The following tools can aid you while assigning IP addresses:
The IP Subnet Mask Calculator enables subnet network calculations using network class, IP address, subnet mask, subnet bits, mask bits, maximum required IP subnets and maximum required hosts per subnet.
NetBox is an infrastructure resource modeling (IRM) application designed to empower network automation. Initially conceived by the network engineering team at DigitalOcean, NetBox was developed specifically to address the needs of network and infrastructure engineers. NetBox is made available as open source under the Apache 2 license. It encompasses the following aspects of network management: