Tempo in music is beats perceived by us in unit time. The tempo is measured as number of beats per minute (BPM) in a music clip. This paper presents a system for automatically calculating tempo of audio music signal. In this system, as an initial step after giving sound clip as an input, a threshold percentage in decibels selected. In the next step, samples having values above the threshold are considered as beats. We have used Audacity as an open source tool for the initial experiments. By using nyquist programming in audacity which is used specially for sound, we have added a nyquist plug-in in the Audacity open source software. This paper talks about the two newly added plugins by us which shows the beat positions of the selected sound clip and the time instances of these beats are retrieved using nyquist programming and thus using this equidistant beats are located, whereas the other plugin shows the actual calculated tempo of the same sound clip. Total number of beats is calculated from selected clip and using this beats per minute are obtained. The tempo of the sound clip is calculated based on the basic formula for beats per minute in which the total length of the sound clip is calculated and with the help of this, number of beats per minutes is obtained. For the sound clips which have more number of beats per minute has more tempo and those sound clips with less number of BPM or medium BPM has less or medium tempo respectively. This paper proposes the algorithm which gives the best results for rhythmic sound clips.