It depends on how many LEDs you have lit at once!
But a rough estimation is 20 milliamps per segment. Note that segments are multiplexed per row so that means
- 8x8 Mono Matrix (8 rows)= 8 x 20mA = 160mA max
- 7-segment backpacks (7 segments + 1 dot) = 8 x 20mA = 160 mA
- Alphanumeric (14 segments) = 14 x 20mA = 280mA
- Bi-color 8x8 and 8x16 matrix (16 rows) = 8 x 16 = 320mA
But again, this is maximum and assumes all digits and all segments are lit up! Your average use may be 1/10 to 1/2 of this amount