How to calculate return on investment after buying cryptocurrency?

For those new to the world of cryptocurrency investing, understanding how to calculate return on investment (ROI) can be crucial for tracking performance and making informed decisions. Could you elaborate on the steps involved in calculating ROI after purchasing a cryptocurrency? Specifically, I'm interested in understanding how to factor in the initial investment amount, the current market price, any associated transaction fees, and how to account for potential fluctuations in the cryptocurrency's value over time. Additionally, would you recommend any specific tools or platforms to assist with this calculation? Clarifying this process would greatly benefit those looking to enter or expand their portfolio in the crypto market.