IPv4 Subnet Sizes Explained: /30 to /24 — Usable IPs, Netmask Table & Calculator

How many usable IP addresses do you actually get in a /29, /28 or /27? Short answer: total addresses minus two (network and broadcast) — and, if the block is routed to your server instead of configured on-link, you do not lose a third address to a gateway. Here is the full reference from /30 to /24.

IPv4 subnet size table (/30 to /24)

PrefixSubnet maskTotal IPsUsable (classic)Usable (routed)
/30255.255.255.252412
/29255.255.255.248856
/28255.255.255.240161314
/27255.255.255.224322930
/26255.255.255.192646162
/25255.255.255.128128125126
/24255.255.255.0256253254

Classic = the gateway lives inside the block (subtract 3). Routed = the block is routed to your server’s existing main IP, so only network and broadcast are lost (subtract 2). TinyServers delivers IPv4 add-ons as routed subnets.

Interactive calculator

Where do the “missing” IPs go?

The first address of every subnet identifies the network itself and the last one is the broadcast address; neither can be assigned to a host. In a classic on-link setup a third address is taken by the router/gateway. With a routed subnet the gateway is your server’s main IP — it sits outside the block, so every host address inside the block stays usable.

Kurz auf Deutsch: die Subnetzmaske für /27 ist 255.255.255.224 — die Tabelle oben listet die Subnetzmasken für alle Prefixe von /30 bis /24.

Which size fits your project?

For ordering details and worked examples, see Routed IPv4 subnets for VPS: when you need /29, /28 or /27.

FAQ

How many usable IP addresses are in a /27?

A /27 has 32 total addresses; network and broadcast are reserved, leaving 30 usable. On a routed subnet all 30 remain usable on your server, because no address is consumed by a gateway.

What is the subnet mask for a /29?

255.255.255.248 — 8 total addresses, 6 usable hosts.

Why do I lose 2 addresses in every subnet?

The first address identifies the network itself and the last is the broadcast address; neither can be assigned to a host.

Do routed subnets waste an extra IP on the gateway?

No. With a routed subnet the gateway is the main IP of your VPS, which sits outside the block, so every host address inside the block stays usable.

Next step: add a routed subnet to your server from the IPv4 add-ons page, or start with an NVMe VPS Romania plan from €2.48/month.

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