$Tesla(TSLA.US)$ stock is poised to open above $1,200 a share, putting it close to its all-time high of $1,243.49. As the stock rises -- it soared by double digits on Monday -- expect more debate about how to value shares of the EV leader.

Wall Street, for its part, appears to believe the stock is worth roughly 100 times Tesla's per-share earnings. That is about 10 times more valuable than stocks of traditional auto makers, but it seems about right, based on one valuation methodology.

In premarket trading on Tuesday, Tesla stock was up 0.6% at $1,206.95, while futures on the S&P 500 and Dow Jones Industrial Average were both up about 0.3%. The shares gained 13.5% on Monday after the company reported that it delivered more than 308,000 vehicles in the fourth quarter, roughly 15% more than the roughly 267,000 Wall Street expected.

At about $1,207 a share, and with about 1 billion shares outstanding, Tesla is valued at about $1.2 trillion -- an eye-popping valuation, especially for a car maker.

The price is about 130 times the relatively outdated Wall Street consensus forecast of about $9 a share in 2022 earnings. $Ford Motor(F.US)$, by comparison, is valued at about 11 times, while $General Motors(GM.US)$ is at about nine times.

Behind the gap is the fact that traditional car companies like Ford and GM haven't grown the way Tesla is expanding now in many generations. Tesla's delivery volumes rose about 87% in 2021.

More deliveries at Tesla means more earnings. And as Wall Street has responded to Tesla's latest news on deliveries, disclosed Sunday, the consensus call on 2022 earnings has gone up by about 20 cents a share over the past couple of days. The average forecast for Tesla's stock price, meanwhile, has increased by about $20, to roughly $863 a share.

An increase of $20 in the target for the stock price for 20 additional cents in per-share earnings is a multiple of 100 times -- a rule of thumb investors can use in tackling the novel challenge of valuing a rapidly growing car company.

Simply plug in the consensus call for 2022 earnings estimates and multiply by 100. By that logic, to justify the $1,200 price Tesla would need to earn $12 a share in 2022. The current consensus estimate is $9, but the figure is based on part on forecasts that are out of date: Not every analyst raises estimates at the same rate, or in response to every tidbit of news.

Early this past year, analysts expected Tesla to earn about $4 a share in 2021, but the actual figure is likely to come in at more than $6. Earnings estimates rise when things are getting better, as they have been for Tesla lately.

The 2021 experience makes a per-share profit of $12 look possible. If Tesla hits that number, it would represent growth in earnings of roughly 100%. At a stock price of $1,200, the price/earnings ratio would be 100 times. Divide that by the growth rate, at 100%, and you get a price-to-earnings-to-growth ratio of about 1.

There is no right PEG ratio: What figure makes sense depends on the company, the industry, and the growth rate. But a PEG of 1 isn't all that excessive. The PEG ratio of the Russell 1000 Growth Index is roughly 2 to 3 times.

Whatever the multiple Tesla trades for, investors can be sure bulls and bears will debate it. Investors can also be sure that the stock will go higher if the company manages to keep beating delivery estimates by double-digit percentages, as it did in the fourth quarter.