Download Time Calculator
Estimates how long a file takes to download at a given speed.
Internet Tools
Tools for IP addresses, your browser, web links, and your connection: subnets, IP formats, bandwidth, download times, and campaign URLs.
All Internet Tools
Mbps to MB/s Converter
Converts internet speeds between Mbps, MB/s, and other units.
IPv4 Subnet Calculator
Network, broadcast, host range, and masks for any IPv4 block.
IPv6 CIDR Calculator
First and last address, size, and type of any IPv6 prefix.
CIDR to IP Range
CIDR block to start and end IP, and an IP range back to CIDR.
IP Address Converter
IPv4 to decimal, hex, octal, binary, and IPv4-mapped IPv6.
IPv4 to IPv6 Converter
IPv4-mapped, 6to4, and NAT64 forms of an IPv4 address.
IPv6 Compress / Expand
Shorten IPv6 addresses (RFC 5952) or expand them in full.
IPv6 ULA Generator
Random fd00::/8 /48 prefix and its first /64 subnets.
MAC Address Generator
Random MAC addresses in colon, hyphen, or Cisco format.
Random IP Generator
Random IPv4 or IPv6 addresses, public only or from a CIDR block.
IP Address Extractor
Pulls every valid IPv4 and IPv6 address out of any text.
Bandwidth Calculator
Speed for a data volume, website bandwidth, and GB/month vs Mbps.
What Is My User Agent
Shows and parses your browser's user agent string.
Screen Resolution Checker
Your screen size, viewport, pixel ratio, and display settings.
UTM Builder
Adds utm_source, utm_medium, and utm_campaign tags to links.
URL Extractor
Pulls every link out of text or HTML source.
Hreflang Tags Generator
Validated hreflang tags, Link headers, and sitemap entries.
IP addresses and subnets
The IPv4 Subnet Calculator gives the network, broadcast address, host range, and mask for any CIDR block, and the IPv6 CIDR Calculator does the same for IPv6. CIDR to IP Range works in both directions. To change how an address is written, use the IP Address Converter, IPv4 to IPv6, and IPv6 Compress / Expand.
The IPv6 ULA, MAC address, and random IP generators create addresses for labs and tests, and the IP Address Extractor pulls every IP out of a log file. All of this runs in your browser. No address is looked up online.
Your browser and links
What Is My User Agent and the Screen Resolution Checker show what your browser tells websites about your device. For marketing links, the UTM Builder tags URLs for Google Analytics, the URL Extractor collects links from text or HTML, and the Hreflang Tags Generator writes language tags for multilingual sites.
Bits vs bytes
Internet plans are sold in megabits per second (Mbps). File sizes and download managers use megabytes (MB and MB/s). One byte is 8 bits, so divide a speed in Mbps by 8 to get MB/s. A 100 Mbps plan tops out at 12.5 MB/s.
The Mbps to MB/s converter does this for any unit, the download time calculator turns a file size and a speed into a time, and the Bandwidth Calculator works out the speed a website or a transfer needs.
Why real speeds are lower
Advertised speeds are "up to" figures. Several things take a share before your data arrives:
- Protocol overhead: TCP/IP headers and acknowledgements use part of the bandwidth.
- Wi-Fi signal: distance, walls, and interference from other networks slow wireless links.
- Network congestion: evenings and busy shared connections cut the speed each user gets.
- Server limits: the site you download from may cap how fast it sends.
Frequently asked questions
Why does my 100 Mbps connection download at only 12.5 MB/s?
100 megabits per second divided by 8 bits per byte is 12.5 megabytes per second. That is the expected maximum, not a fault.
How long does 1 GB take to download at 100 Mbps?
About 80 seconds in ideal conditions.
What is a subnet mask?
It marks which part of an IP address is the network and which part is the host. In 192.168.1.0/24 the first 24 bits are the network, which leaves 254 usable host addresses.