You just unboxed a brand-new 1TB external drive. It looks sleek. It smells like new plastic and high expectations. But the second you plug it into your Windows PC, you see it: 931 GB available.
Wait, what? Where did the rest go? Did the manufacturer rip you off? Did the "formatting" really eat nearly 70 gigs of space?
Honestly, it’s one of the most annoying quirks of modern computing. If you're asking how many gigs in a tb, the answer isn't a simple number. It's actually two different numbers fighting for your attention.
In the world of marketing and stickers on boxes, 1 TB equals 1,000 GB.
In the world of your computer’s brain (binary), 1 TB equals 1,024 GB.
This 24-gigabyte difference sounds small, but as you scale up to terabytes, that "math gap" turns into a giant hole in your storage. Let's break down why this happens and what you’re actually getting for your money.
The Great Decimal vs. Binary War
The confusion starts with how we count. Most humans use the decimal system. We have ten fingers, so we like powers of ten. Kilo means 1,000. Mega means 1,000,000. Easy, right?
Hard drive manufacturers love this. They follow the International System of Units (SI). To them, a Terabyte is exactly $10^{12}$ bytes. That is a clean 1,000,000,000,000 bytes. When they put "1 TB" on the box, they are legally and technically correct according to the decimal system.
But computers are weird.
They don't have fingers; they have transistors that are either "on" or "off." That’s binary (Base-2). Because $2^{10}$ is 1,024, that’s the number computers use as their "kilo."
- 1 KB (Binary) = 1,024 Bytes
- 1 MB (Binary) = 1,024 KB
- 1 GB (Binary) = 1,024 MB
- 1 TB (Binary) = 1,024 GB
When Windows looks at that "1,000,000,000,000 byte" drive, it starts dividing by 1,024 instead of 1,000.
$1,000,000,000,000 / 1,024 / 1,024 / 1,024 = 931.32$.
That is why your 1TB drive shows up as 931 GB. You haven't lost any data; you're just looking at a different ruler.
Wait, Why Does My Mac Say Something Different?
Here’s a fun twist. If you’re a Mac user, you might have noticed your storage actually matches the box. Since macOS Snow Leopard (way back in 2009), Apple switched their operating system to use decimal math.
If you buy a 1TB drive and plug it into a Mac, it says 1TB. Apple decided it was easier to change the software than to explain binary math to millions of people. Linux (depending on the distro) and Android usually do this too. Windows is the main holdout that still insists on showing you the binary "GiB" (Gibibytes) while labeling them as "GB."
How Much Can You Actually Fit in 1TB?
Numbers on a screen are fine, but what does 1TB actually look like in your daily life? If you're a gamer, a photographer, or someone who just hoards memes, the "how many gigs in a tb" question is really about capacity.
Let’s look at some real-world 2026 standards:
1. Modern AAA Games
Games aren't getting smaller. A title like Call of Duty or the latest Grand Theft Auto can easily eat 150GB to 200GB. On a 1TB drive (which is actually 931GB usable on Windows), you’re looking at maybe 5 or 6 "big" games before you’re out of room.
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2. 4K and 8K Video
If you're shooting 4K video at 60fps on your phone, you're burning through about 400MB every minute.
In a 1TB space, you can hold roughly 40 hours of high-quality 4K footage. If you step up to 8K, cut that number by four.
3. High-Res Photos
For the casual smartphone user, 1TB is massive. You could store roughly 250,000 photos (assuming 4MB per photo). You’d have to try pretty hard to fill that up with just selfies.
4. Professional RAW Files
If you’re a pro photographer using a Nikon or Sony mirrorless camera, your RAW files might be 50MB to 100MB each. Now, that 1TB drive only holds about 10,000 to 20,000 images. For a wedding photographer, that might be just two or three gigs (pun intended).
The "Hidden" Storage Eaters
Even after you solve the decimal vs. binary mystery, you still won't have the full 931 GB free.
The File System
When you format a drive (NTFS for Windows, APFS for Mac), the drive needs to create a "map" of where everything is. This takes up a bit of space. It's like a library needing to reserve a few shelves just for the card catalog.
Over-provisioning
On modern SSDs, the drive controller often hides a portion of the storage to use for "wear leveling." It swaps out dead cells for fresh ones in the background to keep the drive from dying. You can't see this space, and you can't use it, but it's there, making the drive last longer.
Partitioning
Laptop makers often put a "Recovery Partition" on your internal drive. This is a secret slice of your 1TB that holds a backup of Windows. It can take up 10GB to 20GB, further shrinking what you see in "My Computer."
Why This Matters for Your Wallet
When you're shopping for cloud storage—like Google Drive, iCloud, or Dropbox—they almost always use the decimal (1,000 GB) definition.
If you pay for 1TB of cloud storage, you are getting 1,000 Gigabytes.
If you try to back up a physical 1TB hard drive that is completely full (meaning it has 1,024 binary Gigabytes of data) to a 1TB cloud account, it will fail. You’ll be about 24GB short.
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This is the "gotcha" moment for a lot of people. Always leave yourself a 10% buffer when planning your backups.
Actionable Tips for Managing Your Terabytes
- Check the Label: If you are on Windows, always multiply the advertised TB by 0.93 to get the "real" usable space you'll see in the OS.
- Avoid the 100% Full Trap: SSDs slow down significantly once they pass 80-90% capacity. If your 1TB drive has less than 100GB free, it's time to start deleting or offloading.
- Mix and Match: Don't put everything on one drive. Use a 1TB SSD for your active projects and games, and a cheaper, larger 4TB or 8TB HDD for long-term "cold" storage of photos and videos.
- Use WinStatDir or DaisyDisk: These tools give you a visual map of your drive. Sometimes you'll find that 50GB of your "missing" space is just a temp folder or an old game update you forgot to delete.
Understanding how many gigs in a tb is mostly about knowing who is doing the talking. If it's a salesperson, it's 1,000. If it's your computer, it's 1,024. Just remember that "missing" 7% is the tax we pay for the industry never agreeing on a single way to count.