Page Table Size Calculator
Calculate page table memory overhead based on page size and mapped address space.
Inputs
Standard 4KB or HugePages 2MB/1GB
8 bytes on 64-bit systems
Page Table Size
32.00MB
Total Pages
4,194,304
Memory Overhead
0.1953%
Step by step
Total pages
16 GB / 4 KB
= 4194304
Page table size
4194304 × 8 bytes
= 32 MB
Overhead percentage
page_table / mapped × 100
= 0.1953%
How it works
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
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.