Site Address Allocation Planner
Divide a parent range across sites.
Site Address Allocation Planner: 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 Planning, VLSM & CloudAll Tools
VLSM Calculator
Allocate differently sized subnets.
VLSM Allocation Validator
Check alignment, capacity, and overlaps.
Supernet Calculator
Find a covering parent prefix.
Exact CIDR Aggregator
Merge prefixes without adding addresses.
Route Summary Calculator
Summarize networks and identify included gaps.
DHCP Scope Calculator
Plan allocation boundaries within a subnet.
How Site Address Allocation Planner Works?
The Site Address Allocation Planner works by assigning each site a block size by site class, then placing the blocks from the parent range in largest-first order.
Enter the parent range
Type the organization or region block, such as
10.0.0.0/14.Define site classes
Set sizes such as headquarters /18, data center /19, large site /20, and small site /22.
List the sites
Enter each site and its class.
Allocate
The planner places each block on its boundary and reports the space left.
Site Address Allocation Planner Formula
The Site Address Allocation Planner formula is Start_i = ceil(Cursor ÷ 2^(32 − pᵢ)) × 2^(32 − pᵢ), with sites sorted by prefix length ascending.
Block size
2^(32 − p_i)By site class.
Aligned placement
ceil(Cursor ÷ Size) × SizeNo misaligned site blocks.
Space left
2^(32 − p_parent) − Σ sizesRoom for new sites.
Worked example: 10.0.0.0/14 (262,144 addresses)
HQ /18 → 10.0.0.0/18 DC /19 → 10.0.64.0/19 Large sites /20 → 10.0.96.0/20, 10.0.112.0/20 Small sites /22 follow from 10.0.128.0
Site Address Allocation Planner Conversion Table
The Site Address Allocation Planner conversion table allocates 9 sites across 4 site classes from 10.0.0.0/14.
| Site | Class Prefix | Block | Range | Addresses |
|---|---|---|---|---|
| Headquarters | /18 | 10.0.0.0/18 | 10.0.0.0 – 10.0.63.255 | 16,384 |
| Data center | /19 | 10.0.64.0/19 | 10.0.64.0 – 10.0.95.255 | 8,192 |
| London | /20 | 10.0.96.0/20 | 10.0.96.0 – 10.0.111.255 | 4,096 |
| New York | /20 | 10.0.112.0/20 | 10.0.112.0 – 10.0.127.255 | 4,096 |
| Karachi | /20 | 10.0.128.0/20 | 10.0.128.0 – 10.0.143.255 | 4,096 |
| Lahore | /22 | 10.0.144.0/22 | 10.0.144.0 – 10.0.147.255 | 1,024 |
| Dubai | /22 | 10.0.148.0/22 | 10.0.148.0 – 10.0.151.255 | 1,024 |
| Berlin | /22 | 10.0.152.0/22 | 10.0.152.0 – 10.0.155.255 | 1,024 |
| Toronto | /22 | 10.0.156.0/22 | 10.0.156.0 – 10.0.159.255 | 1,024 |
What is Site Address Allocation Planner?
The Site Address Allocation Planner is a tool that divides a parent address range among offices, data centers, and other sites, giving each site a block sized to its class.
A good site plan gives every site 1 contiguous block. Each site then advertises a single summary route, and every subnet at the site comes out of that block. Site classes keep the plan predictable: every small office gets the same /22.
Placing large blocks first keeps every block aligned and leaves the free space at the end of the parent range in 1 contiguous piece.
What are the uses of Site Address Allocation Planner?
There are 4 main uses of the Site Address Allocation Planner, including WAN design, SD-WAN rollouts, and acquisitions.
Designing WAN routing
Each site advertises its block as 1 summary route.
Rolling out SD-WAN
SD-WAN templates take the site block as an input.
Absorbing acquisitions
New sites from an acquisition get blocks from the remaining space.
Tracking regional capacity
Space left in the parent shows how many sites still fit.