THE FEUTEX TOOLKIT

B-Tree Fanout and Height Estimate

Estimate fanout and balanced-tree levels from fixed key and pointer widths.

Computer Systems workspace● Runs in your browser

01 Your input

Page bytesbytesFixed page overheadbytesKey and cell overheadbytesChild pointer bytesbytesIndexed records

02 Your result

View or copy raw result data

Result data

Formulafanout=floor(usablePage/(key+pointer)); height≈ceil(log_fanout records)

Sources and model references

https://www.sqlite.org/fileformat.html

Worked example

Inputs

Page bytes: 4096 bytes
Fixed page overhead: 96 bytes
Key and cell overhead: 16 bytes
Child pointer bytes: 8 bytes
Indexed records: 1000000

Expected results

Approximate internal fanout: 166 children
Balanced level estimate: 3 levels

Load the example in the workspace to reproduce these results. Display rounding does not change the underlying calculation.

How to use this tool

Enter the labeled inputs in the indicated units.
Calculate and compare every output against the stated model assumptions.

Try this example

{
  "page": 4096,
  "overhead": 96,
  "key": 16,
  "pointer": 8,
  "records": 1000000
}

Accuracy and scope

Uniform full nodes and fixed key widths; generic B-tree approximation, not SQLite exact file sizing. Simplified analytical model; not a design recommendation or safety certification.

Is my data uploaded?

This tool runs locally in your browser. Input and output are not sent to a processing server. Copy or download your result before leaving the page.