tech calculator
B-Tree/LSM Index RAM & Disk Overhead Calculator
Calculate indexing overhead size, storage requirements, and RAM block caches for B-Tree and LSM database engines.
Inputs
Database Setup
Table Schema Sizing
Secondary Indexes
Results
Total Index Size
6.37 GB
Total Storage Required
18.29 GB
Recommended RAM Cache
1.27 GB
Formula
Database Index size sizer
Index Size = (Leaf Nodes + Interior Nodes) × Page SizeEstimates leaf node capacity using page size, fill factors, and key column byte sizes.
Step by step
How the calculation works
- 1Select the database engine (PostgreSQL B-Tree vs RocksDB LSM tree).
- 2Enter the total number of table rows in millions.
- 3Define column size metrics: primary key size, row size, and secondary index variables.
- 4Set the index fill factor percentage (higher reduces size but triggers page splits during random writes).
Related guides
Learn more about this calculation
Guide
How to Use Do The Calculation Calculators: A Practical Step-by-Step Guide
Learn the fastest reliable workflow for using Do The Calculation calculators, reading results, checking formulas, and using save, print, share, and export actions correctly.
Guide
Understanding Calculator Formulas: How DTC Turns Inputs into Results
Understand how Do The Calculation formulas are presented, what the explanation blocks mean, and how to verify calculator logic before using a result in a real decision.
Sharding Guide
Database Sharding & Capacity Planning
Learn how to partition databases, map nodes, and estimate disk growth rates.