Choosing the right brown mascara for your eye color involves understanding the color wheel and how different shades can enhance or complement your natural eye color. Here's a simple guide to help you choose the right brown mascara:

1. **Blue Eyes**: If you have blue eyes, a warm brown mascara can help to make your eyes pop. The warm undertones in the mascara will contrast with the cool undertones in your eyes, making them appear brighter and more vibrant.

2. **Green or Hazel Eyes**: For green or hazel eyes, a deep, rich brown mascara can help to highlight the green tones in your eyes. This is because brown and green are analogous on the color wheel, meaning they complement each other well.

3. **Brown Eyes**: If you have brown eyes, you're in luck because most shades of brown mascara will complement your eye color. However, if you want to add some depth to your look, opt for a dark brown mascara. This will create a subtle contrast with your eye color, making them appear deeper and more mysterious.

4. **Gray Eyes**: For gray eyes, a light brown mascara can help to add some warmth to your look. This is because the warm tones in the mascara will contrast with the cool tones in your eyes, making them appear more vibrant.

Remember, the right brown mascara for you also depends on your skin tone, hair color, and personal style. It's always a good idea to experiment with different shades to see what works best for you.