Balsthal has an area, as of 2009, of 15.71 square kilometers (6.07 sq mi).
Of this area, 4.62 km² (1.78 sq mi) or 29.4% is used for agricultural purposes, while 8.53 km² (3.29 sq mi) or 54.3% is forested.
Of the rest of the land, 2.26 km² (0.87 sq mi) or 14.4% is settled (buildings or roads), 0.1 km² (25 acres) or 0.6% is either rivers or lakes and 0.18 km² (0.069 sq mi) or 1.1% is unproductive land.

Of the built up area, industrial buildings made up 2.2% of the total area while housing and buildings made up 7.3% and transportation infrastructure made up 3.6%.
Out of the forested land, 53.1% of the total land area is heavily forested and 1.2% is covered with orchards or small clusters of trees.
Of the agricultural land, 6.4% is used for growing crops and 19.7% is pastures and 2.7% is used for alpine pastures.
All the water in the municipality is flowing water.

The municipality is located in the Thal district.
It was a market town and administrative center for the Oberen Hauenstein.
It consists of the village of Balsthal, the industrial settlement of Klus and the hamlets of Sankt Wolfgang.
Balsthal has an area, as of 2009, of 15.71 square kilometers (6.07 sq mi). Of this area, 4.62 km² (1.78 sq mi) or 29.4% is used for agricultural purposes, while 8.53 km² (3.29 sq mi) or 54.3% is forested. Of the rest of the land, 2.26 km² (0.87 sq mi) or 14.4% is settled (buildings or roads), 0.1 km² (25 acres) or 0.6% is either rivers or lakes and 0.18 km² (0.069 sq mi) or 1.1% is unproductive land.
Of the built up area, industrial buildings made up 2.2% of the total area while housing and buildings made up 7.3% and transportation infrastructure made up 3.6%. Out of the forested land, 53.1% of the total land area is heavily forested and 1.2% is covered with orchards or small clusters of trees. Of the agricultural land, 6.4% is used for growing crops and 19.7% is pastures and 2.7% is used for alpine pastures. All the water in the municipality is flowing water.
The municipality is located in the Thal district. It was a market town and administrative center for the Oberen Hauenstein. It consists of the village of Balsthal, the industrial settlement of Klus and the hamlets of Sankt Wolfgang.
Balsthal