Want to know how to calculate IWO? The Cost of Goods Sold (IWO) is one of the most important financial metrics for every entrepreneur - and especially for sellers on bol.com. IWO shows how much you paid for the products you actually sold. In this comprehensive article, we'll explain step by step what IWO is, how to calculate it, which formulas to use, and how to use IWO to improve your profit margin.
What is IWO (Cost of Goods Sold)?
IWO stands for Cost of Goods Sold and refers to the total purchase costs of the products you sold in a given period. It's not the value of your entire inventory, but specifically the costs of the products that were actually sold. IWO is also known as COGS in English.
For bol.com sellers, IWO is essential to understand whether you're really making a profit. You can have high sales, but if your purchase costs are also high, there's not much left. IWO helps you make that distinction clear and gives you control over your gross margin.
How to calculate IWO? The formula step by step
The basic formula to calculate IWO is simple but powerful:
IWO = Beginning Inventory + Purchases − Ending Inventory
This includes:
- Beginning Inventory: the value of your inventory at the start of the period (month, quarter, or year)
- Purchases: all purchase costs of new products you bought during that period, including shipping costs, customs duties, and import fees
- Ending Inventory: the value of your inventory at the end of the period
Let's say you start the month with €5,000 in inventory, buy €3,000 worth of new products, and have €4,000 in inventory at the end of the month. Then your IWO is: €5,000 + €3,000 − €4,000 = €4,000.
Calculating IWO: practical examples
To better understand how IWO calculation works in practice, check out the examples below for different types of bol.com sellers.
| Scenario | Beginning Inventory | Purchases | Ending Inventory | IWO | Sales | Gross Profit |
|---|---|---|---|---|---|---|
| Small seller (1 product) | €1,000 | €500 | €600 | €900 | €2,200 | €1,300 |
| Average seller (10 products) | €5,000 | €3,000 | €4,000 | €4,000 | €8,500 | €4,500 |
| Larger seller (50+ products) | €25,000 | €15,000 | €20,000 | €20,000 | €42,000 | €22,000 |
| Seasonal seller (December peak) | €10,000 | €20,000 | €5,000 | €25,000 | €55,000 | €30,000 |
| Dropshipper (no own inventory) | €0 | €8,000 | €0 | €8,000 | €14,000 | €6,000 |
For a dropshipper, the calculation is the simplest: IWO is equal to the total purchases, since there's no beginning or ending inventory. For sellers with their own inventory, it's crucial to keep track of what you have in stock accurately.
What costs are included in IWO?
A common mistake is to only consider the purchase price of products. However, IWO includes áll direct costs necessary to make a product saleable:
| Cost Item | Included in IWO | Description |
|---|---|---|
| Product Purchase Price | Yes | The price you pay to your supplier |
| Shipping Costs to You | Yes | Transport costs from supplier to your warehouse |
| Customs and Import Costs | Yes | Import duties when importing from e.g. China |
| Packaging Costs | Yes | Costs for product packaging |
| Bol.com Commission | No | These are sales costs, not purchase costs |
| Shipping Costs to Customer | No | These are distribution costs |
| Marketing Costs | No | Advertising and advertising costs are operational costs |
| Storage Costs (LVB) | No | Storage costs are overhead costs |
Correctly assigning costs to the IWO is important for a clean gross margin calculation. If you import via Alibaba, don't forget to include customs costs and international shipping in your purchase price per unit.
IWO versus other financial metrics
The IWO does not stand alone. To fully understand your company's performance, you need to combine the IWO with other financial metrics. Below is an overview of the most important comparisons:
| Metric | Formula | What it measures | Relationship to IWO |
|---|---|---|---|
| Gross Profit | Revenue − IWO | Profit after deduction of product costs | Directly dependent on IWO |
| Gross Margin (%) | (Revenue − IWO) / Revenue × 100 | Percentage of revenue that remains | Higher IWO = lower margin |
| Net Profit | Gross Profit − all other costs | Final profit | IWO is the first deduction |
| Inventory Turnover | IWO / average inventory | How quickly inventory sells | IWO as numerator |
| Break-even | Fixed costs / gross margin | Minimum revenue for profit | IWO affects gross margin |
The profit calculation always starts with the IWO. Use the Boloo Profit Calculator to quickly calculate whether a product is profitable after deducting IWO, commissions, and shipping costs.
How to track your IWO as a bol.com seller?
Manually tracking your IWO can be time-consuming, especially as your product range grows. There are several methods to systematically track your IWO:
1. Excel or Google Sheets
For starters with a small product range (1-10 products), a simple spreadsheet is sufficient. Create columns for product name, purchase price per unit, number sold, and total IWO per product. The formula per product is simple: purchase price × number sold = IWO per product.
2. Accounting Software
As your product range grows, accounting software becomes indispensable. Programs like Moneybird, e-Boekhouden, or Exact Online automatically calculate your IWO based on your purchase and sales invoices. This saves time and reduces errors.
3. Boloo Sales Dashboard
With the Boloo Sales Dashboard, you can set your product costs per item and automatically monitor your profit margin. The dashboard combines your sales data from bol.com with your set purchase costs, allowing you to see in real-time how your IWO is developing. In combination with the Profit Calculator, you have direct insight into your gross profit per product.
Common mistakes when calculating the IWO
Many entrepreneurs make mistakes when calculating their IWO, resulting in a distorted view of their profitability. These are the most common pitfalls:
- Forgetting additional costs: Only considering the purchase price and neglecting shipping, customs, and packaging costs. This results in a lower IWO and an overestimated profit margin
- Inaccurate inventory counting: If your beginning or ending inventory is incorrect, your IWO calculation is wrong. Perform regular inventory counts (at least quarterly)
- Not processing returns: Products returned by customers must be added back to your inventory, which reduces your IWO for that period
- Ignoring different purchase prices: If you purchase the same product at different times and prices, you must choose a method: FIFO (First In, First Out) or weighted average
- Confusing sales and purchase costs: Bol.com commissions, shipping costs to customers, and advertising costs are not part of the IWO
Optimizing IWO: tips for a better margin
A lower IWO with the same revenue automatically means a higher gross profit. Here are proven strategies to reduce your IWO:
1. Negotiate better purchase prices
Order larger quantities from your supplier to get volume discounts. With suppliers on Alibaba, you can often get 10-30% discounts for larger orders. Always compare multiple suppliers before making a purchase.
2. Reduce your additional costs
Optimize your logistics chain: choose cheaper shipping services for your imports, consolidate shipments, and research whether LVB or your own shipping is more cost-effective for your situation.
3. Minimize shrinkage and returns
Damaged products and high return rates increase your effective IWO. Invest in good packaging and accurate product descriptions via the Listing Generator AI to reduce returns.
4. Use data for purchasing decisions
Analyze which products have the best margin using the Boloo Product Tracker. Focus your purchasing on products with a low IWO relative to their selling price. Use the Product Database to find new products with a favorable margin.
IWO and tax return
The IWO plays a crucial role in your tax return. The tax authorities require you to correctly account for the IWO in your profit and loss account. Here are the key points to consider:
- Inventory valuation: You must use a consistent method for valuing your inventory (FIFO, LIFO, or weighted average). The most commonly used method in the Netherlands is FIFO
- Retention obligation: Keep all purchase invoices for at least 7 years as supporting documentation for your IWO
- Depreciation: You can depreciate unsellable or damaged inventory, which can affect your IWO for the relevant year
- Automatic invoicing: Use automatic invoicing to always keep your purchase and sales invoices in order
Inventory valuation methods for IWO
The method you choose for inventory valuation has a direct impact on your IWO calculation:
| Method | How it works | Advantage | Disadvantage |
|---|---|---|---|
| FIFO (First In, First Out) | Oldest stock is sold first | Most realistic with rising prices | Higher IWO with falling prices |
| Weighted average | Average purchase price of all stock | Easy with fluctuating prices | Less accurate per individual product |
| LIFO (Last In, First Out) | Newest stock is sold first | Lower profit (tax benefit) | Not allowed under IFRS |
| Specific identification | Each unit at actual purchase price | Most accurate | Only feasible with few products |
For most bol.com sellers, FIFO or the weighted average is the best choice. Choose one method and apply it consistently - the tax authorities expect consistency in your inventory valuation.
Frequently Asked Questions about Calculating IWO
What is the difference between IWO and purchase price?
The purchase price is the price per product that you pay to your supplier. The IWO is the total purchase value of all products that you have actually sold in a certain period, including additional costs such as shipping and customs. The IWO is therefore a broader measure that reflects the total cost of your sold goods.
How often should I calculate my IWO?
We recommend calculating your IWO at least monthly. For busy periods (such as seasonal peaks) it can be valuable to do this weekly. The more often you keep track of your IWO, the faster you can adjust if your margin is under pressure.
Does the bol.com commission count towards the IWO?
No. The bol.com commission is a sales cost, not a purchase cost. Commissions belong to the operational costs and are only deducted after the gross profit calculation (Revenue - IWO). The same applies to advertising costs and shipping costs to the customer.
How do you calculate IWO with dropshipping?
With dropshipping you don't have your own stock, which simplifies the formula to: IWO = total purchases. Your beginning and ending inventory are both €0. Every order you place with your supplier is directly part of your IWO.
What is a healthy IWO ratio for bol.com sellers?
A healthy IWO is usually between 30% and 60% of your revenue, depending on your product category. Electronics often have a higher IWO (50-70%), while accessories and household products have lower purchase costs (25-40%). Monitor your IWO ratio regularly via the Boloo Sales Dashboard to detect trends.
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