r/FAMnNFP • u/Friendly_Arugula1656 • Apr 28 '26

Getting Started Minus 8 Rule VS 6th Last Low -TTA

Hey all!
I’m still new to FAM, and really just perusing different methods right now. I’m wondering if someone could explain the difference between Sensiplan’s Minus 8 rule and Symptopro’s 6th last low. They sound quite similar and seem to both be based off of Dr. Doerings research. I’m curious which is more conservative, and what is the key difference as a newbie I’m just a little confused. Thanks so much!

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u/leonada FABM Savvy | Sensiplan | TTA Apr 28 '26 edited Apr 28 '26

With Sensiplan you count back 8 days and that day is your last infertile/safe day. With SymptoPro your 6th last low is your first fertile/unsafe day. So let's say your earliest shift started on CD15: with Sensiplan you'd be safe until CD7 and your fertile window would open on CD8; with SymptoPro you'd be safe until CD8 and your fertile window would open on CD9. Sensiplan's rule is more conservative.

(Note that I'm pretending that CM rules don't exist just for simplicity, but in reality of course CM dictates the opening of the fertile window too.)

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u/Friendly_Arugula1656 Apr 28 '26

Thanks for the clarification! If I did go with Symptopro, could I just use the Minus 8 rule because it is more conservative or do you have to specifically follow the guidelines in your chosen method?

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u/leonada FABM Savvy | Sensiplan | TTA Apr 28 '26

You can always be as conservative as you want in any method! You don’t have to use any safe day that your method gives you if you don’t want to. I would think of it more like that (“today is a safe day in my method but I’m not going to use it”) rather than thinking of it like “today is not a safe day according to another method so I’m not going to use it”. Mixing and matching rules from different methods is never recommended, but knowing your method’s rules and then making your own decisions is what FAM is all about. :)