# Language Model compare probability scores between Length varying sentence

My question is : How can I compare Language Model(LM) score for two sentences with different lengths ?

Probabilities are < 1, and since LM scores for a sentence are multiple of probability of bigram or trigram, depending upon it's a bigram or trigram model, the probability of scores of longer sentences will mostly be smaller.

So, how should I normalize the value of scores according to length ?

I am pretty sure, atmost everyone after reading LM would have had same doubt. But I couldn't find much on internet.

Would appreciate for any leads on this.

$$PP((w_1, ...,w_N)) = \sqrt[N]{\dfrac{1}{P(w_1, ...,w_N)}}$$