How to know what price to pay for a stock

A price is only good or bad compared to something. The market price tells you what other people are paying today. It does not tell you what the business is worth. So “is $323 a good price for Apple?” cannot be answered until you have a second number to hold it against.

Most of the advice you will find skips this. “Buy on a down day.” “Wait for the 52-week low.” “Watch the 200-day moving average.” Those all compare the price to itself, in the past. A stock can be at a 52-week low and still be worth half of that. It can be at an all-time high and still be a bargain.

The second number you need is fair value. Everything below is about getting it and using it.

Step 1: Is the business worth owning at any price?

Before price, quality. Check four things over the last ten years, not the last quarter:

• Return on invested capital (how much profit the business earns on the money put into it). Great businesses clear 15% year after year.
• Growth in earnings per share, revenue, and free cash flow. Steady beats spectacular.
• Debt. Could it pay off its long-term debt with a few years of earnings?
• Consistency. No big gaps, no years that need explaining away.

If a company fails this, stop here. Screeners find cheap. They do not find worth owning. A cheap stock on a fading business is what the value investing world calls a value trap, and no buy price fixes it. The four pillars guide walks through each check.

Step 2: What is it worth?

Now estimate fair value. The simplest honest way is this: take the earnings the business produces, guess how fast they will grow, and ask what that stream of future earnings is worth today at the return you want. That is a discounted cash flow, and the DCF for beginners guide does it with a worked example.

Two rules keep the estimate honest:

• Use the company's own track record for the growth guess, not analyst forecasts. The last ten years are evidence. Next year's forecast is a hope.
• Cap the growth rate. Even a business growing 25% a year cannot do that for a decade. Something like 15% is the most anyone should assume.

You will get a number. It is an estimate, and two careful people will get different estimates from the same filings. That is normal. If you want to see how much the estimates can spread, this comparison of four public calculators shows a $156 gap on one company on one day.

Step 3: How wrong can you afford to be?

Your fair value will be off. You do not know by how much or in which direction. So you do not pay fair value. You pay fair value minus a margin of safety, which is a discount sized to how uncertain the business is.

• Stable, predictable business with a long record: a 25% to 40% discount.
• Harder to predict: 50% or more.
• A common default in value investing is 50%.

The margin of safety guide has the formula and the reasoning. The short version: buy far enough below your own estimate that you can be wrong about growth and still be fine.

Step 4: Your buy-below price

Buy-below price = fair value × (1 − margin of safety)

That is the number you were looking for. It is the answer to “what price should I buy at.” Not a prediction of where the stock will go. A line under which the deal is good enough for you, given what you know.

Write it down. Then wait.

Real numbers from Apple's FY2025 statements, run through the method above. The full value check is in is Apple undervalued?.

So Apple, by this method, is a great business at a price roughly four times what a conservative value investor would pay today. That is not a prediction that it will fall. It is a statement that today's price leaves no room to be wrong. A less strict investor might use a 30% margin and land near $114. Either way the answer is the same: not yet.

Two other conservative prices from the same numbers, in case you like a second opinion: the price at which Apple's owner earnings would pay you 10% a year is about $70, and the price you would recover from cumulative cash flow in eight years is about $97. Three methods, one message.

They answer a different question. They tell you whether the price is low compared to its own recent history. Useful for timing an order once a stock is already under your buy-below price. Useless for deciding whether the business is worth what it costs.

The Reddit favourite “there is no bad price for a great company if you hold long enough” is half right. A great company bought at four times fair value can take a decade to grow into its price, and you earn nothing while it does. Quality gets you a company worth waiting for. Price decides whether the wait pays.

The hard part is not the math. It is sticking to the number when the stock is 20% above it and the news is good.

The cleanest fix is to turn the buy-below price into zones and let a tool watch them for you:

• Buy zone: at or below your buy-below price.
• Watch zone: approaching it.
• Sell zone: the price has run far above fair value.

Wonderfolio does this automatically. It runs the quality check, estimates fair value from the company's track record, derives the zones from that fair value, and flags when a price crosses into one. The zones come from the numbers, not from a setting. The decision is always yours. If you want to see one company run through it, the free report does exactly that for a ticker of your choice.

Or run it by hand with the free calculators. The method is the same either way.