A megabytes to gigabytes converter should preserve the byte quantity between input and output. The worked comparison below shows what 1500 MB means, how it differs from 1500 MiB, and why neither result proves an actual file can be uploaded.
Choose the input unit before converting
NIST lists these decimal and binary definitions, and identifies one byte as eight bits. NIST binary prefixes and byte comparisons
| Unit | Name | Bytes per unit |
|---|---|---|
| MB | Megabyte | 1,000,000 B |
| GB | Gigabyte | 1,000,000,000 B |
| MiB | Mebibyte | 1,048,576 B, or 2²⁰ B |
| GiB | Gibibyte | 1,073,741,824 B, or 2³⁰ B |
Under these explicit definitions, 1000 MB = 1 GB and 1024 MiB = 1 GiB. The factors are not interchangeable. If a source displays “MB” without a clear basis, confirm what byte definition it actually uses before entering it as decimal MB.
The four unit choices here are byte quantities. A value in bits or a transfer rate is a different input; do not relabel it as MB or infer transfer duration from size alone.
Convert 1500 MB through bytes
Use the original quantity 1500 decimal MB:
1500 × 1,000,000 = 1,500,000,000 B
1,500,000,000 / 1,000,000,000 = 1.5 GB
1,500,000,000 / 1,073,741,824 ≈ 1.396983862 GiB
The GB result is exact; the GiB display is rounded to nine decimal places. The same byte quantity sits behind both outputs. This is a unit comparison, not compression or a change in the data.
Do not report 1500 MB / 1024 = 1.46484375 GB. That expression uses the binary step while retaining decimal labels. It is not the conversion of the specified 1500 MB to GB.
Compare a different input: 1500 MiB
Now change the input unit while keeping the displayed number 1500:
1500 × 1,048,576 = 1,572,864,000 B
1,572,864,000 / 1,073,741,824 = 1.46484375 GiB
1,572,864,000 / 1,000,000,000 = 1.572864 GB
These results are exact for the given input. The larger byte count means 1500 MiB is a different quantity from 1500 MB.
| Input | Preserved byte quantity | Decimal GB | Binary GiB |
|---|---|---|---|
| 1500 MB | 1,500,000,000 B | 1.5 | Approximately 1.396983862 |
| 1500 MiB | 1,572,864,000 B | 1.572864 | 1.46484375 |
Keep input value, selected unit, bytes and output unit visible together. A result labeled only “1.46” loses the basis needed to understand it.
Compare a declared limit using the same byte basis
Suppose an illustrative limit is explicitly 1600 decimal MB = 1,600,000,000 B. Both sample byte quantities are below it:
- 1500 MB uses 1,500,000,000 B.
- 1500 MiB uses 1,572,864,000 B.
That comparison applies only to the declared numeric limit. It does not inspect a file, confirm a service's unit convention or establish upload permission. Actual service requirements and the actual file byte count still need checking. Do not substitute a rounded GiB display for the exact-byte comparison near a limit.
Specify errors without inventing a file measurement
The example takes a finite nonnegative numeric quantity plus an explicit MB, GB, MiB or GiB input unit and output unit. Blank is not zero. Reject negative, nonfinite or unsupported-unit input; clear stale results when input becomes invalid.
Zero is a valid quantity when explicitly entered. Retain the calculation basis separately from display rounding. Fractional entered quantities are mathematical inputs, not proof of a measured whole-byte file count; do not silently round bytes and call them an inspected file size.
The native comparison worksheet should include source label/basis confirmation, entered amount/unit, conversion factors, preserved bytes, exact derivation, rounded display and any declared-limit reference. The local HTML example keeps the unit basis and exact byte derivation visible.
Copy this prompt for the converter specification
Prepare an original US-English local converter specification and native unit-basis/byte-audit worksheet. Do not implement or claim a working converter, inspect files or promise uploads.
Explicit units: MB = 1,000,000 B; GB = 1,000,000,000 B; MiB = 1,048,576 B; GiB = 1,073,741,824 B. One byte = 8 bits. Quantity must be finite/nonnegative and input/output unit explicitly MB/GB/MiB/GiB. Blank is not 0; reject negative/nonfinite/unsupported unit and clear stale output. Ambiguous source MB basis requires confirmation; no bits or transfer-rate relabeling.
Compute input*bytes-per-input-unit, then divide by bytes-per-output-unit. Show value/unit/bytes/factor/exact derivation and rounded display separately. Preserve byte basis, not rounded display, for further calculations. Fractional mathematical inputs not measured whole-byte file counts; do not silently round bytes into actual file evidence.
Audit: 1500 MB = 1,500,000,000 B = 1.5 GB ≈ 1.396983862 GiB rounded to 9 places. Different input: 1500 MiB = 1,572,864,000 B = 1.46484375 GiB = 1.572864 GB exactly. Do not output 1500 MB / 1024 as 1.46484375 GB. Hypothetical explicitly decimal 1600 MB limit = 1,600,000,000 B; both samples below that numeric limit, no actual upload permission or service check. No compression, duration, actual file inspection, integration or persisted-edit claim. Worksheet authoritative; implementation/keyboard/precision/boundary tests later.
Keep the units beside the result
The local HTML converter shows the selected basis, exact byte derivation and output labels together. NOS supports saving and rendering prepared HTML. Keep the maintained unit-basis worksheet and actual source records authoritative.
Explore NOS to present a prepared conversion. Report the byte basis with the number so the next comparison uses the same quantity.