One of the first things I learned on weight watchers was how their point system works, and how to calculate points in my head without the “slider.” Their formula is “top secret” - although you can find it everywhere. Here it is on Wikipedia.

Their formula is:
Calories / 50 + Fat / 12 - Fiber / 5 (where Fiber is no more than 4)

My formula changes the fat divisor to 10, and the fiber limit to 5 - making it easy to remember and calculate in your head.

Example product:
Nature Valley Chewy Trail Mix Fruit & Nut Bar
140 Calories
4g Fat
1g Fiber

So, here it is:

• Take the calories, move the decimal point over by two, then multiply by two. 140 calories, move the decimal point to become 1.4, multiply by two to come up with 2.8.
• Take the fat, move the decimal point over by one. 4g fat, becomes .4. Add that to the calories = 3.2
• Take the fiber, move the decimal point over by one, multiply by two. 1g fiber, move the decimal becomes .1, multiple = .2. Subtract that from total = 3.

My calculation, done in head = 3 points.
WW calculation = 2.933, round up to 3.

Yay.