Two conversions most people run into constantly, for very different reasons: converting money between currencies, and figuring out why a storage device never quite matches the number printed on the box. Both come down to a specific, learnable rule.
Why storage devices always show "less" than advertised
This isn't a manufacturing defect or a scam — it's two different, both technically valid, definitions of "gigabyte" colliding.
| System | Definition of 1 GB | Used by |
|---|---|---|
| Decimal (SI) | 1,000,000,000 bytes | Storage manufacturers (on the box) |
| Binary | 1,073,741,824 bytes | Most operating systems (what you see on screen) |
Worked example: a drive advertised as 1TB, using the manufacturer's decimal definition:
| Calculation | Result |
|---|---|
| 1,000,000,000,000 bytes ÷ 1,073,741,824 (binary GB) | ≈931.32 GB |
Nothing was lost or hidden — the drive genuinely has close to 1 trillion bytes. It's just that when your operating system reports that same byte count using the binary definition of "gigabyte," the number it displays is smaller. This is also why the technically correct term for the binary unit is gibibyte (GiB), not gigabyte — but "GB" gets used loosely for both in everyday language, which is the actual source of the confusion.
Currency conversion: a moving target
The calculation itself is simple multiplication — the complexity is entirely in the exchange rate, which represents how much of one currency is needed to buy one unit of another. Unlike a fixed unit conversion (like meters to feet, which never changes), currency exchange rates shift continuously based on global market conditions — interest rates, economic data releases, trade activity, and investor sentiment all move rates, sometimes meaningfully within a single day.
This means a currency conversion is only as accurate as the exchange rate used, and that rate is only valid at the moment it was checked — unlike unit conversions, there's no single "correct" exchange rate that stays fixed over time.
The common thread
Both of these conversions look like they should be simple multiplication (and mechanically, they are) — but getting the right input matters as much as the arithmetic. For storage, that means knowing whether you're working with decimal or binary units. For currency, it means using a current, accurate exchange rate rather than an outdated one.
Try the calculators
The digital storage converter converts between bytes, KB, MB, GB, and TB using binary (1024-based) units, matching how most operating systems report storage. The currency converter applies a given exchange rate to convert between amounts — enter the current rate for an accurate result.
Frequently asked questions
Why does my 1TB hard drive show less than 1TB of usable space?
Manufacturers advertise storage using decimal units (1TB = 1,000,000,000,000 bytes), while operating systems typically display storage using binary units (1GB = 1,073,741,824 bytes). Converting the same 1TB (decimal) into binary GB gives roughly 931GB, which is why the number shown is always lower than the number on the box.
How does currency conversion actually work?
You multiply the amount by the current exchange rate between the two currencies. Exchange rates fluctuate constantly based on global markets, so a conversion is only accurate at the specific moment the rate was checked.
Why do exchange rates change so often?
Currency values are set by global foreign exchange markets and shift continuously based on factors like interest rates, economic data, trade flows, and investor sentiment — they can change meaningfully within a single day.
What's the difference between a kilobyte and a kibibyte?
A kilobyte (kB) technically means 1,000 bytes in the decimal (SI) system, while a kibibyte (KiB) means 1,024 bytes in the binary system. In everyday use, "KB", "MB", and "GB" are often used loosely to mean either, which is the root of most storage-size confusion.