How to Count Features by Attribute in QGIS (4 Methods)

This tutorial presents four different approaches to count airports in QGIS. The examples use the OurAirports dataset, where each feature represents a single airport.

Dataset

The layer contains one feature per airport and includes fields such as:

• id
• ident
• name
• type
• iso_country
• iso_region

Since each feature corresponds to one airport:

• Total airports = Number of features.
• Airports by country = Number of features grouped by iso_country.

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Method 1 – Count the Total Number of Airports

The fastest method is simply checking the feature count.

Steps

1. Open the attribute table.
2. Read the value shown in the title bar.

Example:

Features Total: 73323

Since every feature represents one airport, the dataset contains 73,323 airports.

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Method 2 – Statistics by Categories

This is the simplest tool for counting airports by country.

Steps

1. Open Processing Toolbox.
2. Search for Statistics by Categories.
3. Set:

Parameter	Value
Input layer	Airports
Field to calculate statistics	id
Categories field	iso_country

1. Click Run.

Result

The output table contains one record per country, including a count column.

Example:

iso_country	count
US	22,665
CA	1,468
BR	5,227

This method is ideal when you only need summary statistics.

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Method 3 – Aggregate Tool

The Aggregate algorithm is similar to SQL’s GROUP BY.

Step 1

Open

Processing Toolbox → Aggregate

Step 2

Choose the input layer.

Step 3

Group the records by country.

Group by expression

"iso_country"

This creates one group for every country code.

Step 4

Define the output fields.

Country field

Parameter	Value
Name	country
Type	Text
Aggregate	first_value
Expression	"iso_country"

first_value returns the first value found in each group. Since every feature in the group has the same country code, it correctly returns that country’s code.

Airport count

Parameter	Value
Name	airports
Type	Integer
Aggregate	count
Expression	"id"

The count aggregate counts the number of airport IDs within each country.

Result

country	airports
US	22,665
CA	1,468
BR	5,227

Understanding Aggregate Functions

Some commonly used aggregate functions include:

Function	Description
count	Counts records
sum	Adds numeric values
mean	Computes the average
min	Smallest value
max	Largest value
median	Median value
first_value	Returns the first value in the group
majority	Most frequent value
minority	Least frequent value
concatenate	Joins text values

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Method 4 – SQL

If you are familiar with SQL, this is often the most flexible solution.

Open

Layer → Add Layer → Add/Edit Virtual Layer

or

Processing Toolbox → Execute SQL

Then run:

SELECT
    iso_country,
    COUNT(*) AS airports
FROM "31_airports"
GROUP BY iso_country
ORDER BY airports DESC;

Replace "31_airports" with the actual name of your layer if it is different.

Result

iso_country	airports
US	22,665
BR	5,227
CA	1,468

Using SQL makes it easy to add additional statistics, for example:

SELECT
    iso_country,
    COUNT(*) AS airports,
    AVG(elevation_ft) AS avg_elevation,
    MAX(elevation_ft) AS highest_airport
FROM "31_airports"
GROUP BY iso_country
ORDER BY airports DESC;

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Which Method Should You Use?

Method	Best Use
Feature count	Total number of airports
Statistics by Categories	Quick counts by country
Aggregate	Build summary tables inside QGIS
SQL	Complex summaries and reusable queries

For simple summaries, Statistics by Categories is usually the fastest option. When more control over the output is required, the Aggregate tool or SQL provides much greater flexibility.