The price of stock depends on one thing: demand. If the price goes up, then demand for the stock is going to follow and vice versa. Every day a stock either goes up, down or sideways (no change). The price change will usually be more dramatic over longer time periods. For instance, the change in price for one day is usually less than the change in price for the week. The difference between the high price and the low price, over any given time period, is referred to as the range value.
Determine the time period to calculate the range value over. You can look at the range value over one day or three years. Let's say you want to determine the range value over one year, or 52 weeks.
Determine the highest price of the stock over the given time period. This is referred to as the price high. Most investment research sites will automatically calculate the 52-week high for the stock (see Resources). If they do not, simply chart the price of the stock over the past year to determine the highest value of the stock price over the past year. Let's say the highest price paid for XYZ stock is $50 over the past year.
Determine the lowest price of the stock over the given time period. This is referred to as the price low. You can determine the low in the same way you determine the high. Let's say the lower price paid for XYZ stock over the past year is $25.
Calculate the range value. Subtract the highest price from the lowest price over the given time period. The calculation is: $50 - $25 = $25.