In Sweden the official method for estimating plant available potassium (K) is well calibrated to Swedish soils, but mainly provides information about exchangeable K. The objective was to evaluate a 0.01 M calcium chloride (CaCl2) solution (K‐CaCl2), with regard to its compatibility with standard laboratory procedures, and the relationship between the K‐CaCl2method and official Swedish methods depending on soil and fertilizing strategy. Soil was taken from long‐term field experiments with no K application or with applications of 160–240 K kg ha‐1yr‐1at Vojakkala, Ultuna, and Rådde. The soil samples, air‐dried or at field moisture content, were extracted by 0.01M CaCl2at two different soil:extractant ratios (1:2 and 1:10), and analyzed by inductively coupled plasma emission spectrometry (ICP) for K content. In Sweden, the official method for estimating plant available soil K is the ammonium lactate/acetic acid (AL) method and non‐exchangeable K is estimated in 2M HCl (K‐HCl). Amounts of K‐CaCl2from field‐moist and air‐dried soil were significantly affected by soihextractant ratio 1:2 or 1:10. This indicated that the same fraction of K in soil was not always extracted and that the amount depended on soil and fertilizing strategy. A soil:extractant ratio of 1:10 was preferable in order to get clear extracts. Air‐dried soil samples were most suitable for Swedish laboratory procedures. Overall, CaCl2extraction gave smaller amounts of K than AL and HC1 extraction. However, at Vojakkala and Radde treatments with K application considerably increased amounts of K‐CaCl2and K‐AL, compared with no K application. In treatments with no K application, amounts of K‐CaCl2and K‐AL were largest at Ultuna. There was a clear difference among sites in amounts of K‐ HC1. There seemed to be a good relationship between the K‐CaCl2and the K‐AL methods. However, the K‐CaCl2method extracted smaller amounts indicating that mostly K in soil solution was extracted. In Sweden, CaCl2could be a good complement to AL and HC1 extractable K and give a more complete description of K availability on different soil types and under different fertilizing strategies and could easily be incorporated into Swedish laboratory procedures.