The Valuation Conundrum: P/E Ratio vs. P/S Ratio

Did you buy a stock with low P/S ratio and make a loss? Most investors fall prey to the valuation conundrum. Here’s how to read these ratios.

“Price is what you pay; value is what you get.” It’s a lesson Warren Buffett learned from Ben Graham. But there is more to this sentence than you think. Most often, new investors confuse value stocks with those whose stock prices have fallen significantly or are oversold. While these measures help shortlist value stocks, price-to-earnings (P/E) and price-to-sales (P/S) ratios are other parametres to identify undervalued stocks. 

In this article, I will solve the valuation conundrum of the P/E or P/S. 

The valuation conundrum 

As an equity shareholder, look at a stock like a business owner, and everything will fall into place. As a business owner, if you were to earn $1 million in profit, you could 

  • Either sell 5,000 products for a net profit of $200/product; or 
  • Sell 200 products for a net profit of $5,000/product. 

When does the P/S valuation matter? 

The first point above is the business of volume, where sales matter more than profit. In that business, you need to look at the P/S ratio. Some volume-driven businesses are retailers like Loblaw and software-as-a-service companies like Lightspeed Commerce (TSX:LSPD)(NYSE:LSPD).

Loblaw and Lightspeed have P/S ratios of 0.71 and 5.72, respectively. The huge difference is because of their size. Loblaw is already a market leader in grocery and has a revenue growth rate of around 2%. Lightspeed is a fast-growing omnichannel commerce platform with a revenue-growth rate of over 100%. Excluding acquisitions, it had average organic revenue growth of 51%, and it expects this rate to slow to 35% in the next five years. A 5.72 P/S ratio is cheap for a 35% revenue growth rate company. It is also below Shopify’s P/S ratio of 8.6. 

As these companies become market leaders, their P/S ratio falls, and their P/E ratio grows. Because once these companies achieve the sales threshold, they tend to become profitable. I will elaborate. In the first scenario, the company aims to earn $1 million by focusing on the 5,000 sales volume. The secondary focus is profit. The company aims to increase profit per sale to $200 or more.

Lightspeed Commerce and Shopify are value stocks based on the P/S ratio. These stocks are not capital-intensive and don’t have a huge debt burden, allowing them to scale. Their P/E ratios matter when they become large-cap stocks with market share and limited revenue growth. 

When does the P/E valuation matter? 

The second scenario focuses on reaching the $1 million target through higher profits. That is where the P/E ratio matters the most. For instance, Descartes Systems (TSX:DSG)(NASDAQ:DSGX) and Magna International (TSX:MG)(NYSE:MGA) have large companies, as their clients and securing these clients take longer. But once these clients come on board, they sign long-term contracts and generate significant profit. Hence, their net income grows faster than revenue. 

Descartes and Magna have trailing P/E ratios of 58.3 and 13.5, respectively. Descartes’s net income surged 26%, while its sales surged 18% in the first quarter. Magna’s EPS fell 40%, while its sales fell 5% in the first quarter. This growth is reflected in the ratio. Descartes’s ratio states that for $80 per share price, you are getting the value of 1/58th the current EPS. This value will reflect in the long term, as you get access to all future EPS and dividends the company pays till you sell the stock. 

Still, the two stocks are undervalued as their sales growth slowed. If sales grow, their EPS will grow faster, making the current stock price look like a bargain. Descartes’s valuation looks like a bargain compared to its peer Kinaxis’s P/E ratio of 212. 

Beyond the P/E and P/S ratios 

When determining which stock to buy, you should look at other factors, like the news, the company’s business, the growth outlook, and the macro environment. The P/E and P/S ratios only tell you if the stock price is inflated or cheap depending on current fundamentals.

The Motley Fool has positions in and recommends Shopify. Fool contributor Puja Tayal has no position in any of the stocks mentioned. The Motley Fool recommends DESCARTES SYS, KINAXIS INC, Lightspeed Commerce, and Magna Int’l.

More on Stocks for Beginners

woman gazes forward out window to future
Energy Stocks

1 Dividend Stock Down 17% That’s an Amazing Lifetime Buy

Northland Power has already taken its dividend medicine, and the lower price could set up a long-term comeback.

Read more »

Real estate investment concept with person pointing on growth graph and coin stacking to get profit from property
Dividend Stocks

A Practical Way to Use Your TFSA to Generate $300 a Month – Tax-Free

Generate $300 a month in tax‑free TFSA income using a balanced mix of stocks such as this high-yielding trio.

Read more »

diversification is an important part of building a stable portfolio
Dividend Stocks

3 Dividend Stocks I Believe Belong in Almost Every Investor’s Portfolio

These dividend stocks are well-suited for most long-term portfolios, especially when accumulated on market dips.

Read more »

motley fool stocks to buy april 2026
Stocks for Beginners

Just Released: 5 Top Motley Fool Stocks to Buy in April 2026

All of these stocks are cheaper than they were not too long ago.

Read more »

the word REIT is an acronym for real estate investment trust
Dividend Stocks

Forget Risk, All Investors Need is This Consistent 5.6% Dividend Stock

Dream Industrial is quietly growing cash flow and paying a 5%+ yield, even while refinancing gets tougher.

Read more »

Map of Canada with city lights illuminated
Dividend Stocks

The Only Stock I’d Hold in a TFSA for Life

A look at the one stock to hold in a TFSA for life, offering stability, dividends, and long‑term reliability.

Read more »

senior relaxes in hammock with e-book
Dividend Stocks

A 7% Dividend Stock Ideal for Passive Income Seekers

Canoe EIT Income Fund offers a 7%-plus yield and monthly payouts by spreading income across a diversified portfolio.

Read more »

ETF is short for exchange traded fund, a popular investment choice for Canadians
Dividend Stocks

3 Canadian ETFs Soaring Upwards to Buy Now for a TFSA

These three BMO index ETFs can turn a TFSA into a simple global portfolio that compounds tax-free.

Read more »