THE NUMBERS, EXPLAINED
How to use this calculator.
A user-supplied per-row model. Overhead is added to raw key-plus-pointer storage; it is not a fill factor. Excludes compression, variable-length keys, engine-specific headers, replicas and write-ahead logs.
Start with your inputs
Enter indexed rows, key bytes per row, pointer bytes per row, additional storage overhead (%). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Indexed rows | 1000000 |
| Key bytes per row | 16 |
| Pointer bytes per row | 8 |
| Additional storage overhead (%) | 25 |
A worked example
With the example inputs above, raw index bytes is 24,000,000. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Raw index bytes | 24,000,000 |
| Estimated index bytes | 30,000,000 |
| Estimated index (MiB) | 28.610229 |
How this is calculated
Raw index bytes
Rows × (key bytes + pointer bytes).
Estimated index bytes
Raw bytes × (1 + overhead percentage/100).
Estimated index (MiB)
Estimated bytes ÷ 1,048,576.
Symbols and units
- a
- Indexed rows
- b
- Key bytes per row
- c
- Pointer bytes per row
- d
- Additional storage overhead (%)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions and limits
A user-supplied per-row model. Overhead is added to raw key-plus-pointer storage; it is not a fill factor. Excludes compression, variable-length keys, engine-specific headers, replicas and write-ahead logs.
Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.
Questions about this tool
What does the result tell me?
Raw index bytes; Estimated index bytes; Estimated index (MiB). The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.
Why might another calculator differ?
Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: A user-supplied per-row model. Overhead is added to raw key-plus-pointer storage; it is not a fill factor. Excludes compression, variable-length keys, engine-specific headers, replicas and write-ahead logs.
Are my inputs stored or sent to AI?
Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.
Further reading
OpenStax: percentages and proportions ↗
Background reading; this does not imply endorsement or independent review of SumFizz.
Review status
Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.
Read the quality report →