The average cost of interior design can vary widely based on factors such as location, the scope of the project, the level of customization, and the experience and reputation of the interior designer. Here are some rough estimates to give you an idea:

Consultation Fees: Initial consultations may range from $50 to $500 per hour, depending on the designer’s expertise.
Design Fees: Design fees can vary significantly and may be charged per hour, per square foot, or as a flat fee. On average, you might expect to pay anywhere from $1,000 to $10,000 or more for design services.
Project Management Fees: If your designer is overseeing the project, project management fees can add another 10% to 20% to the total project cost.
Materials and Furnishings: The cost of materials and furnishings is highly variable. For a full-scale interior design project, including furniture, lighting, textiles, and accessories, you could be looking at a range of $5,000 to $50,000 or more.
Labor Costs: If your project involves renovations or construction work, labor costs for contractors, painters, and other professionals should be factored in. This can significantly increase the overall cost.
Contingency Fund: It’s recommended to set aside 10% to 20% of the total budget as a contingency fund to cover unforeseen expenses.

Keep in mind that these are general estimates, and costs can vary widely based on individual circumstances. Additionally, some designers may work on smaller projects with lower budgets, while others may specialize in high-end or luxury designs with correspondingly higher costs. To get an accurate estimate for your specific project, it’s best to consult with multiple designers and contractors, providing them with details about your preferences, scope, and budget constraints.