One of the best investments we can make is in our own knowledge and skill set. With that in mind, this article will work through how we can use Return On Equity (ROE) to better understand a business. We'll use ROE to examine Quanex Building Products Corporation (NYSE:NX), by way of a worked example.

Quanex Building Products has a ROE of 4.5%, based on the last twelve months. One way to conceptualize this, is that for each $1 of shareholders' equity it has, the company made $0.045 in profit.

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How Do You Calculate Return On Equity?

The formula for return on equity is:

Return on Equity = Net Profit ÷ Shareholders' Equity

Or for Quanex Building Products:

4.5% = US$18m ÷ US$390m (Based on the trailing twelve months to January 2019.)

Most know that net profit is the total earnings after all expenses, but the concept of shareholders' equity is a little more complicated. It is the capital paid in by shareholders, plus any retained earnings. You can calculate shareholders' equity by subtracting the company's total liabilities from its total assets.

What Does ROE Mean?

ROE looks at the amount a company earns relative to the money it has kept within the business. The 'return' is the amount earned after tax over the last twelve months. A higher profit will lead to a higher ROE. So, all else equal, investors should like a high ROE. That means it can be interesting to compare the ROE of different companies.

Does Quanex Building Products Have A Good Return On Equity?

By comparing a company's ROE with its industry average, we can get a quick measure of how good it is. Importantly, this is far from a perfect measure, because companies differ significantly within the same industry classification. If you look at the image below, you can see Quanex Building Products has a lower ROE than the average (14%) in the Building industry classification.

That certainly isn't ideal. We'd prefer see an ROE above the industry average, but it might not matter if the company is undervalued. Still, shareholders might want to check if insiders have been selling.

Why You Should Consider Debt When Looking At ROE

Companies usually need to invest money to grow their profits. That cash can come from issuing shares, retained earnings, or debt. In the first two cases, the ROE will capture this use of capital to grow. In the latter case, the use of debt will improve the returns, but will not change the equity. Thus the use of debt can improve ROE, albeit along with extra risk in the case of stormy weather, metaphorically speaking.

Combining Quanex Building Products's Debt And Its 4.5% Return On Equity

Quanex Building Products has a debt to equity ratio of 0.59, which is far from excessive. Its ROE is quite low, and the company already has some debt, so surely shareholders are hoping for an improvement. Judicious use of debt to improve returns can certainly be a good thing, although it does elevate risk slightly and reduce future optionality.

But It's Just One Metric

Return on equity is a useful indicator of the ability of a business to generate profits and return them to shareholders. A company that can achieve a high return on equity without debt could be considered a high quality business. If two companies have around the same level of debt to equity, and one has a higher ROE, I'd generally prefer the one with higher ROE.

But when a business is high quality, the market often bids it up to a price that reflects this. It is important to consider other factors, such as future profit growth -- and how much investment is required going forward. So you might want to check this FREE visualization of analyst forecasts for the company.

Of course, you might find a fantastic investment by looking elsewhere. So take a peek at this free list of interesting companies.

We aim to bring you long-term focused research analysis driven by fundamental data. Note that our analysis may not factor in the latest price-sensitive company announcements or qualitative material.

If you spot an error that warrants correction, please contact the editor at editorial-team@simplywallst.com. This article by Simply Wall St is general in nature. It does not constitute a recommendation to buy or sell any stock, and does not take account of your objectives, or your financial situation. Simply Wall St has no position in the stocks mentioned. Thank you for reading.