Data Storage Converter

How to Convert a Data Storage Value

Features

Where the Other 69 Gigabytes Went

Plug in a drive labelled "1 TB" and Windows reports 931 GB. Nothing is missing, no space has been swallowed by hidden partitions — two different counting systems are measuring the exact same trillion bytes and landing on different-looking numbers. The manufacturer counts in decimal, exactly the way the label promises: 1,000,000,000,000 bytes, full stop. Windows divides that figure using binary math instead, where the nearest "kilo" is 1,024 rather than 1,000 — run a trillion bytes through that chain of divisions and you land on roughly 931.32, which Windows then displays with the misleading label "GB" when it actually means GiB. macOS switched to genuinely decimal reporting back in 2009 with Snow Leopard, which is why the identical drive shows a number much closer to 1 TB on a Mac. The gap between the two systems isn't a rounding error, either — it widens as the numbers get bigger, from about 2.4% at the megabyte scale to nearly 10% by the time you reach terabytes. Linux tools split the difference depending on which flag you pass: df -h reports binary GiB by default, while df -H — capital H — switches to the same decimal counting the drive manufacturer used, which is a detail worth knowing before comparing disk-usage output between two machines that were invoked slightly differently.

A Bit Is Not a Byte, and Your ISP Is Counting on That

Storage is measured in bytes. Network speed is almost always advertised in bits per second, and the two units look similar enough on a page that the distinction quietly disappears for most people reading it. A "100 Mbps" broadband plan is 100 megabits per second — divide by 8 to get actual megabytes per second, and the real download speed is 12.5 MB/s, not 100. A 250 MB file that "should" take a couple of seconds on a 100 Mbps line actually takes closer to 20, which is exactly the kind of gap that makes an advertised internet speed feel slower than the number on the bill implies. It isn't deceptive marketing so much as an inherited convention — network engineering has measured throughput in bits since long before consumer broadband existed, and nobody ever switched.

A Photo Backup, a Game Install, and a Data Centre

Someone backing up a phone full of photos to a cloud plan sold in decimal GB watches the OS report binary GiB usage instead, and ends up slightly confused about how much of the plan is actually left. A gamer checking whether a 92 GiB install will fit an 80 GB drive as reported by the manufacturer needs to know instantly whether that's actually going to fit — converted to the same system, 92 GiB is about 98.8 GB, which doesn't fit at all, a mismatch worth catching before the download starts rather than partway through a download that was never going to complete. A systems administrator sizing a new storage array works entirely in petabytes and needs to know exactly how many tebibytes that translates to for a specific vendor's per-drive specifications. And someone burning files to a DVD wonders why a folder that Windows reports as "4.4 GB" barely fits on a disc marketed as 4.7 GB — the disc capacity is decimal, the folder size shown is binary, and the two numbers were never going to match without a conversion in between. A network engineer sizing a backup window has the opposite problem in reverse — a stated transfer speed in Mbps needs to be divided by 8 before it means anything useful next to a storage figure quoted in bytes, and skipping that step is exactly how a "quick overnight backup" estimate ends up wrong by a factor of eight. Programmers working closer to the metal run into a related but separate representation question — a byte value is often written in hexadecimal rather than decimal once code gets involved, which is a job for the Number Base Converter rather than this tool; the two problems look adjacent but solve genuinely different questions.

Built to Answer "How Long Will This Actually Take?"

Most storage converters stop at a converted number. This one adds the question that usually follows right after: how long will moving this file actually take? The File Transfer Time Calculator below the main converter accepts a file size in any supported unit and a transfer speed in Mbps, with preset buttons for USB 2.0, USB 3.0, gigabit Ethernet, typical home Wi-Fi, and common broadband tiers — all calibrated to realistic throughput rather than theoretical maximum bandwidth, since a USB 3.0 port rated at 5 Gbps rarely sustains anywhere near that in an actual file copy. Next to the main result, a Common File Sizes panel anchors an abstract number to something recognisable — from a text message up to a Blu-ray disc's full capacity — highlighting whichever reference sits closest to your current figure. And three filter chips above the full unit table — Bits & Bytes, Decimal (SI), Binary (IEC) — keep a quick drive-capacity check from sharing space with units it has no use for. Precision follows the same pattern as the rest of this converter family: Auto keeps everyday figures short and readable, while a fixed 2, 4, 6, or 8 decimal-place setting is there for the moment a capacity-planning spreadsheet needs one consistent format all the way down rather than whatever looks tidiest.

What This Converter Won't Predict

The Transfer Time Calculator estimates based on the speed you enter — it cannot account for a slow source drive, a congested network, background traffic, or protocol overhead, all of which routinely pull real-world transfer speed well below a device's rated maximum. It also doesn't model filesystem overhead or compression: the "size" Windows reports for a folder can differ slightly from the sum of the files inside it once cluster allocation is accounted for, and a compressed archive's size bears no fixed relationship to the uncompressed data it contains. Nothing typed here is sent anywhere: the arithmetic runs as plain JavaScript inside the browser tab, with no server call and nothing logged, which matters for confidential infrastructure sizing or backup planning as much as for checking a phone's storage tier. For anything with contractual or capacity-planning weight behind it — a data centre procurement, an SLA commitment — treat the output as a fast, accurate estimate and confirm it against real-world benchmarks, and the tool keeps working identically with no internet connection at all once the page has loaded — a small irony for a tool that spends so much of its time talking about network speed.