What Are Complementary Goods? Definition, Examples & Impact on Sales Strategy
Published on October 6, 2025
• 8 min read
Complementary goods are products used together, where the demand for one increases the demand for the other, for example, printers and ink cartridges, coffee machines and coffee pods.
They directly link complementary goods supply and demand, meaning a price drop in one often boosts sales of its complement. Businesses use this relationship to effectively plan pricing, inventory, and cross-selling strategies.
This blog explains complementary goods, their types, and how they impact market demand to help you understand their role in driving consumer behaviour and business growth.
- Understanding Complementary Goods
- Types of Complementary Goods & How They Work
- Where to Show Complementary Products?
- Difference Between Complementary and Substitute Goods
- Cross Price Elasticity of Complementary Goods
- The Impact of Complementary Goods on Market Demand
- Driving Growth with WareIQ’s Complementary Fulfilment Solutions
- FAQs
Understanding Complementary Goods
What are complementary goods? They are products that create additional value when consumed together. A rise in demand for one directly increases the demand for its complement.
For example, when mobile phone sales increase, the need for chargers, cases, or headphones also rises. Similarly, a drop in the price of gaming consoles often boosts sales of exclusive games and accessories.
Complementary goods often share a linked pricing pattern. If the price of one decreases, both its demand and the demand for its complement typically grow.
They cannot be sold separately → False. Many still sell independently.
All complementary goods are equally dependent → False. Some have stronger demand ties than others.
Types of Complementary Goods & How They Work
When understanding what complementary goods are, it’s important to know they vary in strength. The types of complementary goods are broadly classified into strong complements and weak complements, based on how closely their demand is tied together.
Strong Complementary Goods?
Strong complementary goods, also called perfect complements, have an almost inseparable demand relationship. When the price of one decreases, the demand for the other rises continuously without plateauing.
They are often irreplaceable, meaning one cannot function without the other. For example, without ink cartridges, a printer is useless.
Strong complementary goods examples:
- Cars and gasoline
- Printers and ink cartridges
- Cameras and memory cards
- Coffee machines and coffee pods
Weak Complementary Goods?
Weak complementary goods, or near complements, share a demand link but with flexibility. While a price drop in one product increases demand for its complement, the effect is weaker as there are multiple alternatives.
For instance, cheaper charcoal increases the demand for steaks but also spreads demand across other grillable foods.
Examples of weak complementary goods:
- Charcoal and steaks
- Tennis rackets and tennis balls
- Smartphones and optional accessories like stands or selfie lights
- Bread and various spreads (butter, jam, peanut butter)
Where to Show Complementary Products?
Displaying complementary products effectively supports cross-selling strategies. By showing the right items at the right time, you can enhance the shopping experience and increase e-commerce revenue.
Personalised recommendation engines can highlight complementary products in multiple areas of an online store. Research shows the highest revenue potential lies in:
- Product pages
- Pop-ups on unavailable product pages
- Pop-ups after adding to cart
- Store home page
- Shopping cart
- Blog articles
For complementary goods, the most effective placements are:
- On product pages → presenting relevant add-ons or related items.
- Pop-ups after adding to cart → capturing attention at a critical decision-making stage.
This timing ensures that customers see relevant suggestions at the exact moment they’re most likely to make a purchase, maximising both convenience and sales potential.
Difference Between Complementary and Substitute Goods
Complementary goods are products or services that enhance a customer’s willingness to pay (WTP) for another product. For example, a printer is of little use without ink cartridges, and razors require blades to function. These products rely on one another, making them true complements.
Substitute products, in contrast, reduce a customer’s WTP for another product or service. For instance, digital communication tools can serve as a substitute for traditional postal services, thereby reducing demand for paper and stamps.
| Complementary Goods | Substitute Goods |
| They work together, enhancing the value of each other. | They work as alternatives, replacing the need for one another. |
| Demand for one good increases when the demand or affordability of its complement rises. | Demand for one good decreases when the demand or affordability of its substitute rises. |
| Printers and ink cartridges, cars and petrol, razors and blades. | Butter and margarine, tea and coffee, email and postal services. |
| A price drop in one product typically leads to an increase in demand for its complement. | A price drop in one product typically leads to a decrease in demand for its substitute. |
| Can create synergies and expand markets. Example: gaming consoles are boosting demand for exclusive games. | It can create competition within a market. Example: streaming services reducing demand for DVDs. |
| Often leveraged for cross-selling and building product ecosystems (e.g., smartphones + accessories). | Used to capture market share by offering alternatives (e.g., plant-based milk vs dairy milk). |
| Often stable, but may evolve with new technologies. | More likely to shift as innovation creates better alternatives. |
| Increases overall value for both products when combined. | Creates value by offering a cheaper, better, or more convenient alternative. |
Cross Price Elasticity of Complementary Goods
Cross-price elasticity measures how the demand for complementary goods responds to a price change in a related product. If the price of one item decreases, the demand for its complement typically rises.
Understanding how complementary goods behave helps businesses develop effective pricing strategies and manage their inventory. For example, lowering printer prices boosts demand for ink and toner, increasing overall revenue.
By understanding cross-price elasticity, retailers can optimise pricing, predict demand patterns, and strengthen their competitive advantage.
Three key product relationships define complementary goods supply and demand:
- Substitute Products: Compete for the same customers, such as those in the tea and coffee industries. A price rise in one increases demand for the other.
- Complementary Products: Consumed together, like printers and ink cartridges. A price drop in one increases demand for the other.
- Unrelated Products: No effect on each other’s consumption, such as bread and batteries.
The Impact of Complementary Goods on Market Demand
The global complementary goods market, particularly in electronics accessories such as chargers, headphones, and protective cases, is experiencing rapid expansion. For example, according to Grand View Research, the global electronic accessories market size was valued at USD 171.20 billion in 2024 and is projected to reach USD 276.40 billion by 2033.
The effect of price change on complementary goods is direct and significant. When the price of one product falls, consumers are more likely to purchase its complement. For example, a drop in the price of coffee machines drives higher demand for coffee pods.
How Complementary Goods Influence Demand
Price Elasticity
The demand for complementary goods is often highly elastic. Even a slight price reduction in one product can lead to a noticeable increase in its complement’s sales. For instance, lower fuel prices may boost demand for fuel-intensive vehicles.
Cross-Promotion Strategies
Businesses use complementary goods supply and demand to cross-promote products. Gyms, for example, may offer discounts on classes to members purchasing annual subscriptions.
In eCommerce, retailers often focus on product bundling to encourage customers to purchase related products together, increasing both revenue and customer value.
Innovation and Technology
Advancements in one product create markets for its complements. High-definition TVs increased demand for HD content and cable services.
Consumer Preferences
Shifting tastes can reshape demand. Rising health awareness has increased interest in both gym memberships and wellness apps.
Market Research
Firms study complementary goods demand to forecast trends and optimise inventory management. To better understand how these relationships fit into the broader product landscape, explore the different types of goods and how they impact consumer demand.
Regulatory Impact
Government policies influence demand. Stricter emission rules boost electric vehicle sales, increasing the need for charging stations.
Economic Factors
Economic slowdowns reduce spending on luxury products and their complements.
Suggested – Managing Goods in Transit: Best Practices and Challenges
Driving Growth with WareIQ’s Complementary Fulfilment Solutions
Understanding the complementary goods supply and demand relationship is crucial for scaling in today’s competitive eCommerce landscape. Just as the demand for one product boosts its complement, WareIQ enables brands to maximise this synergy through seamless multi-channel fulfilment and intelligent inventory planning.
With a Pan-India network across 12+ cities and last-mile delivery spanning 27,000+ pin codes, WareIQ ensures your products and their complementary goods reach customers faster and more efficiently.
Its plug-and-play integrations with leading marketplaces like Amazon, Flipkart, and Myntra, along with D2C platforms like Shopify and WooCommerce, allow businesses to unify fulfilment across multiple channels while reducing operational complexity.
The AI-powered Inventory LogIQ solution further optimises stock levels, minimising stockouts of both primary and complementary products. Additionally, WareIQ’s tech-enabled returns QC safeguards against claim rejections and enhances customer trust.
Related – Types of Goods: From Consumer Products to Industrial Goods
FAQs
What happens if the price of a complement increases?
If the price of a complement increases, the demand for its paired product usually decreases because consumers are less likely to buy one without the other.
How do prices and markets change with complementary goods?
Prices and markets for complementary goods are closely linked. When the price of one good drops, demand for its complement usually rises. Conversely, a price increase in one can reduce demand for both, affecting market dynamics.
What is the elasticity of demand for complements?
The elasticity of demand for complements is negative, meaning that when the price of one good rises, the demand for its complement falls. The closer the relationship between the two goods, the more elastic (responsive) the demand becomes.
