Identification

The Great Tit is a large and boldly marked tit. It has a black head with a large white cheek patch, a green back, blue-gray wings and tail with a single white wing bar, a black throat that extends down the belly as a narrow black ventral line, and yellow underparts. The sexes are similar in overall appearance, with females being duller overall and having less black below than males. Populations in central Asia ("Turkestan Tit"; see Systematics) have a gray back and pale underparts.

The Great Tit provides relatively few identification problems in much of its range, but in Asia, it overlaps with or is found adjacent to the ranges of other closely related and formerly conspecific species of Parus.

In Europe, the widely co-occurring Eurasian Blue Tit (Cyanistes caeruleus) is broadly similar in appearance, but the Great Tit can be distinguished by its larger size and black-and-white head (versus a white supercilium and blue crown in Eurasian Blue Tit).

In North Africa, the Great Tit may resemble African Blue Tit (Cyanistes teneriffae), which differs in having a prominent white supercilium and blue-gray upperparts. It may also resemble the yellow Coal Tit (Periparus ater) subspecies from the Atlas Mountains, ledouci, but the latter has the cheek washed pale yellow.

The Japanese Tit (Parus minor) of eastern Asia, whose range abuts that of Great Tit in eastern Siberia, is quite similar in appearance, but has a duller olive back and mostly whitish underparts (compared to the yellow underparts of adjacent subspecies of Great Tit).

Three very similar forms of Parus come into contact, or very near contact, with one another in central Asia and present a particularly challenging identification problem: the subspecies P. m. intermedius of the major subspecies group of Great Tit, found in northeastern Iran, the 'Turkestan Tit' subspecies group of Great Tit, formerly split as Parus bokharensis, found from southern Turkmenistan east to western China, and the subspecies ziaratensis, decolorans, and caschmirensis of the Cinereous Tit (Parus cinereus), which approach the former two taxa in Afghanistan and Pakistan. All three taxa have gray, rather than green, upperparts, and have whitish rather than yellow underparts.

Compared to subspecies intermedius of the Great Tit, subspecies caschmirensis of the Cinereous Tit has more sharply defined and whiter tertial edging, and more extensive white in the tail (outer r6 almost entirely white, r5 mostly white with dark inner web, versus inner web of r6 dark and only a small amount of white at the tip of r5 in intermedius) (1 Harrap, S., and D. Quinn (1996). Tits, Nuthatches and Treecreepers. Christopher Helm, London, UK. Close ). Compared to both P. m. intermedius and the Cinereous Tit, the 'Turkestan Tit' subspecies group is distinguished by size and shape, appearing about 20% relatively longer-tailed and having relatively heavier legs (1 Harrap, S., and D. Quinn (1996). Tits, Nuthatches and Treecreepers. Christopher Helm, London, UK. Close ). The 'Turkestan Tit' subspecies group also has a subtly larger white ear patch, usually a narrower black rear border connecting the throat and crown, and slightly paler gray upperparts. There are subtle differences in tail pattern: the 'Turkestan Tit' subspecies group has a more graduated tail, with the outer pair of feathers shorter, and it has the central rectrices pale gray with a darker central streak; the Cinereous Tit has the central rectrices more extensively dark, but this is variable by population; the 'Turkestan Tit' subspecies group has extensive white in r6 and mostly white r5, but with more dark inner webbing on r5 than in the Cinereous Tit.

The Green-backed Tit (Parus monticolus) of the Himalayas and China is perhaps the most similar to the Great Tit, but the ranges do not overlap, and the closest populations of Great Tit (the 'Turkestan Tit' subspecies group) lack bright yellow underparts like Green-backed Tit; Green-backed Tit also differs from the Great Tit in having two wingbars (versus one), and somewhat brighter upperparts.​