How many points is LACK worth in Scrabble?

LACK is worth 10 points in Scrabble.

Is LACK a valid Scrabble word? Yes — 10 points

Yes, LACK is a valid Scrabble word worth 10 points.

Yes, LACK is a valid Words With Friends word worth 12 points.

LACK is a valid Scrabble US/CAN word worth 10 points:

L₁A₁C₃K₅

LACK is valid in Scrabble UK (World) —

L₁A₁C₃K₅

LACK is a valid Words With Friends word worth 12 points:

L₂A₁C₄K₅

You can make 7 words from lack according to the Scrabble US and Canada dictionary.