How to Add More Storage to Your Computer

The three ways to add storage to your computer

You can add storage to a Windows or Mac computer in three ways: install a second internal drive, replace your existing drive with a larger one, or connect an external drive. Internal drives are fastest and take up no desk space. External drives are easiest to install yourself and can move between computers. Replacing your main drive is the most involved but gives you the most usable space if your current drive is nearly full.

Which route makes sense depends on whether your computer has room for a second drive, how much storage you need, and whether you want the speed benefit of an internal drive. A laptop typically has room for only one drive, so you would either replace it or use external storage. A desktop usually has space for a second drive, which is the easiest upgrade.

Key Takeaways

A second internal drive is fastest and invisible but requires opening your computer and works only if you have a free slot.
An external drive plugs into a USB port, works with any computer, and costs less per gigabyte than internal drives.
Replacing your main drive requires backing up everything first and reinstalling Windows or macOS, but gives you the most space if your current drive is full.
Solid-state drives (SSDs) are now standard and much faster than older spinning hard drives (HDDs), so any new drive you buy will be an SSD.
Before you buy, check whether your computer has a free drive slot and what type of connection it uses—SATA, NVMe, or USB.

Adding a second internal drive to a desktop

If you have a desktop computer with an empty drive bay, adding a second internal drive is the fastest and cheapest way to gain storage. You will need to open the computer case, which sounds intimidating but usually means removing two or four screws on the back panel. Inside, you will see drive bays—rectangular slots where drives sit. If one is empty, you can install a new drive there.

Before you buy a drive, check what type of connection your computer uses. Most modern desktops use NVMe (a small stick-shaped drive that plugs into a slot on the motherboard) or SATA (a flat drive that connects with a cable). Your computer's manual or the manufacturer's website will tell you which type you have and whether a free slot exists. If you are unsure, a computer repair shop can check for you in five minutes.

Once you have the right drive, installation takes about ten minutes. You will slide the drive into the bay, find it with screws, and plug in the power cable if it is a SATA drive. NVMe drives need no cables—they plug directly into the motherboard. After you restart the computer, Windows will recognize the new drive automatically. You will see it in File Explorer as a new storage location.

Using an external drive for storage

An external drive is the simplest option if you do not want to open your computer or if your computer has no free internal slots. You plug it into a USB port, and it appears on your desktop or in File Explorer when ready. External drives cost less per gigabyte than internal drives and work with any computer—you can move the same drive between a laptop, desktop, or Mac.

External drives come in two types: portable (about the size of a deck of cards, powered by the USB connection itself) and desktop (larger, with their own power cord). Portable drives are lighter and good for backing up files or carrying data between locations. Desktop drives are faster and better for storing large video or photo libraries that you access regularly.

The main trade-off is speed. An external drive connected by USB 3.0 is slower than an internal SATA drive and much slower than an internal NVMe drive. If you are only storing files you rarely access—old projects, archived photos, backups—the speed difference does not matter. If you work with large video files or run programs from the external drive, the slowness becomes noticeable.

Replacing your main drive with a larger one

If your current drive is nearly full and you want to keep all your programs and files, you can replace it with a larger drive. This is more involved than adding a second drive because you must back up everything first, then reinstall Windows or macOS on the new drive.

Start by backing up your entire computer. Windows has a built-in backup tool called File History; macOS has Time Machine. Both create a complete copy of your system and files. This backup takes several hours depending on how much data you have, so plan for an evening or overnight. Do not skip this step—if something goes wrong during the replacement, your backup is your only way to recover your files.

Once you have a backup, shut down the computer, remove the old drive, and install the new one in its place. Then restart the computer with a Windows or macOS installation disc or USB drive (you can create one on another computer using Microsoft's or Apple's official tools). The operating system will install fresh on the new drive. After installation, you restore your files from the backup. The whole process takes four to six hours.

Understanding drive size and speed specifications

Storage drives are measured in gigabytes (GB) and terabytes (TB). One terabyte equals 1,000 gigabytes. A typical laptop comes with 256 GB or 512 GB. If you store photos, videos, or large programs, you will fill that quickly. Most people buying a new internal drive choose 1 TB or 2 TB.

All new drives are solid-state drives (SSDs), which have no moving parts and are much faster than the older spinning hard drives (HDDs) that came in computers five or more years ago. If you are replacing an old drive, you will notice a significant speed improvement just from switching to an SSD. You do not need to choose between different speed levels—any modern SSD is fast enough for everyday use.

When shopping, you will see brands like Samsung, Crucial, Western Digital, and Kingston. All are reliable. The main difference is warranty length and price per gigabyte. A 1 TB drive typically costs between $50 and $100 depending on the brand and type. External drives cost slightly less per gigabyte because they have fewer components.

When to call a professional for help

If your computer is still under warranty, opening it yourself may void the warranty. Check your warranty documents or the manufacturer's website before you start. If you are uncomfortable opening the computer or unsure whether you have a free drive slot, a local computer repair shop can install a drive for you in an hour or two, usually for $50 to $100 in labor.

If you are replacing your main drive, a professional can handle the backup, installation, and restoration, which saves you time and reduces the risk of losing data. This is worth the cost if you have thousands of files or programs you depend on.

Frequently Asked Questions

How much storage do I actually need?

It depends on what you store. If you use your computer mainly for email, web browsing, and documents, 256 GB is usually enough. If you store photos, videos, or large programs, aim for 1 TB. If you work with video editing or have a large music library, 2 TB or more is safer. You can always add an external drive later if you run out of space.

Can I use an external drive as my main drive?

Yes, but it will be slower than an internal drive. Some people boot their computer from an external SSD and it works fine for everyday tasks. If you do this, use a desktop external drive with its own power cord rather than a portable one—it will be more reliable and faster.

What is the difference between USB 3.0 and USB-C?

USB-C is a newer connector shape that is faster than older USB 3.0 connectors. If your computer has USB-C ports, buy an external drive with USB-C for the best speed. If you only have USB 3.0 ports, a USB 3.0 drive will work fine. Most modern external drives come with USB-C.

Do I need to format a new drive before using it?

Internal drives usually come pre-formatted and work when ready after installation. External drives also come pre-formatted, but if you are moving a drive between a Windows computer and a Mac, you may need to reformat it. Windows and Mac use different file systems. Your computer will prompt you to format if needed when you first connect the drive.

Is it safe to leave an external drive plugged in all the time?

Yes. External drives are designed to run continuously. If you use the drive for backups, leaving it plugged in ensures your backup stays current. If you use it for storage you access regularly, leaving it plugged in is fine. Unplug it only if you are moving the computer or will not use it for weeks.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.