Hi Jyoti,
The heart of an adult has a mass of 250350 grams (912 oz). It has thesizeof a fist: 12 cm inlength, 8 cm  wide, and 6 cm thick, although this description is disputed, and heart might be slightly large.

Hello,
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Normally Weight of an adult human heart will be from 250 to 300 grams.Most of the experts consider an adult human heart will be of 310 grams where as others believe it varies from age to age. But to be honest human heart will be in between 250 to 350 grams.
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Human heart will be in the size of a fist. It may be smaller then size of fist but it will be not be bigger then that.
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Human heart Normally ranges 5 inches in length.
It's thickNess will of 2.5 inches and its size i.e., width will be 3.5 inches.
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It is always said that a human heart is as big as a human fist. So your heart is as big as your fist is and so is mine. On an average, a human heart weighs about 310 grams which is roughly 11 ounces. It is 12 cms in length, 8 cms in width and 6 cms in thickness.