Calculate IWO

Wondering how to calculate the IWO? The IWO - Purchase Value of Sales - is an essential financial figure for every entrepreneur selling products, especially for sellers on bol.com. By calculating your IWO correctly, you'll know exactly what your sold products cost you and can determine your gross profit. In this article, we'll explain step by step how to calculate the IWO, with clear formulas, calculation examples, and practical tips.

What is the IWO (Purchase Value of Sales)?

The IWO stands for Purchase Value of Sales and represents the total cost price of all products you've actually sold in a given period. In English, this is called COGS (Cost of Goods Sold). It's essential to understand that the IWO isn't the same as the value of your total inventory - it specifically concerns the purchase costs of the goods that have been sold to customers.

For bol.com sellers, the IWO is the first step in determining whether you're really making a profit. A high turnover doesn't mean much if your purchase costs are also high. The IWO provides insight into this and forms the basis for your profit calculation.

How to calculate the IWO? The basic formula

The standard formula for calculating the IWO is:

IWO = Initial Inventory + Purchases − Final Inventory

Each variable in this formula has a specific meaning:

• Initial Inventory: the total value of your inventory at the beginning of the measurement period (week, month, quarter, or year)
• Purchases: the total purchase costs of all new products you've bought during the period, including additional costs like shipping costs to your warehouse and any import duties
• Final Inventory: the total value of your inventory at the end of the measurement period

The logic is simple: you start with a certain inventory value, add the new purchases, and then subtract what's left. The result is the cost price of everything you've sold.

Calculating the IWO step by step with examples

Let's put the formula into practice with concrete examples that apply to different types of bol.com sellers.

Example 1: Starting seller

Suppose you're just starting to sell on bol.com. At the beginning of January, you have €2,000 worth of inventory. During the month, you buy €1,500 worth of new products. At the end of January, you have €1,800 worth of inventory left.

IWO = €2,000 + €1,500 − €1,800 = €1,700

So, you've sold products worth €1,700 (at purchase value). If your turnover in January was €3,500, your gross profit is: €3,500 − €1,700 = €1,800.

Example 2: Experienced seller with a large assortment

A seller with 50 products starts the quarter with €30,000 worth of inventory. During the quarter, €18,000 is spent on purchases (including €2,000 in shipping and customs costs from China). The final inventory is €22,000.

IWO = €30,000 + €18,000 − €22,000 = €26,000

Situation	Initial Stock	Purchases	Final Stock	IWO	Revenue	Gross Margin
Starting Seller	€2.000	€1.500	€1.800	€1.700	€3.500	51%
Growing Seller	€8.000	€5.000	€6.500	€6.500	€13.000	50%
Experienced Seller	€30.000	€18.000	€22.000	€26.000	€55.000	53%
Seasonal Seller (peak)	€15.000	€25.000	€8.000	€32.000	€70.000	54%
Dropshipper	€0	€10.000	€0	€10.000	€18.000	44%

With dropshipping, the IWO calculation is the simplest: without initial and final stock, the IWO is equal to your total purchases.

Which costs are included in the IWO and which are not?

A common mistake is incorrectly assigning costs. Not all business costs are part of the IWO. Below is a clear overview:

Cost Type	Part of IWO?	Why?
Product Purchase Price	Yes	Direct product costs
Shipping Costs to Your Warehouse	Yes	Costs to make the product sale-ready
Import Duties and Customs	Yes	Direct costs when importing
Packaging Materials	Yes	Necessary to sell the product
Bol.com Commission	No	Sales costs, not purchase costs
Shipping Costs to Customer	No	Distribution costs
Advertising Costs	No	Marketing costs, not product costs
LVB Storage Costs	No	Overhead costs for storage
Office and Personnel Costs	No	General business costs

If you import products via Alibaba, make sure to include the entire import chain in your purchase price per unit: product price + international shipping + customs costs + any inspection costs.

IWO and Calculating Your Gross Margin

The IWO is directly linked to your gross margin. The gross profit formula is simple:

Gross Profit = Revenue − IWO

And your gross margin as a percentage:

Gross Margin (%) = (Revenue − IWO) / Revenue × 100

A healthy gross margin for bol.com sellers is usually between 40% and 60%, depending on the product category. Electronics often have a margin of 25-40%, while household items and accessories often reach 50-65%. With the Boloo Sales Dashboard, you can automatically monitor your gross margin per product.

Gross Margin per Product Category

Product Category	Typical IWO Ratio	Average Gross Margin	Notes
Electronics	60-75%	25-40%	High purchase costs, low margin per unit
Household & Kitchen	35-50%	50-65%	Good margins with smart purchasing
Toys & Games	40-55%	45-60%	Seasonal demand
Sports & Outdoor	40-55%	45-60%	Strong brand loyalty
Clothing & Accessories	30-45%	55-70%	High returns pressure margin
Books & Media	50-65%	35-50%	Fixed book prices (law)

Inventory Valuation: Which Method Do You Choose?

The way you value your inventory has a direct impact on your IWO calculation. There are four common methods:

FIFO (First In, First Out)

With FIFO, you assume that the oldest inventory is sold first. This is the most widely used method in the Netherlands and is considered the most realistic, especially when purchase prices are rising. The IWO then reflects the older (and often lower) purchase prices, resulting in a higher gross profit.

Weighted average

With the weighted average, you calculate the average purchase price of all your inventory. This is easy to apply when you purchase the same product at different times and prices. The formula: average purchase price = total inventory value / total number of units.

LIFO (Last In, First Out)

With LIFO, the newest inventory is counted as sold first. Note: LIFO is not allowed under IFRS accounting rules and is rarely used in the Netherlands. However, it can provide a tax advantage when prices are rising, as the IWO will be higher.

Specific identification

For expensive or unique products, you can value each unit at its actual purchase price. This is the most accurate method, but it's only practical for a small and diverse range of products.

Lowering your IWO: practical strategies

A lower IWO with the same revenue automatically means higher gross profit. Here are proven strategies to reduce your IWO:

• Volume discount: Order larger quantities from your supplier for better purchase prices. With suppliers on Alibaba, you can often save 15-30% on larger orders
• Comparing suppliers: Use multiple suppliers and negotiate actively. The Boloo Product Tracker helps you find products with the best margin
• Optimizing logistics costs: Consolidate shipments, choose more efficient shipping routes, and compare freight forwarders for your imports
• Reducing returns: Invest in good product packaging and accurate product descriptions via the Listing Generator AI. Fewer returns = lower effective IWO
• Preventing shrinkage: Ensure good storage and inventory rotation to minimize damaged or expired products

IWO and your tax return

The IWO plays a crucial role in your annual tax return. The tax authorities expect you to correctly include the IWO in your profit and loss account. Important points to consider:

• Consistent valuation method: Choose one inventory valuation method (preferably FIFO or weighted average) and apply it consistently
• Retention obligation: Keep all purchase invoices for at least 7 years as proof of your IWO
• Inventory count: Perform a physical inventory count at least annually to determine your beginning and ending inventory
• Write-down: You can write down unsaleable or damaged inventory to its market value

With automatic invoicing via Boloo, you can automatically keep track of all your purchase and sales invoices, making it much easier to calculate your IWO.

Frequently asked questions about calculating the IWO

What is the difference between IWO and inventory value?

The IWO is the purchase value of the products you have sold. The inventory value is the purchase value of the products you still have in stock. Together, they form the total purchase value of your beginning inventory plus purchases: IWO + ending inventory = beginning inventory + purchases.

How often should I calculate the IWO?

We recommend checking at least monthly. During busy sales periods (like Sinterklaas, Black Friday, and Christmas), it's a good idea to check weekly. The more often you measure, the faster you can adjust if your total revenue or margin is off.

Is the bol.com commission part of the IWO?

No. The bol.com commission is a sales cost and is not part of the IWO. The IWO only includes costs directly related to acquiring and making your products sales-ready.

How do you calculate the IWO with multiple suppliers?

If you buy the same product from different suppliers at different prices, it's best to use the weighted average method. Add up the total purchase value and divide by the total number of units. This gives you a fair average purchase price per item to work with.

Can I calculate the IWO automatically?

Yes. With tools like the Boloo Sales Dashboard, you can set your product costs per item. The dashboard combines your sales data from bol.com with your set purchase costs and automatically calculates your gross profit and margin. This saves you manual calculations and gives you real-time insights into your financial performance.