The conversion of Falna Points, or the total value of all stats layer by layer except magic, will show a person's power level.
I think this calculation of mine is very close and realistic.
Example:
Name: Bell Cranel
Level: 1
Strength: SS-1,091
Endurance: SS-1,019
Dexterity: SS-1,098
Magic: SS-1001
Falna Power Level: 227.25
All status except magic is equal to 4,545 Falna Points. Next, get the 5% which is 227.25. And since the average power level for humans is 5, let's say Bell has 4 as a base, and then add the points together, making it 231.25
And each time they level up, the FP stacks up by layer which also has a bonus of 5% increase from FP stacks.
Name: Bell Cranel
Level: 1→2
Strength: SS-1,091→I-0
Endurance: SS-1,019→I-0
Dexterity: SS-1,098→I-0
Magic: SS-1001→I-0
Falna Power Level: 227.25→454.5
Total FP: 4,545
FP Bonus: 4,545 × 5% = 227.25
Total PL: 458.5
Next
Name: Bell Cranel
Level: 2
Strength: SS-1,088
Dexterity: SS-1,094
Agility: SSS-1,302
Magic: A-883
Falna Power Level: 454.5→680.15
Total FP: 9,058
Total PL: 684.15
That's all. Each time they level up, they get 5% of the Total Falna Points they've accumulated in total which will be added to their total strength as a barrier for each layer of Level.
And they don't get their base power to increase because it isn't a part of the Falna.
Also, even if they have high power level, if they cannot properly use Ki, they cannot do things like Flash Steps or some movement techniques that uses Ki because Adventurers don't know how to use Ki except few individuals and do feats like obliterating a Goliath with a roar.
Example: Silver have a battle power of 2 million.
That means he can defeat Ryoumen Sukuna at his full power, though they will be equal with Sukuna being a curse user and a strong person while Silver can literally obliterate a Yellow Star.