1. Define the Scope of Work: To accurately estimate the cost to build a ecommerce website, you will need to define the scope of work. This includes the features, functionality, and design elements that will be included in the project.

2. Choose a Platform: Decide on the platform that you will use to build the ecommerce website. Common choices include Shopify, Magento, WooCommerce, and BigCommerce.

3. Research Costs: Research the costs associated with the platform that you have chosen. Platforms have different pricing models, and you will need to know the cost of each to accurately estimate the cost of building an ecommerce website.

4. Include Design Costs: Design costs vary depending on the complexity of the website design. You will need to include the cost of the design in your estimate.

5. Estimate Development Costs: Development costs can vary depending on the complexity of the project. Estimate the cost of development by taking into consideration the time it will take to write code, develop the website, and debug any issues.

6. Estimate Hosting Costs: Hosting costs are typically included in the cost of the platform, but you may need to factor in additional hosting costs depending on the size of your website.

7. Include Maintenance Costs: Maintenance costs should be included in your estimate to ensure that the website is kept up to date and running smoothly.

8. Add Contingency Cost: Finally, add a contingency cost to your estimate to cover any unexpected costs.

By following these steps, you can accurately estimate the cost of building an ecommerce website.