Tip to tip on my fingers is about 8".
Thumb looks to be over by about an inch so use the formula at 7" plus 2" for the girth.
It's all guesstimation at this point as you don't have accurate measurements for length or girth

but that formula with accurate measurements is pretty spot on!
As mentioned by others I have also caught some bass that made up for in girth what they lacked in length and some long lanky bass that didn't do great on weight.
For instance, a 7.9lber I caught once was 1.5 inches longer than an 8.6lber I caught the following year, the 8.6 made up for it in girth! Carry a soft tape or spend $25 on a decent digital scale are the best ways.
Nice fish by the way
