Rechner / Calculator

Summarise IPv4 networks – merge overlapping and adjacent CIDR blocks into as few prefixes as possible. Runs in the browser.

Split a network into variable-size subnets via VLSM – by host demand, with network, mask, range and broadcast. Runs in the browser.

Calculate MSS from MTU – including IPv4/IPv6 headers and tunnel overhead (PPPoE, WireGuard, IPsec, GRE, VXLAN). Runs in the browser.

Check colour contrast per WCAG – contrast ratio plus AA and AAA pass for normal and large text, with a live preview.

Calculate password strength as entropy in bits – including character space and estimated time to crack. Runs locally in the browser.

Analyse an IPv6 address and prefix – expanded and compressed form, network, first/last address, address count and /64 subnets.

Calculate download time from file size and bandwidth – ideal and realistic duration including overhead. Mbit/s, Gbit/s and MByte/s.

Check a switch’s PoE power budget – total load, free budget, utilisation and the maximum number of devices per PoE standard (af/at/bt).

Estimate a UPS runtime from battery voltage, capacity (Ah), efficiency and load in watts. Result in minutes and hours.

Calculate the power draw and cost of devices and servers – kWh and euros per day, month and year, including 24/7 operation.

Calculate the usable capacity of a ZFS pool – mirror, RAIDZ1/2/3 and stripe, including TB/TiB conversion, efficiency and fault tolerance.