Is a military duffel bag considered over-sized luggage?

Can you answer anc876’s question about Luggage?:

I’ve used my standard military duffel for deployments in the past, but was considering using it for leisure travel because it’s light and can hold more than a standard suitcase (I’m trying to avoid the extra fees for a second checked bag). I know the checked baggage allowance is 62 linear inches. Will I end up paying over-sized baggage fees if I check it?

Luggage Backpack With Wheels