Convert KB, MB, GB, KiB, MiB, GiB, Mbit — SI vs IEC made obvious.
Updated
| Unit | Value | Copy |
|---|---|---|
Bit bit | 8,000,000,000 | |
Byte B | 1,000,000,000 | |
Kilobyte (SI, 10³) kB | 1,000,000 | |
Kibibyte (IEC, 2¹⁰) KiB | 976,562.5 | |
Megabyte (SI, 10⁶) MB | 1,000 | |
Mebibyte (IEC, 2²⁰) MiB | 953.67431641 | |
Gigabyte (SI, 10⁹) GB | 1 | |
Gibibyte (IEC, 2³⁰) GiB | 0.93132257 | |
Terabyte (SI, 10¹²) TB | 0.001 | |
Tebibyte (IEC, 2⁴⁰) TiB | 0.00090949 | |
Petabyte (SI, 10¹⁵) PB | 1.000000e-6 | |
Pebibyte (IEC, 2⁵⁰) PiB | 8.881784e-7 | |
Megabit (bandwidth) Mbit | 8,000 | |
Gigabit (bandwidth) Gbit | 8 |
Quick start
Type a size in any unit, see it expressed in every other unit — SI vs IEC clearly distinguished.
Enter the size and pick its unit. Switching units converts the displayed value so the meaning is preserved.
Fourteen units — bits, bytes, SI decimal, IEC binary and network bandwidth — update live. The source unit is highlighted.
Click Copy on any row to grab the converted value. Everything runs locally — no upload.
In-depth guide
Convert between fourteen data-size units: bits, bytes, SI decimal (kB, MB, GB, TB, PB), IEC binary (KiB, MiB, GiB, TiB, PiB) and network bandwidth (Mbit, Gbit). The two prefix systems diverge with size — important when sizing storage or network capacity.
| Unit | Symbol | In bytes |
|---|---|---|
| Bit | bit | 0.125 |
| Byte | B | 1 |
| Kilobyte (SI) | kB | 1 000 |
| Kibibyte (IEC) | KiB | 1 024 |
| Megabyte (SI) | MB | 1 000 000 |
| Mebibyte (IEC) | MiB | 1 048 576 |
| Gigabyte (SI) | GB | 1 000 000 000 |
| Gibibyte (IEC) | GiB | 1 073 741 824 |
| Terabyte (SI) | TB | 10¹² |
| Tebibyte (IEC) | TiB | 2⁴⁰ |
| Petabyte (SI) | PB | 10¹⁵ |
| Pebibyte (IEC) | PiB | 2⁵⁰ |
| Megabit (bandwidth) | Mbit | 125 000 |
| Gigabit (bandwidth) | Gbit | 125 000 000 |
The original "kilo" / "mega" prefixes mean exactly 10³ and 10⁶. Computer scientists co-opted them in the 1960s to mean 2¹⁰ and 2²⁰ because those values were close enough — and the ambiguity stuck. IEC 60027-2 (1999) introduced the binary prefixes (kibi, mebi, gibi, ...) to remove the conflict.
| Size | SI (decimal) | IEC (binary) | Difference |
|---|---|---|---|
| k vs Ki | 1 000 | 1 024 | +2.4% |
| M vs Mi | 10⁶ | 2²⁰ | +4.9% |
| G vs Gi | 10⁹ | 2³⁰ | +7.4% |
| T vs Ti | 10¹² | 2⁴⁰ | +10.0% |
| P vs Pi | 10¹⁵ | 2⁵⁰ | +12.6% |
The discrepancy is what makes a "1 TB" drive show as "~931 GB" in Windows — it's actually 1 SI TB ÷ 1 IEC GiB = 10¹² / 2³⁰ ≈ 931.32.
Network throughput is measured in bits per second by convention. A 100 Mbit/s connection moves 12.5 MB/s of bytes (100 ÷ 8). When estimating download times for files quoted in MB/GB, convert to Mbit first and divide by your link speed:
1 GB file ÷ 100 Mbit/s = 8 000 Mbit ÷ 100 Mbit/s = 80 s
1 GB file ÷ 1 Gbit/s = 8 000 Mbit ÷ 1 000 Mbit/s = 8 sWhen to reach for it. Use it to convert between bits, bytes, KB/MB/GB and their binary KiB/MiB/GiB cousins for storage and bandwidth math.
When something else is better. Exact billing or provisioning should follow your vendor’s stated unit definition.
The pitfall to watch. Drives are sold in decimal (1 GB = 1000³ bytes) but operating systems often report binary (1 GiB = 1024³) — that’s why a “1 TB” drive looks smaller in your OS.
Everything runs on your device. The values you enter are processed locally in this browser tab — EpitomeTool does not send your input to a server, store it, or log it. That means you can use the tool offline once the page has loaded, and refreshing the tab wipes the slate.
GB is the SI (decimal) gigabyte: 10⁹ bytes = 1 000 000 000. GiB is the IEC (binary) gibibyte: 2³⁰ bytes = 1 073 741 824. The gap grows with size — a 1 TiB drive is about 9.95% bigger than a 1 TB drive. Storage manufacturers advertise in SI (GB/TB); OS reporting is mixed (macOS / Linux use SI; Windows displays binary values but labels them GB).
Windows divides bytes by 1 073 741 824 (2³⁰, a gibibyte) but labels the result 'GB'. 500 × 10⁹ ÷ 2³⁰ ≈ 465.66 — that's why. The drive really is 500 SI gigabytes; it's just measured against the IEC ruler with an SI label.
No. 1 MB/s = 8 Mbit/s. ISP bandwidth is quoted in Mbit/s (smaller-sounding number, larger-looking marketing); file-transfer speeds are usually shown in MB/s. A 100 Mbit/s connection peaks at 12.5 MB/s.
The international standard (1999, revised 2019) that formalised KiB / MiB / GiB / TiB / PiB to disambiguate from SI prefixes. "The IEC adopted the prefixes for binary multiples in 1998 to alleviate the confusion between decimal and binary metric prefixes," per the standard's introduction. Adoption is now near-universal in technical specs and increasingly common in consumer software.
Decimal (kB, MB, GB) for: storage media size, network transfer, anything user-facing where SI conventions apply. Binary (KiB, MiB, GiB) for: RAM (always sold in powers of 2), cache lines, page sizes, anything where the underlying hardware works in binary. When in doubt and precision matters, write the explicit count (e.g. "2 ^ 30 bytes") to remove ambiguity.
Yes. Everything runs in your browser. No request leaves the page during conversion.
Keep exploring
Hand-picked utilities that pair well with the one you're on — all free, client-side, and zero-signup.
Shrink PDF file size without uploading to a server.
Body Mass Index with metric / imperial inputs and WHO category bands.
Combine multiple PDFs into one in your browser.
Split a PDF by pages or page ranges, download as zip.