Hello, thank you for your interest. Based on the height and weight information you provided (178 cm, 85 kg), depending on your body structure and clothing preference, **XL (Size 42)** or **XXL (Size 44)** will be suitable in our **Black Patterned Slit Detailed Long Dress** model. If you want the product to fit you better, you can consider size **XL**. If you prefer a more comfortable and loose fit, you can consider size **XXL**. If you have a different question, we will be happy to help. We wish you pleasant shopping! Madmext Team