum value respectively (they are abbreviations for “negative infinity” and “infinity”).
Specify the new value for each class: Type into the Value column to specify the new value that will be assigned to cells within each class (in the output raster). Tip: you can type nan to set an output value as “NoData” or null.
When you are happy with your reclassification table, click OK to return to the main inputs page and click Run to generate the reclassified output raster.
Note: All cells within the table must be filled out for reclassification to complete.
Example Reclassification
In this example, we reclassify the “rastertestshapelength” raster (generated by rasterizing the Tracts_prj layer in the Standard Data Package based on the shape_length field) using the steps above, with breaks of 5000. The output raster is simplified, with fewer shades symbolizing its values.
example reclassification table
reclassified output raster