Static Address Reservation Planner
Allocate entered static address reservations.
Static Address Reservation 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.
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Network Address Calculator
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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 Static Address Reservation Planner Works?
The Static Address Reservation Planner works by placing each requested static reservation into the usable host range of a subnet, checking for conflicts, and reporting the addresses left for dynamic use.
Enter the subnet
Type the subnet, such as
192.168.20.0/24.List the reservations
Enter each role with its address count or explicit range: gateway, switches, servers, printers, and access points.
Place each block
The planner assigns blocks in order from the start of the usable range, or validates explicit ranges.
Report remaining space
The planner returns the remaining free range, ready for a DHCP pool.
Static Address Reservation Planner Formula
The Static Address Reservation Planner formula is Free Addresses = Usable Hosts − Σ Reserved Addresses.
Block size
Size = End − Start + 1For each reservation.
Total reserved
R = Σ Size_iSum of every reservation.
Free for DHCP
F = (2^(32−p) − 2) − RUsable hosts minus reservations.
Conflict check
Start_j ≤ End_i AND End_j ≥ Start_iDetects 2 overlapping reservations.
Worked example: 192.168.20.0/24
Usable hosts = 254 Reserved = 1 + 8 + 40 + 20 + 30 = 99 Free for DHCP = 254 − 99 = 155 DHCP pool = 192.168.20.100 – 192.168.20.254
Static Address Reservation Planner Conversion Table
The Static Address Reservation Planner conversion table shows a 6-row reservation plan for 192.168.20.0/24, with the range and size of each block.
| Role | Start | End | Addresses |
|---|---|---|---|
| Default gateway | 192.168.20.1 | 192.168.20.1 | 1 |
| Network switches | 192.168.20.2 | 192.168.20.9 | 8 |
| Servers | 192.168.20.10 | 192.168.20.49 | 40 |
| Printers | 192.168.20.50 | 192.168.20.69 | 20 |
| Access points | 192.168.20.70 | 192.168.20.99 | 30 |
| DHCP pool (remaining) | 192.168.20.100 | 192.168.20.254 | 155 |
What is Static Address Reservation Planner?
The Static Address Reservation Planner is a tool that lays out fixed address assignments for infrastructure devices inside a subnet and shows the space left for dynamic addressing.
Gateways, switches, servers, and printers need addresses that never change. Placing them in contiguous blocks keeps DHCP exclusions short and makes the address of each device predictable. A common layout puts infrastructure at the low end and the DHCP pool at the high end.
The planner checks every reservation against the usable host range and against the other reservations, which prevents overlaps before any device is configured.
What are the uses of Static Address Reservation Planner?
There are 4 main uses of the Static Address Reservation Planner, including site standards, DHCP exclusions, and device onboarding.
Defining site addressing standards
Every branch uses the same layout: gateway at .1, switches at .2 to .9, and printers at .50 to .69.
Preparing DHCP exclusions
The reserved blocks become exclusion ranges in the DHCP server.
Onboarding new devices
New printers receive the next free address in the printer block.
Documenting subnet layouts
The plan becomes the reference table in the site runbook.