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

Dividend Stocks

Got $7,000? Where to Invest Your TFSA Contribution in 2026

Putting $7,000 to work in your 2026 TFSA? Consider BMO, Granite REIT, and VXC for steady income, diversification, and long-term…

Read more »

some REITs give investors exposure to commercial real estate
Dividend Stocks

The Ideal Canadian Stock for Dividends and Growth

Want dividends plus steady growth? Power Corporation offers a “quiet compounder” mix of cash flow today and patient compounding from…

Read more »

AI concept person in profile
Tech Stocks

TFSA Wealth Plan: Create $1 Million With a Single Canadian Stock

Topicus could help build a $1 million TFSA thanks to sticky software, recurring revenue, and a disciplined acquisition engine if…

Read more »

Young Boy with Jet Pack Dreams of Flying
Stocks for Beginners

The Smartest Growth Stock to Buy With $1,000 Right Now

This under-pressure growth stock is backed by surging demand, a massive backlog, and a clear runway for expansion in the…

Read more »

Canadian flag
Dividend Stocks

Buy Canadian: These TSX Stocks Could Outperform in 2026

Looking to 2026, three Canadian names pair reasonable valuations with resilient cash flow and structural tailwinds.

Read more »

woman checks off all the boxes
Stocks for Beginners

4 Cheap Canadian Stocks to Buy Right Now With $4,000

Are you looking for some investment ideas for 2026? Here are four Canadian growth stocks I'd buy for the new…

Read more »

shipping logistics package delivery
Dividend Stocks

TFSA Investors: 3 Canadian Stocks to Hold for Life

Want TFSA stocks you can hold for life? These three Canadian names aim for durability, compounding, and peace of mind.

Read more »

Senior uses a laptop computer
Stocks for Beginners

If I Could Only Buy 3 Stocks in the Last Month of 2025, I’d Pick These

As markets wrap up 2025, these three top Canadian stocks show the earnings power and momentum worth holding into next…

Read more »