Common Unit Conversion Mistakes and How to Avoid Them
Most conversion errors are not difficult maths; they are unit errors. A missing prefix, a 1000-versus-1024 assumption, or a lowercase b can change the meaning of an otherwise correct number. Use these examples as a quick review before publishing a specification or comparing products.
1 min readPublished September 17, 2026Updated September 17, 2026
Decimal and binary storage units
Storage vendors normally use decimal prefixes: 1 GB = 1,000 MB and 1 MB = 1,000,000 bytes. Operating systems and memory tools may use binary units: 1 GiB = 1,024 MiB and 1 MiB = 1,048,576 bytes.
| Expression | Meaning |
|---|---|
| 1 GB | 1,000,000,000 bytes |
| 1 GiB | 1,073,741,824 bytes |
| 1,000 MB | 1 GB in decimal notation |
| 1,000 MB | about 0.931 GiB, not 1 GiB |
Bits, bytes and network rates
A bit is written with a lowercase b and a byte with an uppercase B. Eight bits make one byte, so a 100 Mbps connection has a theoretical maximum of 12.5 MB/s before protocol overhead. Mbps is not the same as MB/s.
8 bits = 1 byte
Convert the unit before comparing a network plan with a download speed.
Frequency, length and prefix mistakes
- 1 GHz = 1,000 MHz, not 100 MHz.
- 1 km = 1,000 m, while 1 cm = 0.01 m.
- Milliseconds, microseconds and nanoseconds differ by factors of 1,000.
- Do not compare a value until both numbers use the same base unit.
When a result looks ten, one hundred or one thousand times too large, check the prefix before redoing the arithmetic.
A four-step verification checklist
- Write the full unit, including its prefix and letter case.
- Decide whether the source uses decimal or binary definitions.
- Convert both values to a shared base unit.
- Keep enough precision for the decision, then round only at the end.
Quick answer
Frequently asked questions
Is 1,000 MB equal to 1 GB?
Yes under decimal storage definitions. It is about 0.931 GiB under binary definitions.
How do I convert Mbps to MB/s?
Divide by 8, then account for protocol overhead in real transfers. For example, 100 Mbps is 12.5 MB/s before overhead.
Should I round before or after converting?
Convert first and round at the end. Early rounding can move a borderline result across a limit.