No, sheer cotton curtains do not provide full privacy. While cotton curtains made with sheer or thin fabric allow natural light to enter the room and give a soft, elegant look, they are often too see-through to block views from outside, especially during the evening or night when lights are on inside.
If you're looking for privacy, sheer cotton curtains are not the best choice on their own. They work well during the day to filter sunlight but do not prevent outsiders from seeing into your home. To increase privacy, many people layer cotton curtains with thicker drapes or use blinds behind them. This way, you can enjoy the soft look of cotton curtains and still have the option to block visibility when needed.
For better privacy, you can go for cotton curtains that are made with a denser weave or choose blackout cotton-lined options. Always check the fabric thickness and hold it up to the light before buying. In short, cotton curtains are great for style and light filtering, but if privacy is your main concern, consider pairing them with other window treatments.