Black Friday Could Cost You More Than You Earn: 4 Mistakes That Eat Into E-Commerce Profits

Black Friday, taking place on November 27, will be one of the most important sales days of the year for many e-commerce businesses. Advertising budgets are increasing, discounts are being planned, and sales growth often becomes the main measure of success. However, higher revenue does not necessarily mean higher profits. In fact, the opposite can happen: a business may sell more than usual but earn less.

Competition for shoppers' attention will once again be intense this year. According to Adobe's forecast published in late September, US online holiday sales are expected to reach $275.1 billion in November and December 2026, representing a 6.7% increase compared to last year.

While these figures reflect the US market, they also highlight a broader trend: sales events are becoming longer, and competition for customers begins well before Black Friday itself.

In this environment, e-commerce businesses need to prepare not only for an increase in orders but also to assess how much profit those orders will actually generate. Here are four mistakes that can undermine Black Friday campaign profitability – and how to avoid them.

1. You Keep Increasing Your Advertising Budget Even When Additional Sales Are No Longer Profitable

During Black Friday, advertising campaign results can look impressive. More visitors, more orders, higher revenue. When consumer interest is high, increasing the advertising budget may seem like the obvious way to capitalise on demand.

However, advertising efficiency is not constant. The first few thousand euros spent on advertising may reach people who are already familiar with the brand or actively searching for a specific product. As the budget increases, ads may begin reaching less interested audiences, making each additional sale more expensive.

The problem arises when businesses continue increasing their budgets simply because total campaign revenue is growing.

For example, imagine that an additional €1,000 in advertising generates €3,000 in sales. At first glance, this looks like a good result. However, if only €700 remains after discounts, product costs and variable order expenses, the additional investment does not pay off.

What should you do?

Before launching the campaign, calculate the maximum amount you can afford to pay for an order and the minimum return on advertising spend required to make that sale profitable.

You should also establish clear criteria for when to increase the budget and when to stop spending. A high volume of orders alone is not a sufficient reason to invest more in advertising.

During Black Friday, the goal should not be to spend as much of the planned budget as possible. It should be to understand whether each additional euro invested in advertising still generates enough value.

2. Your ROAS Looks Great but Does Not Reflect Actual Profitability

ROAS (Return on Ad Spend) is one of the most widely used advertising performance metrics. It shows how much sales revenue is generated for every euro spent on advertising.

However, ROAS does not tell you how much profit remains from that revenue.

Let's say a campaign achieves a ROAS of 5. This means that, according to the advertising platform's attribution, every euro spent on advertising generates €5 in revenue. The result may look excellent, but its actual value depends on product margins, discounts, delivery costs and other expenses.

Another important consideration is that advertising platforms do not always measure conversions in the same way. Google Ads, Meta Ads and analytics systems may attribute the same sale to different advertising campaigns.

This becomes particularly relevant during Black Friday, when shoppers frequently interact with multiple advertising channels, compare offers and return to the same online store several times before making a purchase.

What should you do?

Compare advertising platform data with your online store's actual results. Look beyond ROAS and evaluate the number of orders, net sales revenue after discounts and returns, product margins and other variable costs.

It is also worth separating purchases made by new customers from those made by returning customers. A campaign that generates a large number of sales from existing customers does not necessarily create as much additional value as the platform's reporting suggests.

A strong ROAS is a useful indicator. However, it should not be the only factor used to determine whether a sales campaign was successful.

3. You Focus Entirely on Black Friday, Even Though Shoppers Make Decisions Earlier

Black Friday has long ceased to be a one-day shopping event. Many retailers begin announcing offers in early November, giving consumers more time to compare prices, products and online stores.

According to Adobe, US online sales on Black Friday 2025 increased by 9.1% year over year, reaching $11.8 billion. Meanwhile, Cyber Monday sales grew by 7.1%. This difference is also linked to shoppers increasingly taking advantage of deals available earlier in the season.

For businesses, this means that waiting until Black Friday itself to start attracting new customers may be too late – or too expensive.

If someone discovers your brand for the first time on November 27, they still need to evaluate the product, compare prices and delivery conditions, and decide whether they trust your store. In contrast, a shopper who became familiar with the product earlier may have already made most of their purchasing decision before the sale begins.

What should you do?

Divide your campaign into several stages. Before the busiest sales period, introduce potential customers to your products, their benefits and the offers you plan to provide.

As Black Friday approaches, focus more attention on consumers who have already shown interest. During the main promotional days, prioritise clear purchasing incentives and a convenient shopping experience.

However, this does not mean automatically shifting your entire advertising budget to an earlier period. It is important to understand which audiences tend to make spontaneous purchases and which need more time to decide.

The goal is not to advertise for as long as possible. It is to avoid trying to fit the entire customer decision-making process into a single day.

4. You Measure Sales Revenue but Forget What Happens After Black Friday

Once Black Friday is over, businesses typically begin by reviewing a few key metrics: the number of orders received, total revenue generated and advertising costs. However, some expenses and final results only become clear later.

Product returns are one example. Significant discounts may encourage shoppers to order more products or make quicker purchasing decisions. If some of those products are subsequently returned, actual campaign revenue decreases, while logistics and order administration generate additional costs.

Another important consideration is customer value beyond the first purchase.

If you acquire 1,000 new customers during Black Friday, their value should not be measured solely by their initial orders. Some may never return, but others could make repeat purchases, choose more expensive products or eventually become loyal customers.

This is where the difference between a temporary sales spike and long-term business value becomes apparent.

What should you do?

After Black Friday, evaluate not only the revenue recorded during the campaign but also subsequent product returns and final profitability.

New customers should be analysed separately. How many make a repeat purchase? What is the value of their second order? How much did it cost to acquire them?

If possible, compare the behaviour of customers acquired during Black Friday with that of customers who purchased during regular trading periods.

This will help you understand whether the campaign created sustainable business value or simply generated a temporary increase in revenue.

How Can You Tell Whether Black Friday Was Actually Successful?

High revenue, growing order volumes and impressive-looking advertising reports do not necessarily mean that a campaign was profitable.

When evaluating results, businesses should ask several questions:

• How much profit remained after discounts?
• How much did it cost to generate additional sales?
• What proportion of orders came from new customers?
• How much value could those customers generate in the future?

Ultimately, it is important to compare not only Black Friday itself but also performance over a longer period. If some customers simply brought forward purchases they would otherwise have made in December, record-breaking November revenue may not tell the whole story.

That is why, before November 27, the most important question is not how large a discount you can offer or how much extra you can spend on advertising.

A far more useful approach is to know in advance how much you can afford to spend, how much you need to earn, and at what point additional sales stop being profitable for your business.

That should be the real measure of a successful Black Friday campaign.