Left-digit effect

The left-digit effect, also known as psychological pricing or charm pricing, is a cognitive bias in which we judge a price mainly by its first digit from the left. That is why 199 CZK (about 8.2 EUR) seems much cheaper than 200 CZK (about 8.2 EUR), even though the difference is a single crown. The brain does not process the whole price; it rounds it based on the first number it sees. A nine at the end is therefore no accident but one of the oldest and most widely used pricing tricks in the world, and you come across it every day in every shop.

Classification of the cognitive bias

• Cause (Cognitive Bias Codex): Too much information
• Mental domain: Decision-making and perception
• 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: we read a price by its first digit, so we perceive 199 as “one hundred and something”.
• Why we do it: the brain rounds the price and saves energy.
• Where you see it: prices ending in 9, 99 or 90 almost everywhere.
• How to use it: for budget-sensitive prices, choose endings with a nine.

A real-life story

Researchers Manoj Thomas and Vicki Morwitz from Cornell University described this in a 2005 study in the Journal of Consumer Research. They showed that people perceive a price of $2.99 as significantly lower than $3.00, far more than a one-cent difference would justify. The brain stops at the first digit and estimates the size from it. A two at the start simply means “two and something”, even though it is almost three.

It has become so ingrained that prices without a nine now seem almost suspicious to us. When you see a flat 200 CZK (about 8.2 EUR) in a shop, it looks more expensive and contrived. 199 CZK (about 8.2 EUR), on the other hand, looks like a carefully calculated, good-value price. Yet it is only one crown cheaper.

How the left-digit effect works

Reading from left to right means the first digit carries the most weight in our estimate. With a price of 199, the brain registers the one first and anchors itself at a value of around a hundred. Only then does it read the rest, but by that point the first impression is already formed. The effect is related to anchoring, because the first number sets the reference point, and to framing, because the same price can be presented so that it seems lower.

Use in marketing

1. Nine endings for everyday goods. For price-sensitive products, 199, 299 or 1,990 seem much cheaper than a round number.
2. A crossed-out price and a new nine. Combining an anchor with the left digit, for example from 2,499 to 1,999, multiplies the sense of a bargain.
3. Choosing the right threshold. Moving from 300 to 299 often works better than from 290 to 289, because it changes the first digit.
4. Round prices for premium products. For luxury goods, a round number pays off instead. It looks confident and does not shout “discount”, which fits with the Veblen effect.
5. Test price thresholds. A small price shift across a digit boundary can move conversions more than a large discount.

How to guard against the left-digit effect

1. Round the price up. Read 199 as 200 and decide whether it is worth it to you.
2. Count the total. For bigger purchases, add up the real amounts, not your impressions of the nines.
3. Do not be fooled by the threshold. The difference between 299 and 300 is one crown, not “a whole hundred”.

How it combines with other biases

The left-digit effect is often just the first layer of a pricing trick. Take a crossed-out price in an online shop that used to be “2,499 CZK (about 100 EUR)” and is now “1,999 CZK (about 82 EUR)”. The crossed-out price works as an anchor against which you measure the new price. The nine ending of 1,999 then, through the left digit, comes across as “one thousand and something” rather than almost two thousand. And the whole thing is framed as “you save 500 CZK (about 21 EUR)”, which uses framing. Three biases, one price tag.

Frequently asked questions

What is the left-digit effect?

A cognitive bias in which we judge a price mainly by its first digit from the left, so we perceive 199 as much cheaper than 200.

Why do prices end in 9?

Because a nine ending keeps the first digit low, so the price seems cheaper than it really is. This is known as psychological pricing.

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).