Converters Kilobytes to megabytes
Convert kilobytes to megabytes in both the decimal and binary conventions, with a reference chart of common file sizes.
1 kB = 0.001 MB
megabytes = kilobytes × 0.001
kilobytes to megabytes
| kB | MB |
|---|---|
| 1 | 0.001 |
| 2 | 0.002 |
| 3 | 0.003 |
| 4 | 0.004 |
| 5 | 0.005 |
| 10 | 0.01 |
| 15 | 0.015 |
| 20 | 0.02 |
| 25 | 0.025 |
| 50 | 0.05 |
| 75 | 0.075 |
| 100 | 0.1 |
| 500 | 0.5 |
| 1,000 | 1 |
One kilobyte is exactly 0.001 megabytes.
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Cite this page
Reembun. (2026, July 28). Kilobytes to megabytes. https://reembun.com/convert/data/kb-to-mb
How to use it
Type the kilobytes
Megabytes appear as you type.
Know which convention you need
This uses the decimal units your storage and your network are sold in, where a megabyte is 1000 kilobytes. The binary kibibyte and mebibyte are in the unit list for what an operating system reports.
Copy it or read the table
Swap units converts megabytes back into kilobytes, and the table covers the sizes that come up in upload limits.
The two conventions
Decimal (SI) 1 MB = 1000 kB
Binary (IEC) 1 MiB = 1024 KiBBoth are legitimate. The binary convention exists because computers address memory in powers of two; the decimal one because every other SI prefix means a power of ten. Neither side conceded, so both survive with confusingly similar names.
| Unit | Decimal bytes | Binary bytes | Gap |
|---|---|---|---|
| kB / KiB | 1,000 | 1,024 | 2.4% |
| MB / MiB | 1,000,000 | 1,048,576 | 4.9% |
| GB / GiB | 10⁹ | 1,073,741,824 | 7.4% |
Quick reference
| KB | MB (decimal) |
|---|---|
| 100 | 0.1 |
| 250 | 0.25 |
| 500 | 0.5 |
| 1,000 | 1 |
| 1,024 | 1.024 |
| 5,000 | 5 |
| 10,000 | 10 |
Typical file sizes
| File | Typical size |
|---|---|
| Favicon | 1-5 KB |
| Web font, one weight subset | 15-30 KB |
| Optimised web image | 50-200 KB |
| Photo from a phone | 2-5 MB |
| Photo from a DSLR, RAW | 20-50 MB |
| Minute of MP3 at 192 kbps | ~1.4 MB |
| Minute of 1080p video | ~60 MB |
| Minute of 4K video | ~350 MB |
Web performance targets
For a page that needs to load on mobile data:
| Asset | Budget |
|---|---|
| Total page weight | Under 1 MB |
| Hero image | Under 200 KB |
| Content images | Under 100 KB each |
| CSS | Under 50 KB |
| JavaScript | Under 150 KB |
These are guidelines rather than rules, but they are achievable. This site’s own tool pages come in around 25 KB compressed.
Email attachment limits
Attachments are Base64-encoded for transport, inflating them by roughly 33%.
| Provider | Stated limit | Real file limit |
|---|---|---|
| Gmail | 25 MB | ~18 MB |
| Outlook | 20 MB | ~15 MB |
| Typical corporate | 10 MB | ~7.5 MB |
This is why a 22 MB file is rejected by a service advertising a 25 MB limit. Compressing to a ZIP rarely helps for photos or video, which are already compressed. Sharing a link is the reliable answer.
Common questions
Is 1 MB 1000 KB or 1024 KB?
Both conventions are in use. Storage manufacturers, network speeds and macOS use decimal, where 1 MB is 1000 kB. Windows and most older tooling use binary, where 1 MB is 1024 KB. The IEC named the binary units separately, kibibyte and mebibyte, but the names never caught on outside standards documents.
How big is the difference at this scale?
About 2.4% between a kilobyte and a kibibyte, and 4.9% between a megabyte and a mebibyte. Small enough to ignore for a single file and large enough to matter when reconciling a storage quota or a transfer log.
What size should a web image be?
Under 200 KB for a full-width hero image and under 100 KB for anything smaller is a reasonable target on a page that needs to load quickly on mobile data. Modern formats make that achievable: the same photograph is typically 30% smaller as WebP than as JPEG.
Why is my email attachment rejected at 25 MB?
Because attachments are Base64-encoded for transport, which inflates them by about a third. A 20 MB file becomes roughly 27 MB on the wire, so a 25 MB limit is effectively an 18 MB file limit.
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