Total Address Count Calculator
Count addresses within a prefix.
Total Address Count Calculator: inputs and results
Enter an IP address, CIDR prefix, or range. Then check its first and last address below.
Calculated Boundaries & ParametersReady
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.
Related IPv4 Subnetting & RangeAll Tools
IPv4 Range Calculator
Find address boundaries from a prefix.
IPv4 Subnet Calculator
Calculate subnet details from address and mask.
Network Address Calculator
Find the subnet’s network address.
IPv4 Broadcast Address Calculator
Find broadcast addresses where applicable.
First and Last Address Calculator
Identify a range’s endpoints.
Usable IPv4 Host Range Calculator
Apply the selected subnet-use rules.
How Total Address Count Calculator Works?
This tool works by subtracting the prefix length from 32 and raising 2 to the result. The output counts every address in the block, including reserved ones.
Enter a prefix length
Type a value from /0 to /32, or a full CIDR block such as
10.0.0.0/19.Count the host bits
Host bits equal 32 − prefix. A /19 has 13 host bits.
Compute 2 to the host bits
Each host bit doubles the block. 2^13 = 8,192 addresses.
Express the size in /24 units
The calculator divides the total by 256 to show the block as a count of /24 networks. A /19 equals 32 × /24.
Total Address Count Calculator Formula
The formula is Total Addresses = 2^(32 − p), where p is the prefix length.
Total addresses
Total = 2^(32 − p)Counts every address, including the network and broadcast addresses.
Size in /24 units
Units = 2^(24 − p)Valid for prefixes /0 to /24.
Share of IPv4 space
Share = 2^(32−p) ÷ 4,294,967,296The full IPv4 space holds 2^32 addresses.
Worked example: /19
Host bits = 32 − 19 = 13 Total = 2^13 = 8,192 addresses /24 units = 8,192 ÷ 256 = 32 IPv4 share = 8,192 ÷ 4,294,967,296 ≈ 0.00019 %
Total Address Count Calculator Conversion Table
The table lists the total address count for 17 prefix lengths, with the host bits, the exponent form, and the size in /24 units.
| Prefix | Host Bits | Exponent | Total Addresses | Equal to /24s |
|---|---|---|---|---|
| /0 | 32 | 2^32 | 4,294,967,296 | 16,777,216 |
| /4 | 28 | 2^28 | 268,435,456 | 1,048,576 |
| /8 | 24 | 2^24 | 16,777,216 | 65,536 |
| /10 | 22 | 2^22 | 4,194,304 | 16,384 |
| /12 | 20 | 2^20 | 1,048,576 | 4,096 |
| /14 | 18 | 2^18 | 262,144 | 1,024 |
| /16 | 16 | 2^16 | 65,536 | 256 |
| /17 | 15 | 2^15 | 32,768 | 128 |
| /18 | 14 | 2^14 | 16,384 | 64 |
| /19 | 13 | 2^13 | 8,192 | 32 |
| /20 | 12 | 2^12 | 4,096 | 16 |
| /22 | 10 | 2^10 | 1,024 | 4 |
| /24 | 8 | 2^8 | 256 | 1 |
| /26 | 6 | 2^6 | 64 | 1/4 |
| /28 | 4 | 2^4 | 16 | 1/16 |
| /30 | 2 | 2^2 | 4 | 1/64 |
| /32 | 0 | 2^0 | 1 | 1/256 |
What is Total Address Count Calculator?
The Total Address Count Calculator is a tool that returns the number of IPv4 addresses inside a prefix, counting all addresses with no reservations removed. A /16 contains 65,536 addresses and a /8 contains 16,777,216.
Total address count is the raw size of a block. Usable host count is a separate value that removes the network and broadcast addresses. The Total Address Count Calculator gives the raw size, which matches the figures used by Regional Internet Registries (RIRs), cloud providers, and IPv4 address brokers.
Each step of 1 in prefix length doubles or halves the count. A /22 holds 1,024 addresses, a /21 holds 2,048, and a /20 holds 4,096.
What are the uses of Total Address Count Calculator?
There are 5 main uses of the Total Address Count Calculator, including IPv4 purchasing, cloud CIDR sizing, and capacity reports.
Pricing IPv4 transfers
IPv4 addresses trade per address on the transfer market. A /22 (1,024 addresses) priced per IP gives the total block value.
Sizing cloud VPC CIDRs
Amazon VPC accepts IPv4 CIDRs from /16 (65,536 addresses) to /28 (16 addresses). The count shows how much space each choice provides.
Reporting address inventory
Inventory reports total the address count of every allocated block to show the size of the managed estate.
Comparing RIR allocations
RIR policies set minimum allocation sizes, such as a /24 (256 addresses). The calculator compares a request against the policy size.
Teaching binary growth
Students see how 1 extra host bit doubles the address count from 256 to 512 and beyond.