According to the Masoretic Text of the Old Testament Goliath was six cubits and a span tall, 3.2 metres (9 feet, 6 inches), if measured by the 18 inch cubit, and 3.5 metres (just over 11 feet), if the 21 inch cubit is used. This is a height which is not only highly unlikely for any Iron Age man, but far beyond what would have been considered a giant at the time.
The New English Translation (2005), describes Goliath’s height as just under seven feet, significantly below the traditional height. A footnote in the NET explains the textual basis on which the translation committee made its decision.
The evidence of the Masoretic Text is dated very late, though this reading can be found in some earlier Greek translations of the Old Testament, as well as the Latin Vulgate. However, the textual evidence for a shorter height is more significant, being found in the oldest Greek and Hebrew texts. 
- The LXX: 6 feet, 9 inches
- 4QSama:  6 feet, 9 inches
- Josephus: 6 feet, 9 inches
- Lucian recension: 6 feet, 9 inches
- Codex Vaticanus: 6 feet, 9 inches
- Codex Alexandrinus: 6 feet, 9 inches
Modern scholarship prefers the reading of the earliest texts. A man of this height would still have been considered a giant in the Iron Age. Some reference sources cite medical conditions such as acromegaly which could have resulted in the height in the Masoretic Text, a suggestion found even in some professional medical works.
Although possible, it is unlikely such a man would have been an effective warrior given the disabilities typical of such conditions, and since acromegaly affects humans in middle age it would have been very rarely seen given the average Iron Age life expectancy of less than 40 years. 
 The medieval Hebrew text on which almost all modern English translations of the Old Testament are based.
 ‘Archaeology has shown that the heroes buried in the “royal tombs” at Mycenae were 1.76-1.80 mtr. tall, while the height of the average man at that period (according to the skeletons excavated) was 1.64 mtr. both in the Aegean lands and in Canaan.’, Margalith, ‘The Sea Peoples in the Bible’, p. 49 (1994).
 1 Samuel 17:4 Then a champion came out from the camp of the Philistines. His name was Goliath; he was from Gath. He was close to seven feet tall.
 ‘7 tc Heb “his height was six cubits and a span” (cf. KJV, NASB, NRSV). A cubit was approximately eighteen inches, a span nine inches. So, according to the Hebrew tradition, Goliath was about nine feet, nine inches tall (cf. NIV, CEV, NLT “over nine feet”; NCV “nine feet, four inches”; TEV “nearly 3 metres”). However, some Greek witnesses, Josephus, and a manuscript of 1 Samuel from Qumran read “four cubits and a span” here, that is, about six feet, nine inches (cf. NAB “six and a half feet”). This seems more reasonable; it is likely that Goliath’s height was exaggerated as the story was retold. See P. K. McCarter, I Samuel (AB), 286, 291.’, NET, footnote on 1 Samuel 17:4 (1st ed. 2005).
‘What is the evidence for the variant which reads six cubits and a span (9’9″)? All of the manuscripts of the MT have this reading. However, one should keep in mind that the earliest MT manuscript evidence that we have for 1 Samuel is the Aleppo Codex, produced in AD 935. Likewise, the Leningrad Codex, the Hebrew manuscript on which BHK and BHS are based, and thus the major Hebrew text on which most of our English OT versions are based, was completed in AD 1010. Thus there is no extant Hebrew text any earlier than AD 935 that puts Goliath at six cubits and a span.’, Hays, ‘Reconsidering the Height of Goliath’, Journal of the Evangelical Theological Society (48.5.705), (2005).
‘However, the variant reading “six cubits and a span” is probably much older than these MT manuscripts. Symmachus, for example, reflects the six cubits and a span height in his translation. Symmachus was a Jew who around AD 200 prepared a Greek translation of the OT for the Jewish community in Caesarea of Palestine. His goal was to produce a Greek translation that was an accurate translation of the Hebrew.7 The fact that he gives Goliath’s height as six cubits and a span is strong evidence that this variant reading was already present in the proto-MT or Vorlage to the MT, that is, the Hebrew text tradition that by this time had become the standardized text of the Jews. Likewise, Origen, in his Greek translation found in the fifth column of his Hexapla, includes the longer version of 1-2 Samuel found in the MT and also lists Goliath’s height as six cubits and a span.’, ibid., p. 705.
‘Jerome’s fourth-century AD Latin translation (the Vulgate), which appears to follow the Hebrew proto-MT faithfully, likewise puts Goliath at six cubits and a span. The Vulgate gradually grew in popularity in the Western churches and eventually became the “received text” for the Western churches, thus codifying the 9’9″ giant into Western culture.’, ibid., p. 705.
‘However, the textual evidence for the variant reading of “four cubits and a span” is significantly stronger.’, ibid., p. 706; Hays (pp. 705-706), notes that Codex Venetus, an 8th century manuscript (also known as ‘Codex Venetus 5’, a Greek manuscript of the Old and New Testaments), has the reading ‘five cubits and a span’ (8 feet 3 inches), but dismisses this as a rogue reading unsupported by any other textual evidence.
‘Thus the textual witnesses for the variant that cites Goliath’s height at four cubits and a span (6’9″) include: (1) 4QSama, the oldest extant Hebrew manuscript for this text; (2) Vaticanus, the oldest complete Greek codex of the Bible; (3) Josephus, a non-biblical first-century ad reference; (4) the Lucian Greek recension, a third-century ad witness; and (5) other early codices such as Alexandrinus.’, ibid., p. 705.
Commonly known as the ‘Septuagint’, a Greek translation of the Old Testament, completed no later than the mid-2nd century BCE.
One of the Hebrew copies of the book of Samuel found among the ‘Dead Sea Scrolls’, this text contains 1-2 Samuel, and although parts of the text are damaged, 1 Samuel 17:3-6 is not; this text dates to around 50 BCE and is the oldest Hebrew copy of this part of 1 Samuel, so it is significant that it has the shorter height.
 Josephus, ‘Antiquities of the Jews’, 6.171 (1st century CE); Josephus was a 1st century Jewish historian, and although it is not likely that Josephus had access to historical records of Goliath other than the Biblical texts, the height he gives demonstrates that this was already recorded in the Hebrew Bible by his day, long before the taller height.
 This is an early 3rd century revision of the LXX text.
 A significant 4th century Greek manuscript containing almost all of the Old and New Testaments.
 A significant 5th century Greek manuscript containing almost all of the Old and New Testaments.
 ‘Some commentators point to the huge size of Goliath’s spear, “with a shaft like a weaver’s beam” and “a point that weighed six hundred shekels” (about 15 pounds) and conclude that this huge spear size argues for a nine and a half foot tall Goliath. Likewise, they underscore the massive weight of his armor (125-130 pounds) and conclude that the size of the armor fits better with a 9’9″ giant than with a 6’9″ warrior.’, Hays, ‘Reconsidering the Height of Goliath’, Journal of the Evangelical Theological Society (48.5.708), (2005).
 ‘However, first of all, the text does not say that Goliath’s spear was as big or as long or as heavy as a weaver’s beam. It just says that the “shaft” (lit. “arrow”) of his spear was as (D) a weaver’s beam. Yagael Yadin points out that the comparison between Goliath’s spear and a weaver’s beam is not saying that the shaft of the spear was as big as a large timbered crossbeam of a loom. Rather, the narrator is describing a looped cord or rope that was attached to the spear that enabled a warrior to throw it harder and further. This looped cord looked somewhat like the cord loops of a weaver’s beam; thus the analogy.15 It has nothing to do with the size of his spear.16 Thus it also has no bearing on the size of Goliath. Likewise, the six hundred shekel (fifteen pounds) weight of the iron spearhead certainly would not require a ten foot tall giant to throw it..’, ibid., p. 708; spears were also commonly used to thrust at short range (requiring less effort), rather than thrown (note Goliath does not throw his spear).
 ‘Yadin provides pictures of a real weaver’s beam as
well as ancient paintings of soldiers from the ancient Near East holding such looped weapons.8 His evidence is so convincing that, as I point out, the majority of commentators on 1 Samuel follow Yadin.9’, Hays, ‘A Response to Clyde Billington’, Journal of the Evangelical Theological Society (50.3.515), (2007).
 ‘In the MT, Goliath’s height is given as “six cubits and a span” (1 Sam 17:4), which would be about nine feet and nine inches, a true giant. However, LXX Codex Vaticanus and the Lucianic recension, as well as 4QSama and Josephus (Ant 6.171) all give Goliath’s height as “four cubits and a span,” about six feet and nine inches. Since the expected tendency would be to exaggerate the height of David’s opponent, the latter reading, according to which Goliath would still be a giant (albeit among men), is to be preferred (see McCarter 1 Samuel AB, 286).’, Ehrlich, ‘Goliath’, in Freedman (ed.), ‘The Anchor Yale Bible Dictionary’, volume 2, p. 1073 (1996).
 A 6 foot 9 inch Goliath (2.05 metres), would have been at least 20 centimetres taller than the heroes found in Iron Age Mycenaen tombs, and 30-40 centimetres taller than the average Iron Age man; this proves that even the heroes of the time were only 10-15 centimetres taller than the average, and a man 30 centimetres taller than these heroes would have been a real giant, almost 40 centimetres taller than the average man (Saul need not have been more than 6 feet tall to be head and shoulders above all in Israel, and at 6 feet 9 inches Goliath would still have been significantly taller).
 A pituitary gland disorder resulting in giantism.
 ‘However, D. Kellermann suggests that Goliath’s symptoms in 1 Samuel 17 match those of pathological gigantism (a pituitary condition known as acromegaly), including a tunnel-vision type of visual defect, which David presumably took advantage of in defeating him. If so, then the MT reading need not be considered an exaggeration.’, Li, ‘Goliath’, in Arnold & Williamson (eds.), ‘Dictionary of the Old Testament: Historical books’, p. 356 (2005).
 ‘The biblical giant Goliath may have been afflicted with acromegaly.’, Ember & Ember, ‘Encyclopedia of Medical Anthropology’, p. 392 (2004).
 Aside from various deformities, digestive problems, and high blood pressure, premature death is also a danger with acromegaly.
 Nevertheless, evidence from an Egyptian tomb dated well over 1,000 years before Goliath does indicate that acromegaly could occur earlier in life even during the Bronze Age; ‘The remains of a large adult male, probably in his late 20s or early 30s, from a Fifth Dynasty tomb (2494–2345 BC)…This individual exhibits characteristics of pituitary gigantism’, Mulhern, ‘A probable case of gigantism in a fifth Dynasty skeleton from the Western Cemetery at Giza, Egypt’, International Journal of Osteoarchaeology (15.4.261), (2005).
 The Bible mentions a number of champions from Gath, some with physical abnormalities (2 Samuel 21:20, 1 Chronicles 20:6), all apparently related by descent from ‘Rapha’, possibly ‘the giant’ (2 Samuel 21:16, 18, 20, 22, 1 Chronicles 20:4, 6, 8), so it is more likely that Goliath’s height was the result of a family genetic trait than the result of a later medical condition.