IP Range Calculator

Analyze IPv4 or IPv6 intervals with exact minimal CIDRs, containing-prefix spillover, overlap/adjacency comparison, batch aggregation and auditable exports — all in your browser.

Wave168 · exact address arithmetic, CIDR coverage & overlap evidence

IP Range & CIDR Planning Studio

Analyze an IPv4 or IPv6 start/end interval with exact 32/128-bit math, decompose it into the fewest exact CIDR blocks, compare a second range, normalize a batch plan, and export auditable evidence without sending addresses to a backend.

IPv4 + IPv6 · BigInt · browser-local

1. Primary range

Start IPEnd IPLoad CIDR / range / single IPDisplay policy

Ready.

2. Exact CIDR cover vs one-block containing prefix

Family—

Inclusive addresses—

Exact CIDR blocks—

Smallest one-block cover—

One-block spillover—

Cover utilization—

Range shape—

Endpoint type—

Minimal exact cover

#	CIDR	Start	End	Addresses

Containing-prefix evidence

3. Compare another range or CIDR

Expression B

Accepts a CIDR, a single address, or a start–end range. The result distinguishes identical, containment, partial overlap, adjacency and disjoint ranges.

4. Batch normalize & aggregate an IP plan

Ranges / CIDRs / addresses — one per line

Overlapping or touching ranges are merged within the same address family, then decomposed into an exact minimal CIDR set. A tab-separated label may precede an expression; labels are input context only and are not used to widen ranges.

#	Family	CIDR	Start	End	Addresses

5. Audit handoff

Recent local numeric summaries

Local history stores only numeric summary metadata — no IP addresses. The settings-only link excludes primary/secondary addresses, batch rows and history. CSV/JSON downloads intentionally contain addresses because they are explicit local handoff files.

Truth boundary. This Studio proves address arithmetic: inclusive interval size, exact CIDR coverage, one-block spillover, range relationships and normalized batch unions. It does not decide whether an address is usable in a specific subnet, apply cloud/firewall/DHCP reservation policy, validate live routing, guarantee that an ACL accepts the output, or replace authoritative IANA/RIR data. Endpoint type labels are practical known-range hints, not a complete registry classification.

Practical guide and verification

Use the tool above first. These notes explain how to interpret, verify and bound the result without displacing the primary workflow.

An IPv4 range is an integer interval

A start and end IPv4 address can be converted to 32-bit integers, making the inclusive address count equal to end minus start plus one. This is useful for checking whether a reported range size matches the actual endpoints.

CIDR coverage may need more than one block

An arbitrary start/end range is not always aligned to a single CIDR network. Minimal exact coverage can require several CIDR blocks chosen so none extend below the start or above the end address.

Common mistake

Do not call every address between two endpoints a usable host. Network and broadcast semantics depend on the subnet context, and special-purpose ranges have additional meaning. A plain range calculator does not assign routing or host roles by itself.

Verification

Confirm the first and last address of every proposed CIDR block, then ensure the blocks are contiguous, non-overlapping and cover exactly the requested interval. The sum of their address counts should equal the inclusive range size.

Operational boundary

Routing policy, firewall rules, DHCP pools and cloud-provider reservations can impose constraints beyond mathematical range coverage. Use the calculated interval as address arithmetic, then apply the rules of the actual network environment separately.