India's currency is the Indian rupee, code INR. Start with the rupee amount required when you are paying a bill or helping cover a known expense. If you have a fixed budget in your own currency, calculate in the other direction to estimate its value in rupees.
For regular family payments, use the same starting amount when comparing offers. That makes changes in the exchange rate and fees easier to see. Keep a separate note of any recipient amount that must be met, rather than assuming last month's payment will cover it again.
Before sending, confirm the recipient's details and the delivery methods offered for your sending country. The provider may request information about the payment. Compare its final fee and received amount, and check when its arrival estimate starts. A published INR rate does not establish that every provider supports your transfer.
Currency background: Indian rupee (INR) — Wise · Wise US-to-India transfer page