The way you measure the benefit of claiming one dependent on your income tax return is by what's called an exemption amount. For 2016, one dependent/exemption is worth $4,050. The way one exemption works is to reduce a person's taxable income by $4,050. For example, if you had $30,000 in taxable income with one exemption for yourself, one exemption for your wife, and one exemption for a child, that would be three exemptions worth $4,050 each, or $12,150 for all three. Now, instead of being taxed on that $30,000 of income you would be taxed on $17,850, ($30,000 - 12,150).
If you want to see the exemptions on your 2016 Form 1040, look on Line 42 or your 1040 A, Line 26.
