The zero-price effect

The zero-price effect, popularly known as the power of the word free, is a cognitive bias in which a zero price attracts us far more strongly than the saving of a few crowns would justify. We perceive the difference between one crown and zero as huge, even though mathematically it is a single crown. The word free triggers not only a calculation but also an emotion. A zero price removes the fear of losing out, because surely I cannot lose anything on something that is free. That is exactly why free is one of the most powerful words in all of marketing.

Classification of the cognitive bias

• Cause (Cognitive Bias Codex): Need to act fast
• Mental area: Decision-making and emotional
• Marketing function: Price and value
• Buyer journey: Decision
• Cialdini’s principles: not applicable
• System 1 / System 2: System 1 (fast, automatic)

In a nutshell

• What it is: a zero price attracts far more than the real saving justifies.
• Why we do it: free removes the risk of loss and adds emotion.
• Where you will meet it: free delivery, a free gift with purchase, “buy one, get one free”.
• How to use it: wrap value in the word free instead of an equally large discount.

A real-life story

The behavioural economist Dan Ariely demonstrated this in his 2008 book Predictably Irrational. In an experiment, he sold two chocolates, a luxury Lindt truffle and an ordinary Hershey’s Kiss. When the Lindt cost 15 cents and the Hershey’s cost 1 cent, most people chose the higher-quality Lindt. He then lowered both prices by one cent, so the Lindt cost 14 cents and the Hershey’s was free. Suddenly, most people went for the ordinary Hershey’s. The change was the same for both, one cent, but the word free completely overrode the difference in quality.

You know this from online shops. A basket worth 940 CZK (about 39 EUR) plus 90 CZK (about 3.7 EUR) for delivery puts you off. But an offer of “free delivery on orders over 1,000 CZK (about 41 EUR)” can easily persuade you to add goods worth 100 CZK (about 4.1 EUR) just so you do not have to pay for delivery. You spend more, yet you feel you have saved money.

How the zero-price effect works

Every price carries a small risk that the purchase will not be worth it. Zero erases this risk completely. We feel we cannot lose anything on something free, so we decide without hesitation. The effect is closely linked to loss aversion, because free removes the pain of paying, and to reciprocity, because a free gift makes us feel obliged to give something back.

Use in marketing

1. Free delivery. It works better than a discount of the same amount. “Free delivery” sounds like a win, while a discount only sounds like spending a bit less.
2. A gift with purchase. A small free extra raises the value of the offer and also triggers reciprocity.
3. Buy one, get one free. It often works better than a 50% discount, even though mathematically it is the same.
4. Free trial. A zero price lowers the barrier to entry to a minimum. The endowment effect does the rest.
5. An extra bonus. “An extra month free” feels better than a cheaper plan outright, because it is a gift, not a discount.

How to protect yourself from the zero-price effect

1. Work out the total price. Ask how much you will spend in the end, not how much you “saved” on delivery.
2. Do I need that gift? Buying extra goods just for a free gift is not a saving.
3. Watch out for the free threshold. Topping up your order to reach the free delivery limit often costs you more than the delivery would have.

How it connects with other biases

The word free is so powerful because it combines several biases at once. Take free delivery on orders over 1,000 CZK (about 41 EUR). The zero price is the zero-price effect. The reluctance to “lose” money on delivery is loss aversion. And when a gift also arrives with your order, reciprocity kicks in, along with the urge to give something back to the brand. With free trials, the endowment effect also comes into play, because once you get something for free and use it, you do not want to lose it. That is why free is so quietly effective.

Frequently asked questions

What is the zero-price effect?

A cognitive bias in which a zero price attracts us far more strongly than the real saving justifies, because free removes the risk of loss.

Why does free delivery work better than a discount?

Because the word free feels like a risk-free win, whereas an equally large discount only feels like spending slightly less.

Euro amounts are approximate, converted at the Czech National Bank rate of 24.34 CZK per EUR on 29 October 2026.

Patrik Pilous

I am a marketing strategist and SEO consultant. I love the world of marketing, the internet and AI. I am at my best when planning business growth, setting and executing marketing strategy and optimising websites (SEO, GEO and, above all, sales).