Technology & Internet Calculators
Subnetting, data, encoding and other technical calculators.
Tools for network and web work: IPv4 and IPv6 subnetting, how long a transfer takes at a given speed, and encoders and formatters for Base64, URLs, HTML entities and JSON. The encoders run in your browser on the text you paste.
Which Technology & Internet calculator do you need?
- Subnet details for an IPv4 addressSubnet CalculatorNetwork and broadcast addresses, mask and usable host range from an address and prefix.
- Subnetting an IPv6 addressIPv6 Subnet CalculatorNetwork prefix and address range for an IPv6 prefix length.
- How long a download will takeDownload Time CalculatorFile size divided by connection speed, handling bits vs bytes.
- Encoding or decoding Base64Base64 Encode Decode ToolConverts text to and from Base64.
- Making a URL safeURL Encode Decode ToolPercent-encodes or decodes URL components.
- Checking or tidying JSONJSON FormatterValidates and pretty-prints JSON.
Browse Technology & Internet Calculators by Type
Networking
6 calculators
- Broadcast Address Calculator
- IP Range Calculator
- IPv6 Subnet Calculator
- Network Address Calculator
- Subnet Calculator
All Technology & Internet Calculators
Bits, bytes and connection speeds
Connection speeds are quoted in bits per second (Mbps) while file sizes are in bytes (MB), and a byte is 8 bits. A 100 Mbps connection therefore moves at most about 12.5 MB each second — before protocol overhead — which is why downloads take longer than a naive "100 MB at 100 Mbps = 1 second" guess.
Technology & Internet Calculator Guides
Base64 Encoding Explained: What It Does and What It Doesn't
Base64 converts arbitrary binary data into a text-safe string using a 64-character alphabet — it's a format conversion for safe transport through text-only channels, not encryption or compression, and it makes data larger, not smaller, by roughly a third.
Read guideCIDR Notation Explained: What /24, /26, and Other Prefixes Mean
The number after the slash in CIDR notation (like the 24 in 192.168.1.0/24) is a bit count, not a percentage or a version number — it tells you how many of the address's 32 bits are fixed as the network portion, and every single bit of difference doubles or halves the number of addresses in the block.
Read guideHow IPv4 Subnetting Is Calculated
An IPv4 subnet's network address, broadcast address, and usable host range all come from applying the CIDR prefix as a bitmask to the IP address — with a special two-address exception for point-to-point /31 links.
Read guideHow IPv6 Subnetting Is Calculated
IPv6 subnetting works the same way as IPv4 — masking the address by a prefix length — but with 128-bit addresses instead of 32-bit ones, producing address counts so large they're shown as exact text rather than a rounded number.
Read guideHow Password Entropy Is Calculated (And Why Length Beats Complexity)
Password entropy — a measure of how hard a password is to guess by brute force — is calculated as length multiplied by the base-2 logarithm of the character pool size, and a longer password from a smaller character set can have MORE entropy than a shorter, more "complex-looking" password with symbols mixed in.
Read guideHow to Calculate a Subnet Mask, Network Address, and Usable Host Range
Given an IPv4 address and a CIDR prefix (like /26), the subnet mask, network address, broadcast address, and usable host range are all derived through bitwise AND/OR/NOT operations on the address and mask — not separate lookups, but four related outputs of the same underlying arithmetic.
Read guide