This list is incomplete; you can help by adding missing items. (August 2008)
US nuclear weapons of all types – bombs, warheads, shells, and others – are numbered in the same sequence starting with the Mark 1 and (as of March 2006[update]) ending with the W-91 (which was canceled prior to introduction into service). All designs which were formally intended to be weapons at some point received a number designation. Pure test units which were experiments (and not intended to be weapons) are not numbered in this sequence.
Early weapons were very large and could only be used as free fall bombs. These were known by "Mark" designators, like the Mark 4 which was a development of the Fat Man weapon. As weapons became more sophisticated they also became much smaller and lighter, allowing them to be used in many roles. At this time the weapons began to receive designations based on their role; bombs were given the prefix "B", while the same warhead used in other roles, like missiles, would normally be prefixed "W". For instance, the W-53 warhead was also used as the basis for the B53 nuclear bomb. Such examples share the same sequence number.
In other cases, when the modifications are more significant, variants are assigned their own number. An example is the B61 nuclear bomb, which was the parent design for the W80, W81, and W84. There are also examples of out-of-sequence numbering and other prefixes used in special occasions.
This list includes weapons which were developed to the point of being assigned a model number (and in many cases, prototypes were test fired), but which were then canceled prior to introduction into military service. Those models are listed as canceled, along with the year or date of cancellation of their program.
Bombs – designated with Mark ("Mk") numbers until 1968, and with "B" numbers after that. "Test Experimental" bombs designated with "TX".
Mark 1 – "Little Boy" gun-type uranium weapon (used against Hiroshima). (13–18 kilotons, 1945–1950)
Mark 2 – "Thin Man" plutonium gun design—cancelled in 1944
Implosion Mark 2 – Another Manhattan Project plutonium implosion weapon, a hollow pitimplosion design, was also sometimes referred to as Mark 2. Also cancelled 1944.
Mark 3 – "Fat Man" plutonium implosion weapon (used against Nagasaki), effectively the same as the "Gadget" device used in the Trinity nuclear test with minor design differences. (21 kilotons, 1945–1950)
Mark 4 – Post-war "Fat Man" redesign. Bomb designed with weapon characteristics as the foremost criteria. (1949–1953)
Mark 5 – Significantly smaller high efficiency nuclear bomb. (1–120 kilotons, 1952–1963)
Mark 6 – Improved version of Mk-4. (8–160 kilotons, 1951–1962)
Mark 7 – Multi-purpose tactical bomb. (8–61 kilotons, 1952–1967)
Mark 8 – Gun-assembly, HEU weapon designed for penetrating hardened targets. (25–30 kilotons, 1951–1957)
Mark 10 – Improved version of Mk-8 (12–15 kilotons, cancelled May 1952).
Mark 11 – Re-designed Mk-8. Gun-type (8–30 kilotons).
At the peak of its arsenal in 1988, Russia possessed around 45,000 nuclear weapons in its stockpile, roughly 13,000 more than the United States arsenal, the second largest in the world, which peaked in 1966.
Although India's nuclear programme and its details are highly classified, international figures suggest that India possesses about 150 nuclear weapons, with enough weapons-grade plutonium for another 150–200 nuclear weapons (2020 estimate). In 1999, India was estimated to have 800 kg of separated reactor-grade plutonium, with a total amount of 8,300 kg of civilian plutonium, enough for approximately 1,000 nuclear weapons. 
Israel is widely believed to possess a substantial arsenal of nuclear weapons and missiles, estimated at 75-130 and 100-200 warheads, but refuses officially to confirm or deny whether it has a nuclear weapon program, leaving the details of any such weapons unclear. Mordechai Vanunu, a former nuclear technician for Israel, confirmed the existence of a nuclear weapons program in 1986.
Unconfirmed rumors have hinted at tactical nuclear artillery shells, light fission bombs and missile warheads, and perhaps thermonuclear missile warheads.
The BBC News Online website published an article on 28 May 2008, which quotes former U.S. President Jimmy Carter as stating that Israel has at least 150 nuclear weapons. The article continues to state that this is the second confirmation of Israel's nuclear capability by a U.S. spokesman following comments from U.S. Defense Secretary Robert Gates at a Senate hearing and had apparently been confirmed a short time later by Israeli Prime Minister Ehud Olmert.
As of June 2019, Pakistan is believed to possess about 160 nuclear weapons. The specifications of its weapon production are not disclosed to the public.
The main series for nuclear transportation is Hatf.
On 25 May 2009, North Korea conducted a second test of nuclear weapons at the same location as the original test. The test weapon was of the same magnitude as the atomic bombs dropped on Japan in the 2nd World War. At the same time of the test, North Korea tested two short range ballistic missiles. The country tested a 7 kt nuclear weapon on 2 February 2013. On 3 September 2017, North Korea conducted an underground thermonuclear test which had an estimated yield of 100kt to 250kt, according to various sources.
South Africa built six or seven gun-type weapons. All constructed weapons were verified by International Atomic Energy Agency and other international observers to have been dismantled, along with the complete weapons program, and their highly enriched uranium was reprocessed back into low enriched form unsuitable for weapons.
^Kristensen, Hans M.; Norris, Robert S. (5 July 2017). "Indian nuclear forces, 2017". Bulletin of the Atomic Scientists. 73 (4): 205. Bibcode:2017BuAtS..73d.205K. doi:10.1080/00963402.2017.1337998.
^"India's Nuclear Weapons Program". nuclearweaponarchive.org. Retrieved 26 June 2012.
^"India's and Pakistan's Fissile Material and Nuclear Weapons Inventories, end of 1999". Institute for Science and International Security. Retrieved 26 June 2012.
^Normark, Magnus, Anders Lindblad, Anders Norqvist, Björn Sandström and Louise Waldenström. "Israel and WMD: Incentives and Capabilities." Swedish Defence Research Agency FOI-R--1734--SE December 2005 <"Archived copy". Archived from the original on 2007-07-07. Retrieved 2007-10-20.CS1 maint: archived copy as title (link)>
^The Samson option: Israel's nuclear arsenal and American foreign policy, Hersh, Seymour M., New York, Random House, 1991, ISBN 0-394-57006-5
^"Middle East | Israel 'has 150 nuclear weapons'". BBC News. 2008-05-26. Retrieved 2012-08-14.
^"Israel 'has 150 nuclear weapons'", BBC News Online May 28, 2008
^"Nuclear Weapons: Who Has What at a Glance". Arms Control Association. ACA. Retrieved 23 April 2019.
^"Global nuclear weapons". sipri. SIPRI. Retrieved 13 June 2019.
^"North Korea could have fuel for 48 nuclear weapons by 2015". The Daily Telegraph. 20 August 2012. Retrieved 8 November 2012.
CNS Resources on South Africa's Nuclear Weapons Program at the Library of Congress Web Archives (archived 2001-09-27) – indicates that "most international experts conclude that South Africa has completed its nuclear disarmament. South Africa is the first and to date only country to build nuclear weapons and then entirely dismantle its nuclear weapons program."