Last updated: September 16, 2026
Quick answer: Multiply gigabytes by 1,024 to get megabytes (binary). 1 GB = 1,024 MB in computing. In storage marketing (SI), 1 GB = 1,000 MB. So a "128 GB" phone holds about 131,072 MB of actual binary storage.
Gigabyte to Megabyte
Instantly convert gigabyte to megabyte with fast, accurate, real-time results.
Gigabytes and megabytes show up on phone specs, file sizes, internet data plans, and download speeds — but the number on the box doesn't always match what your device reports. That's because manufacturers and operating systems use different definitions of "GB." This page explains both, and the MB to GB converter handles the reverse.
Formula: GB to MB
There are two definitions in common use:
Decimal (SI/marketing): MB = GB × 1,000
Operating systems (Windows, macOS, Linux, Android, iOS) use the binary definition — 1 GB = 2³⁰ bytes = 1,073,741,824 bytes = 1,024 MB. Storage manufacturers use the decimal definition — 1 GB = 10⁹ bytes = 1,000,000,000 bytes = 1,000 MB. This is why a "256 GB" SSD shows up as 238 GB in Windows.
Binary vs. Decimal: Why Your Phone Shows Less Storage
| Labeled capacity | Decimal bytes | What OS shows (binary GB) | Difference |
|---|---|---|---|
| 64 GB phone | 64,000,000,000 bytes | ≈ 59.6 GB | −7% |
| 128 GB phone | 128,000,000,000 bytes | ≈ 119.2 GB | −7% |
| 256 GB phone | 256,000,000,000 bytes | ≈ 238.4 GB | −7% |
| 512 GB drive | 512,000,000,000 bytes | ≈ 476.8 GB | −7% |
| 1 TB drive | 1,000,000,000,000 bytes | ≈ 931.3 GB | −7% |
Phone Storage Guide
How much can you actually store? Typical file sizes to put phone storage in perspective:
| Content type | Typical size | On a 128 GB phone (~119 GB usable) |
|---|---|---|
| Photo (12 MP HEIF) | 3–5 MB | ~25,000–40,000 photos |
| Photo (12 MP JPEG) | 4–7 MB | ~17,000–30,000 photos |
| 4K video (1 min) | 350–500 MB | ~240–340 minutes |
| 1080p video (1 min) | 130–200 MB | ~600–900 minutes |
| Song (MP3, 320 kbps) | 8–10 MB | ~12,000–15,000 songs |
| App (typical) | 50–300 MB | ~400–2,400 apps |
| Game (large) | 1–5 GB | ~24–119 games |
| Movie (HD download) | 3–5 GB | ~24–40 movies |
Common File Sizes in MB and GB
| File / data type | Size in MB | Size in GB |
|---|---|---|
| Text document (1,000 pages) | ~5 MB | 0.005 GB |
| PDF (scanned, 100 pages) | ~50 MB | 0.05 GB |
| High-res image (RAW) | 20–50 MB | 0.02–0.05 GB |
| Album (FLAC lossless) | 300–400 MB | 0.3–0.4 GB |
| Software installer | 200–800 MB | 0.2–0.8 GB |
| Blu-ray movie (rip) | 25,000–50,000 MB | 25–50 GB |
| Windows 11 ISO | ~5,200 MB | ~5.1 GB |
| Video game (AAA) | 30,000–100,000 MB | 30–100 GB |
Full GB to MB Table
| GB | MB (binary) | MB (decimal) |
|---|---|---|
| 0.5 GB | 512 MB | 500 MB |
| 1 GB | 1,024 MB | 1,000 MB |
| 2 GB | 2,048 MB | 2,000 MB |
| 4 GB | 4,096 MB | 4,000 MB |
| 8 GB | 8,192 MB | 8,000 MB |
| 16 GB | 16,384 MB | 16,000 MB |
| 32 GB | 32,768 MB | 32,000 MB |
| 64 GB | 65,536 MB | 64,000 MB |
| 128 GB | 131,072 MB | 128,000 MB |
| 256 GB | 262,144 MB | 256,000 MB |
| 512 GB | 524,288 MB | 512,000 MB |
| 1,000 GB | 1,024,000 MB | 1,000,000 MB |
FAQs About GB to MB
Is 1 GB equal to 1,000 MB or 1,024 MB?
Both are in use. In computing (operating systems, RAM specs), 1 GB = 1,024 MB (binary, using powers of 2). In storage marketing and the SI system, 1 GB = 1,000 MB (decimal). The IEC standard uses "GiB" (gibibyte) for the 1,024 definition, but most operating systems still display GiB as "GB."
Why does my 256 GB phone only show 238 GB?
The manufacturer labels the drive using the decimal definition (256 × 10⁹ bytes). Your phone's OS converts that to binary gigabytes (÷ 1,024³), giving 238.4 GB. No storage was hidden or removed — it's just two different ways to count the same bytes.
How many MB is 1.5 GB?
1.5 GB = 1,536 MB (binary) or 1,500 MB (decimal). In most computing contexts, 1,536 MB is the right answer.
What is a gigabyte in bytes?
Binary: 1 GB = 2³⁰ = 1,073,741,824 bytes. Decimal (SI): 1 GB = 10⁹ = 1,000,000,000 bytes.
How many GB is 500 MB?
500 MB ÷ 1,024 = 0.488 GB (binary). In decimal, 500 MB = 0.5 GB exactly. For the reverse conversion, see the MB to GB converter.
Sources
References & further reading
- International Electrotechnical Commission (IEC) — IEC 80000-13:2008 — defines gibibyte (GiB = 2³⁰ bytes) and gigabyte (GB = 10⁹ bytes)
- NIST — Prefixes for binary multiples (recommends GiB for 2³⁰; notes industry use of GB for both)
- IEEE Std 1541-2002 — Prefixes for Binary Multiples
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