Page Table Size Calculator
Calculate page table memory overhead based on page size and mapped address space.
About Page Table Size Calculator
The page table maps virtual addresses to physical frames. Each page of mapped virtual memory requires one Page Table Entry (PTE), typically 8 bytes on 64-bit systems. With standard 4KB pages, mapping 16GB of address space requires 4 million PTEs consuming 32MB of kernel memory. HugePages (2MB or 1GB) dramatically reduce this overhead by requiring far fewer PTEs for the same mapped range.
Formula
Page table size
page_table_size = (mapped_memory / page_size) × PTE_size
- M
- mapped address space
- P
- page size
- E
- PTE size in bytes
Worked example
With the default values below, Page Table Size Calculator returns Page Table Size of 32.00. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Mapped Address Spaceminimum 0.001 GB
- 16 GB
- Page Sizeminimum 4 KB
- 4 KB
- Page Table Entry Sizeaccepts 4–16 bytes
- 8 bytes
Results
- Page Table Size
- 32.00 MB
- Total Pages
- 4,194,304
- Memory Overhead
- 0.1953%
Step by step
- 1Total pages= 4194304
- 2Page table size= 32 MB
- 3Overhead percentage= 0.1953%
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Why do large-memory databases use HugePages?
HugePages reduce page table overhead by 512x (2MB vs 4KB pages) and eliminate TLB misses for the huge-page-backed memory, significantly improving performance for workloads that map tens or hundreds of gigabytes.
Can page tables consume significant memory?
Yes. A process mapping 1TB of virtual address space with 4KB pages needs ~2GB just for page tables. This is why large-memory workloads benefit enormously from HugePages.