How to Decide How Much Hard Drive Space You Need

Decide how much hard drive space you need.

Hard drives have certainly come a long way: the world's first 1GB drive (an IBM 3380 released in 1980) weighed over 500 lbs. and cost about $40,000. At the time of publication, computer hard drives vary in size from an 80GB hard drive to breakthrough systems that hold up to 2 terabytes of storage. With such a drastic range of availability in hard drive sizes, it can be difficult to determine how much hard drive space is needed to meet your individual computing needs. Follow these tips to determine just how much hard drive space you need for your next computer.

Step 1

Know your terminology. When it comes to computers, can you tell a bit from a byte? Mastering some simple computer terminology can help you approach your hard drive purchase with confidence.

Bit: A bit is the smallest unit of information in a computer. A bit is represented by either a zero or one. This sequence of zeros and ones is called binary code.

Byte: A sequence of eight bits makes up one byte. Each byte can represent a character such as a number or a letter of the alphabet. For example, it takes one byte to represent the letter "A" which is made up of the eight bits 01000001.

Kilobyte: 1,000 bytes (8,000 bits)

Megabyte: 1,000 kilobytes (100,000 bytes; 800,000 bits)

Gigabyte: 1,000 megabytes (100,000 kilobytes; 100,000,000 bytes; 800,000,000 bits)

Terabyte: 1,000 gigabytes (100,000 megabytes; 100,000,000 kilobytes; 100,000,000,000 bytes; 800,000,000,000 bits)

Step 2

Know how much space you need. If you already have a computer, start by checking to see how much hard drive space you're currently using. To do this, navigate to the "Start" menu and select "Computer" and right-click on your hard drive. A graph will appear showing you how much hard drive space you are using. Identify your greatest memory users. Here's a few rules of thumb to help you:

A large, high resolution photo can easily take up 1 to 2MB, while a smaller photo can be compressed to under 200KB.

A two-hour movie will take up about 2GB.

An average-length song takes up about 1MB.

An advanced video game like Oblivion can take up to 5GB of memory.

Step 3

Decide what your future hard drive needs will be. Now that you know how much hard drive space you are presently using, decide if this is about right for your next computer, or if you'd like to increase your current computer's hard drive amount. If your new computer will have new features like a TV tuner that records your favorite shows, keep this in mind as you calculate your future hard drive needs. Also, remember that common computer applications continue to require more hard drive space as systems emerge with ever larger hard drives. So, even if you don't plan to greatly change your computer storage habits, you should consider an upgrade in hard drive size if your current system is more than 75 percent full.


Numbers used for memory are rounded down. To be exact, a kilobyte is 1,024 bytes, with each subsequent byte interval being a multiple of 1,024.