IP Calculator

IPv4/IPv6 subnet calculator with binary visualisation, VLSM, supernetting and overlap detection

SoftPerfect IP Calculator is a free desktop application for IPv4 and IPv6 subnet calculations. It provides detailed network and mask information, a binary bit visualisation showing all address bits with colour-coded network and host portions, and interactive subnet planning with a split/join bar chart for creating custom subnet layouts.

Additional tools include a VLSM calculator for allocating variable-length subnets based on host requirements, route summarisation for consolidating CIDR networks into summary routes, and overlap detection for identifying containment and identity relationships between networks.

Key features

Subnet calculator — Comprehensive IPv4 and IPv6 network details including CIDR notation, host ranges, broadcast address, wildcard mask, scope and class. Three input modes: Prefix, Hosts needed and Subnets.
Binary bit visualisation — Interactive display of all 32 (IPv4) or 128 (IPv6) address bits with colour-coded network and host portions. The boundary shifts as you change the prefix length.
Subnet planning — Enumerate subnets for any prefix, then split and join them on a proportional bar chart to design custom allocation layouts. Full undo and redo support.
VLSM calculator — Allocate variable-length subnets from a parent network based on named host requirements, minimising address waste. Displays remaining free space.
Route summarisation — Consolidate multiple CIDR networks into the smallest set of summary routes. Supports both IPv4 and IPv6.
Overlap detection — Compare a list of networks and identify containment, identity and overlap relationships, with a visual network map.
Export and import — Export subnet tables, VLSM allocations, summary routes and overlap results to CSV or HTML. Load networks from text files.
Cross-platform — Windows, macOS, and Linux.

Where IP Calculator is useful

Network design and planning — Plan IP address allocation for new networks or expansions. Use VLSM to assign right-sized subnets to departments, floors or VLANs without wasting address space.
Certification study — Visualise subnet boundaries with the binary bit display. Practice subnetting for CCNA, CompTIA Network+ and other networking exams.
Firewall and ACL configuration — Quickly look up network ranges, wildcard masks and broadcast addresses when writing access control lists or firewall rules.
Route summarisation — Consolidate contiguous networks into summary routes to simplify routing tables and reduce the number of advertised prefixes.
IP conflict auditing — Paste a list of subnets from different departments or sites into Overlap Detection to identify containment or duplication before they cause problems.
Documentation and reporting — Export detailed subnet tables, VLSM allocations or overlap analysis results to CSV or HTML for inclusion in network documentation.