In Jainism, a yantra is mainly a sacred diagram used as a supporting tool in worship and meditation – not the main path of dharma.

Very simply, the purpose of having a yantra is:

1. To focus the mind on dharma

- The design (circles, petals, numbers, names of Parmesthi, Navpad, etc.) works like a visual aid. - When you look at it and do mantra–jaap (like Navkar, stotra, etc.), your mind becomes more concentrated and less distracted.

1. To constantly remember the higher ideals

- Yantras like Siddhachakra / Navpad Yantra remind us of: - Arihant, Siddha, Acharya, Upadhyay, Sadhu - Samyak Darshan, Samyak Gyan, Samyak Charitra, Samyak Tap - So the purpose is smruti (constant remembrance) of the path to moksha.

1. To support inner purification (bhāva–śuddhi)

- While doing puja, prarthana, or sādhanā in front of a yantra, the main thing is shuddha bhāva: - reducing anger, ego, deceit, greed - increasing forgiveness, humility, simplicity, non-violence - The yantra is only a tool; the real change is in your inner qualities.

1. To help in certain traditional vidhis

- Some Jain traditions (especially Śvetāmbara) use different yantras (Siddhachakra, Navkar Yantra, Bhaktamar Yantras, etc.) in specific pujas and vidhans. - There the yantra: - gives a fixed method (niyam) of worship - organizes mantras and devatā–sāmāyik in a clear visual form.

1. Not a replacement for core Jain practice

- Core Jain path is: - Samyak Darshan, Samyak Gyan, Samyak Charitra - Ahimsa, vrata, sāmāyik, pratikraman, svādhyāy, dhyān - Yantra is secondary / supportive. It should not be treated as a magical object or shortcut for worldly gain.

Sect note (Digambar / Shwetambar)

• Śvetāmbara: Yantras like Siddhachakra, Navpad, various devi–devta yantras are more commonly used in rituals and vidhans.
• Digambar: Some yantra traditions exist (especially connected with Bhaktamar, etc.), but overall more emphasis is kept on stotra, dhyān, vrata than on yantras themselves.
• In both, the essence is same: if yantra is used, it must lead to more vivek, more vairāgya, and less pāp–bandh, not more attachment.

You can read a simple explanation of Jain yantras and Siddhachakra here