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IPv4-Mapped IPv6 Converter

Construct or decode mapped addresses.

IPv4-Mapped IPv6 Converter: inputs and results

Enter an IP address, CIDR prefix, or range. Then check its first and last address below.

Quick presets:

Calculated Boundaries & ParametersReady

Network Address192.168.1.0
Broadcast Address192.168.1.255
First Usable Host192.168.1.1
Last Usable Host192.168.1.254
Subnet Mask255.255.255.0
Wildcard Mask0.0.0.255
Total Addresses256
Usable Host Range254

Key Capabilities

  • •100% Client-Side: Zero telemetry or server latency.
  • •RFC Compliant: Exact 32-bit and 128-bit integer precision.
  • •Quick Copy: Instant access to CIDR, mask, and range bounds.
  • •Cross-Platform: Works on desktop, tablet, and mobile browsers.
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How IPv4-Mapped IPv6 Converter Works?

This tool works by placing the 32-bit IPv4 address in the last 32 bits of the IPv6 prefix ::ffff:0:0/96, or by extracting those 32 bits in the reverse direction.

  1. Enter an IPv4 or mapped address

    Type 192.0.2.1 to build a mapped address, or ::ffff:c000:201 to decode one.

  2. Convert the IPv4 octets to hex

    192 → c0, 0 → 00, 2 → 02, 1 → 01.

  3. Join into 2 groups

    The 4 hex bytes form groups c000 and 0201.

  4. Print all forms

    The converter shows the dotted form ::ffff:192.0.2.1, the hex form ::ffff:c000:201, and the full form.

IPv4-Mapped IPv6 Converter Formula

The formula is Mapped = 0xFFFF × 2^32 + IPv4, which places the IPv4 address after 80 zero bits and 16 one bits.

Mapped integer

M = 2^32 × 65,535 + IPv4_int

Prefix ::ffff:0:0/96.

Group 7

g7 = octet1 × 256 + octet2

High 16 bits of IPv4.

Group 8

g8 = octet3 × 256 + octet4

Low 16 bits of IPv4.

Reverse

IPv4 = M AND (2^32 − 1)

Valid only when the top 96 bits equal ::ffff:0:0.

Worked example: 192.0.2.1

g7 = 192 × 256 + 0 = 49,152 = c000
g8 = 2 × 256 + 1   = 513    = 0201
Mapped (hex)    = ::ffff:c000:201
Mapped (dotted) = ::ffff:192.0.2.1

IPv4-Mapped IPv6 Converter Conversion Table

The table maps 10 IPv4 addresses to their IPv4-mapped IPv6 forms, in dotted, hex, and full notation.

IPv4Mapped (Dotted)Mapped (Hex)Full Form
0.0.0.0::ffff:0.0.0.0::ffff:0:00000:0000:0000:0000:0000:ffff:0000:0000
10.0.0.1::ffff:10.0.0.1::ffff:a00:10000:0000:0000:0000:0000:ffff:0a00:0001
127.0.0.1::ffff:127.0.0.1::ffff:7f00:10000:0000:0000:0000:0000:ffff:7f00:0001
172.16.5.20::ffff:172.16.5.20::ffff:ac10:5140000:0000:0000:0000:0000:ffff:ac10:0514
192.0.2.1::ffff:192.0.2.1::ffff:c000:2010000:0000:0000:0000:0000:ffff:c000:0201
192.168.1.100::ffff:192.168.1.100::ffff:c0a8:1640000:0000:0000:0000:0000:ffff:c0a8:0164
198.51.100.7::ffff:198.51.100.7::ffff:c633:64070000:0000:0000:0000:0000:ffff:c633:6407
203.0.113.254::ffff:203.0.113.254::ffff:cb00:71fe0000:0000:0000:0000:0000:ffff:cb00:71fe
8.8.8.8::ffff:8.8.8.8::ffff:808:8080000:0000:0000:0000:0000:ffff:0808:0808
255.255.255.255::ffff:255.255.255.255::ffff:ffff:ffff0000:0000:0000:0000:0000:ffff:ffff:ffff

What is IPv4-Mapped IPv6 Converter?

The IPv4-Mapped IPv6 Converter is a tool that builds or decodes IPv4-mapped IPv6 addresses, the ::ffff:0:0/96 format that represents an IPv4 address inside the IPv6 address space.

RFC 4291 defines IPv4-mapped addresses for dual-stack hosts. A dual-stack socket that accepts an IPv4 connection reports the client as ::ffff:192.0.2.1. Applications, web servers, and logs then store IPv4 clients in IPv6 format.

IPv4-mapped addresses never appear on the wire as IPv6 packets. NAT64 uses a different prefix, 64:ff9b::/96 from RFC 6052, for translated traffic.

What are the uses of IPv4-Mapped IPv6 Converter?

There are 4 main uses of the IPv4-Mapped IPv6 Converter, including log decoding, application allow-lists, and database normalization.

  • Decoding server logs

    Dual-stack web servers log IPv4 clients as ::ffff:x.x.x.x. The converter extracts the IPv4 address.

  • Writing application allow-lists

    Applications on dual-stack sockets must match the mapped form, not only the plain IPv4 form.

  • Normalizing database records

    Mixed records collapse into 1 format before deduplication.

  • Debugging socket code

    Developers confirm that IPV6_V6ONLY settings produce the expected address form.