7 tools
Networking & Technology calculators
Networking & Technology calculators: Calculate IP subnets, password entropy, file transfer time and digital storage conversions.
Subnet arithmetic, data transfer, storage units and password search-space estimates answer separate questions. An advertised bitrate is not an achieved file-transfer rate.
What's the difference between a subnet mask and a wildcard mask?
A subnet mask marks the network portion of an address with 1 bits and the host portion with 0 bits; a wildcard mask is its exact bitwise inverse, used by some routing and access-control configurations instead of a subnet mask. Both describe the same /prefix, just inverted
Subnet Calculator
A /24 gives 254 usable hosts. Each step to a longer prefix roughly halves that count.
Inputs: CIDR prefix length, IP address, first octet, IP address, second octet, IP address, third octet, IP address, fourth octet
Open calculator →02Password Entropy Calculator
Length matters more than complexity: a longer password from a smaller character set often beats a shorter, more complex one.
Inputs: Password length, Character set used, Attacker's guessing speed
Open calculator →03Download Time Calculator
Connection speed is sold in bits per second; file size is shown in bytes. Confusing the two is the single most common estimate error.
Inputs: File size, File size unit, Connection speed, Speed unit
Open calculator →04Storage Converter Calculator
A decimal gigabyte (10⁹ bytes) and a binary gibibyte (2³⁰ bytes) differ by about 7%; that gap is why a drive's rated capacity looks smaller once formatted.
Inputs: Storage to convert, Starting unit, Requested unit
Open calculator →05Aspect Ratio Calculator
Resize an image, a video or a window without stretching it.
Inputs: Width (pixels), Height (pixels), New width (pixels)
Open calculator →06PPI (Pixels Per Inch) Calculator
Compare monitors and phones by sharpness, not by resolution alone.
Inputs: Horizontal resolution (pixels), Vertical resolution (pixels), Screen diagonal (inches)
Open calculator →07Bandwidth and Data Usage Calculator
Check whether a streaming habit fits inside a monthly data cap.
Inputs: Bitrate (Mbps), Hours per day, Days per month
Open calculator →Networking & Technology calculator results and examples
| Calculator | What it answers | Headline output | Worked example |
|---|---|---|---|
| Subnet Calculator | A /24 gives 254 usable hosts. Each step to a longer prefix roughly halves that count. | Usable host addresses | 254 |
| Password Entropy Calculator | Length matters more than complexity: a longer password from a smaller character set often beats a shorter, more complex one. | Entropy | 83.4 |
| Download Time Calculator | Connection speed is sold in bits per second; file size is shown in bytes. Confusing the two is the single most common estimate error. | Estimated transfer time | 0.4 seconds |
| Storage Converter Calculator | A decimal gigabyte (10⁹ bytes) and a binary gibibyte (2³⁰ bytes) differ by about 7%; that gap is why a drive's rated capacity looks smaller once formatted. | Converted value | 0.931 |
| Aspect Ratio Calculator | Resize an image, a video or a window without stretching it. | Ratio width part | 16 |
| PPI (Pixels Per Inch) Calculator | Compare monitors and phones by sharpness, not by resolution alone. | Pixels per inch | 108.8 |
| Bandwidth and Data Usage Calculator | Check whether a streaming habit fits inside a monthly data cap. | Data per month (GB) | 202.5 |
Where people go wrong with networking & technology numbers
At an assumed constant 100 megabits/s, five decimal megabytes takes 5 × 8/100 = 0.4 seconds before overhead. MB and Mb differ by a factor of eight; MiB adds a separate binary-unit distinction.
Definitions
Networking & Technology terms
- CIDR notation : glossary term
- The slash-prefix shorthand (e.g. /24) that states how many leading bits of an IP address are the fixed network portion. A smaller number after the slash means a larger network with more usable addresses.
- Password entropy : glossary term
- A measure, in bits, of how unpredictable a password is: the base-2 logarithm of how many equally likely passwords share the same length and character pool. Higher entropy means an exhaustive guessing attack takes longer on average.
- Subnet mask : glossary term
- A 32-bit value that marks which bits of an IP address are the network portion versus the host portion. A wildcard mask is its exact bitwise inverse.
Networking & Technology: related calculator categories
Common networking & technology questions
Why does a /24 subnet only give 254 usable addresses instead of 256?
The first address in the range is reserved as the network address and the last as the broadcast address, neither of which can be assigned to a device. A /24 has 256 total addresses, so subtracting those two reserved ones leaves 254 usable hosts
Is a longer password always better than a more complex one?
Length increases entropy faster than adding character types does. Entropy grows with the length exponent, not the pool size. A 16-character password using only lowercase letters can have more entropy than an 8-character password mixing every character type, while also being easier to remember
Why do password crack-time estimates vary so widely between sources?
The number depends entirely on the assumed attacker: an online login that's rate-limited to 100 guesses a second is a completely different threat than an offline attacker running a cracked password-hash database through specialized hardware at billions of guesses a second. Always check which scenario a quoted crack time assumes
Why is my downloaded file smaller in my speed test than my internet plan promised?
Internet speed is sold in bits per second. But file sizes and download progress bars are shown in bytes, and a byte is 8 bits. A 100 Mbps connection transfers at roughly 12.5 megabytes per second at best, before accounting for real-world overhead, which is a quarter of what the raw number suggests if you don't convert first
Why does my hard drive show less capacity than what I paid for?
Manufacturers advertise storage using decimal gigabytes (10⁹ bytes), the SI-standard definition, while most operating systems report capacity in binary gibibytes (2³⁰ bytes) but label them "GB." A drive advertised as 1,000 GB shows as roughly 931 GiB once formatted, a real unit-definition gap, rather than missing storage
Does a bigger character pool always increase entropy more than adding length?
Not necessarily: going from a 62-character pool to a 94-character pool (adding symbols) raises entropy per character by less than one extra character of length does at most common pool sizes, because entropy scales with the logarithm of pool size but linearly with length
Why do IPv4 addresses top out at 255 per octet?
Each octet is 8 bits, and 8 bits can represent 256 distinct values, 0 through 255. That ceiling is fixed by the IPv4 standard's 32-bit address size, split into four 8-bit octets, not an arbitrary limit
How many hosts are in a /24 subnet?
254 usable addresses, since the block has 256 and two are reserved for the network and broadcast addresses
Why is my download slower than the advertised speed?
Plans list speed in bits per second at best, and Wi-Fi, server limits and overhead reduce what you actually get
What makes a password strong?
Length and randomness. Each added random character multiplies the search space, and reused or predictable passwords are weak at any length