The iPhone SE weighs 3.99 ounces (113 grams), which is just shy of a quarter pound.
Since the iPhone SE design is almost identical to the iPhone 5s, they are similar in weight as well. In fact, the iPhone SE weighs one (1) gram more than its predecessor.The smaller form factor and 4-inch screen net the iPhone SE some weight savings over its larger cousins. Here are weights for the current iPhone lineup compared:
iPhone SE: 3.99 oz (113 g)
iPhone 6: 4.55 oz (129 g)
iPhone 6s: 5.04 oz (143 g)
iPhone 6 Plus: 6.07 oz (172 g)
iPhone 6s Plus: 6.77 oz (192 g)