The minimal iso image will download packages from online archives at installation time instead of providing them on the install media itself. Downloading packages at install time reduces the size of the iso image to approximately ~40MB depending on architecture (see below), as well as providing only the packages needed for installation. The download time savings achieved by using a mini iso can be significant, as only current packages are downloaded, so there is no need to upgrade packages immediately after installation. The mini iso uses a text-based installer, making the image as compact as possible.
To use the mini iso image download mini.iso from one of the following links and burn it to a CD or USB drive.
For help with CD burning, see BurningIsoHowto
For help with USB drive burning, see Installation/FromUSBStick
For differences between Ubuntu release versions, please see Releases.
To install, boot your computer from the the mini iso and select "Install" at the prompt. You can then follow the instructions from the text-based installer. On the software selection screen, you can select from a number of collections of software such as different desktop environments (kde, xfce, etc), a multitude of different servers, multimedia creation tools, media center (mythbuntu), etc. You can also select "Manual package selection" which will take you to aptitude. You may also select nothing and just continue to finish the installation. If you selected nothing, upon reboot you will arrive at a cli prompt; from here you can fully customize your new system.
mini system in UEFI mode
While the minimal iso image is handy, it isn't useful for installing on UEFI-based systems that you want to run in UEFI mode. The mini iso lacks the proper files for booting the computer in UEFI mode. Thus, the computer will boot in BIOS compatibility mode, and the installation will be in BIOS mode.
You can use an Ubuntu Server amd64 iso file (64-bit) for 'mini installations' in UEFI mode. There is a compressed image file dd_text_16.04-UEFI-n-BIOS-4-pendrive-7.8GB.img.xz of such an installed system, that can be used as a start of a custom installation.
See this link: Installation/UEFI-and-BIOS/stable-alternative.
64-bit PC (amd64, x86_64) (Recommended)
Ubuntu 18.04 "Bionic Beaver" 64MB (MD5: 8388f7232b400bdc80279668847f90da, SHA1: cce936c1f9d1448c7d8f74b76b66f42eb4f93d4a)
Ubuntu 16.04 LTS "Xenial Xerus" 54MB (MD5: fe495d34188a9568c8d166efc5898d22, SHA1: 902731a64bf54a057ba266a32de5fbcc4c494fcf)
Ubuntu 14.04 LTS "Trusty Tahr" 37MB (MD5: 7297321c2fa6424417a548c85edd6e98, SHA1: e1e074b4302898698977c08013e0afe5c06245e2)
32-bit PC (i386, x86)
Ubuntu 18.04 "Bionic Beaver" 57MB (MD5: c7b21dea4d2ea037c3d97d5dac19af99, SHA1: a2a3b9c952ffa774ef77974e4e98ed5a9cdba2c8)
Ubuntu 16.04 LTS "Xenial Xerus" 48MB (MD5: 574fd244f5069f086065a23f7bdf604f, SHA1: 59211a88a125a7933c176365bb36b13197983ab7)
Ubuntu 14.04 LTS "Trusty Tahr" 31MB (MD5: a2502844750ecb6477d8fb4ff6b9aaf8, SHA1: d17c34ce716f13396040ccdc02d32482ed6b01a1)
64-bit PowerPC (ppc64)**
Ubuntu 16.04 "Xenial Xerus" 61MB (MD5: 9251739a80776d2ee6fcc2f1c85e5c70, SHA1: 49379230edb4d4445cdb33a48e67832695deaf54)
Ubuntu 14.04 LTS "Trusty Tahr" 41MB (MD5: 81e3a1d934e9c8b9809c3fe20c387aec, SHA1: 72250efd801ea109f6e7d5c2e035f4c7a23de95c)
32-bit PowerPC (ppc)**
Ubuntu 16.04 "Xenial Xerus" 45MB (MD5: e293ce4d41204e68dc3e570e544aa1cd, SHA1: 9452c0adce221ce2b3a0ac671b102aae9741c2f4)
Ubuntu 14.04 LTS "Trusty Tahr" 29MB (MD5: 959bd251ae4fcc4ea8457de555ddaf27, SHA1: 52d3c31ebd9710707eed0bfa318aa5b9ac3b59b4)
** Unofficial port, unsupported by Canonical
General link that seems reliable
This general link has worked for some years, and seems to be kept up to date. It helps you to find and download fully functional official Ubuntu mini.iso files