The short answer? No. The long answer? It depends.
The pricetoearnings ratio (P/E ratio) is calculated as a stock's current share price divided by its earnings per share (EPS) for a twelvemonth period (usually the last 12 months, or trailing twelve months (TTM)). Most of the P/E ratios you see for publiclytraded stocks are an expression of the stock's current price compared against its previous twelve months' earnings.
A stock trading at $40/share with an EPS (ttm) of $2 would have a P/E of 20 ($40/$2), as would a stock priced at $20/share with an EPS of $1 ($20/$1). These two stocks have the same pricetoearnings valuation  in both cases investors pay $20 for each dollar of earnings.
But, what if a stock earning $1 per share was trading at $40/share? Now we'd have a P/E ratio of 40 instead of 20, which means the investor would be paying $40 to claim a mere $1 of earnings. This seems like a bad deal, but there are several factors which could mitigate this apparent overpricing problem.
First, the company could be expected to grow revenue and earnings much more quickly in the future than companies with a P/E of 20, thus commanding a higher price today for the higher future earnings. Second, suppose the estimated (trailing) earnings of the 40P/E company are very certain to materialize, whereas the 20P/E company's future earnings are somewhat uncertain, indicating a higher investment risk. Investors would incur less risk by investing in more certain earnings instead of less certain ones, so the company producing those surething earnings again commands a higher price today.
Secondly, it must also be noted that average P/E ratios tend to vary from industry to industry. Typically, P/E ratios of companies in very stable, mature industries which have more moderate growth potential have lower P/E ratios than companies in relatively young, quickgrowing industries with more robust future potential. Thus, when an investor is comparing P/E ratios from two companies as potential investments, it is important to compare companies from the same industry with similar characteristics. Otherwise, if an investor simply purchased stocks with the lowest P/E ratios, they would likely end up with a portfolio full of utilities stocks and similar companies, which would leave them poorly diversified and exposed to more risk than if they had diversified into other industries with higherthanaverage P/E ratios. (To read more on P/E ratios, see Understanding The P/E Ratio and Analyze Investments Quickly With Ratios.)
However, this doesn't mean that stocks with high P/E ratios cannot turn out to be good investments. Suppose the same company mentioned earlier with a 40P/E ratio (stock at $40, earned $1/share last year) was widely expected to earn $4/share in the coming year. This would mean (if the stock price didn't change) the company would have a P/E ratio of only 10 in one year's time ($40/$4), making it appear very inexpensive.
The important thing to remember when looking at P/E ratios as part of your stock analysis is to consider what premium you are paying for a company's earnings today, and determine if the expected growth warrants the premium. Also compare it to its industry peers to see its relative valuation to determine whether the premium is the worth the cost of the investment.
Now that you have an understanding of the P/E ratio in terms of stock valuation, learn how the PEG Ratio can help investors price a company based on its future growth potential in

How do I calculate the P/E ratio of a company?
Find out how to calculate this common valuation ratio and what the results can tell you about a company's performance. Read Answer >> 
How can the pricetoearnings (P/E) ratio mislead investors?
A low P/E ratio doesn't automatically mean a stock is undervalued, just like a high P/E ratio doesn't necessarily mean it ... Read Answer >> 
What does the forward p/e indicate about a company?
Explore the forward price to earnings ratio and learn its significance and how it compares to the traditional price to earnings ... Read Answer >> 
What is the average pricetoearnings ratio in the banking sector?
Explore the price/earnings ratio in regard to the banking industry and learn what the average P/E ratio is for most banking ... Read Answer >> 
What's the difference between absolute P/E ratio and relative P/E ratio?
The simple answer to this question is that absolute P/E, which is the most quoted of the two ratios, is the price of a stock ... Read Answer >> 
What is the difference between forward p/e and trailing p/e?
Understand the difference between the trailing P/E ratio, which is the standard pricetoearnings calculation, and the forward ... Read Answer >>

Investing
Is Stock With a Lower P/E Always A Better Choice?
Is a stock with a lower P/E always a better investment than a stock with a higher one? The short answer is no, but it depends on a few things. 
Investing
Beware False Signals From The P/E Ratio
The P/E ratio is a simple tool for evaluating a company, but no one ratio can tell the whole story. 
Investing
Comparing the P/E, EPS And Earnings Yield
Here are three ratios that help investors value stock returns. 
Investing
Can Investors Trust The P/E Ratio?
The P/E ratio is one of the most popular stock market ratios, but it has some serious flaws that investors should know about. 
Trading
How To Use The P/E Ratio And PEG To Tell A Stock's Future
While the pricetoearnings ratio is commonly used for assessing stock prices, the price/earningstogrowth ratio offers forecasting advantages that investors need to know. 
Markets
Getting On The Right Side Of The P/E Ratio Trend
Buying at the right time is crucial, but how do we know when that is? 
Markets
How Do I Calculate the PriceEarnings Ratio?
If Apple is trading at $108.73 per share, and its trailing twelve months' EPS is $6.45, calculate the P/E ratio as... 
Investing
Differences Between Forward P/E And Trailing P/E
The most common types of price to earnings ratios are forward P/E and trailing P/E. Find out how they differ and the advantages and drawbacks of each. 
Investing
Explaining Forward PricetoEarnings Ratio
The estimated P/E of a company is often used to compare current earnings to estimated future earnings. 
Investing
The 4 Basic Elements Of Stock Value
Investors use these four measures to determine a stock's worth. Find out how to use them.

PriceEarnings Ratio  P/E Ratio
The PricetoEarnings Ratio or P/E ratio is a ratio for valuing ... 
P/E 30 Ratio
The pricetoearnings (P/E) ratio is the valuation ratio of a ... 
Forward Price To Earnings  Forward P/E
A measure of the pricetoearnings ratio (P/E) using forecasted ... 
Trailing PriceToEarnings  Trailing P/E
The sum of a company's pricetoearnings, calculated by taking ... 
P/E 10 Ratio
A valuation measure, generally applied to broad equity indices, ... 
Ratio Analysis
A ratio analysis is a quantitative analysis of information contained ...