Look at line 8 of your Form 1040 to see if you took the standard or itemized deductions.
2018 Standard Deductions:
Single $12,000 (+ $1600 65 or older or blind)
Married Filing Separately $12,000 (+ $1300 65 or older or blind)
Married Filing Jointly $24,000 (+ $1300 65 or older or blind)
Head of Household $18,000 (+ $1600 65 or older or blind)