TTC Basic Charting Rules - Basic Fertility Window Identification Rules - P+3 and T3

Oct 13, 2026

Upload by Oliver

TTC Basic Charting Rules explain how to identify the fertile window using cervical mucus observations and symptothermal temperature confirmation. The fertile window begins with the first sign of cervical mucus or moist/lubricative vaginal sensations after menstruation ends. Closure and ovulation confirmation require both the P+3 Rule and the T3 Rule, whichever occurs last, with clear exceptions using Slow Rise or Fallback Rise.

LanguageEnglish

CategoryForms

FormatPDF

Pages36

Reading Time13 min

AccessFree to download

Identify the Fertile Window

Basic Rules

P+3 Rule

T3 Rule

Example: Mark Peak Day and Meet P+3 Rule

Example: Meet the T3 Rule

Putting It All Together

Exception Rules

Slow Rise Rule

Fallback Rise Rule

©Copyr ight Jess ie Brebner 2020 [fertilitycharting.com.au](fertilitycharting.com.au) Chart To Conceive Learn to read the signs of your body and maximise every fertile day TTC BASIC CHARTING RULES ©Copyr ight Jess ie Brebner 2020 [fertilitycharting.com.au](fertilitycharting.com.au) Chart To Conceive Webinar Basic Symptothermal Method Rules for Trying To Conceive by Jessie Brebner. Published by Fertility Charting, Tugun, QLD 4224 AUSTRALIA [https://fertilitycharting.com.au](https://fertilitycharting.com.au) © 2020 Jessie Brebner All rights reserved. No portion of this guide may be reproduced in any form without permission from the publisher, except as permitted by Australian copyright law. For permissions contact: [support@fertilitycharting.com.au](support@fertilitycharting.com.au) [fertilitycharting.com.au](fertilitycharting.com.au) ©Copyr ight Jess ie Brebner 2020 Note: This guide is not sufficient when learning to chart for contraceptive purposes. TTC BASIC CHARTING RULES ©Copyr ight Jess ie Brebner 2020 IDENTIFYING THE FERTILE [fertilitycharting.com.au](fertilitycharting.com.au) WINDOW BASIC RULES 1. The fertile window opens at the first sign of any cervical mucus, or any moist/lubricative vaginal sensation after your period ends. 2. The fertile window closes and ovulation is confirmed when both the P+3 Rule and the T3 Rule have been met (whichever occurs last). Exception Rules: If the T3 Rule does not fit your temperature shift, you can use either the Slow Rise Rule, or the Fallback Rise Rule instead (but these exception rules cannot be combined). ©Copyr ight Jess ie Brebner 2020 BASIC RULES IDENTIFYING THE FERTILE [fertilitycharting.com.au](fertilitycharting.com.au) WINDOW P+3 RULE The P+3 Rule is met after 6pm on the evening of the third dry or non-peak day after the Peak Day. Remember, Peak Day is the last day you see any peak type cervical mucus/vaginal sensation followed by three dry/nonpeak days. It can only be marked retrospectively. THE T3 RULE The T3 Rule is met after 6pm of the evening when you can record three higher temperatures above six consecutive lower temperatures, with the third raised temperature being at least 0.2° C / 0.4° F higher than the highest of the six low temperatures. A coverline (a line drawn through the highest of the six low temperatures that precede the temperature shift can be helpful to visually check if you have met the T3 Rule. ©Copyr ight Jess ie Brebner 2020 IDENTIFYING THE FERTILE WINDOW [fertilitycharting.com.au](fertilitycharting.com.au) BASIC RULES EXAMPLE: HOW TO MARK PEAK DAY AND MEET P+3 RULE: Here you can see that Peak Day is marked on Cycle Day 14, even though this user only noticed a small amount of "eggwhite" style mucus. Peak Day is not the day with the most peak type mucus- it's simply the last day of peak-type observations. It must be followed by three consecutive non-peak or dry days. ©Copyr ight Jess ie Brebner 2020 IDENTIFYING THE FERTILE WINDOW [fertilitycharting.com.au](fertilitycharting.com.au) BASIC RULES EXAMPLE: HOW TO MEET THE T3 RULE: The coverline (in red) is drawn through the highest of the six low temperatures that precede the thermal shift. Here you can see that the T3 Rule is met on Cycle Day 21 because the third consecutive high temperature is at least 0.2° C above the coverline. IDENTIFYING THE FERTILE WINDOW BASIC RULES ©Copyr ight Jess ie Brebner 2020 [fertilitycharting.com.au](fertilitycharting.com.au) PUTTING IT ALL TOGETHER The fertile window opens at the first sign of any cervical mucus or moist/lubricative vaginal sensation on CD10 . The fertile window closes when ovulation is confirmed. To confirm ovulation, both the P+3 Rule and the T3 Rule must be met, whichever occurs last. The T3 Rule is met on CD17, and the P+3 Rule is met on CD19; therefore, ovulation is confirmed after 6pm on the evening of CD19 . ©Copyr ight Jess ie Brebner

FAQs

When does the fertile window open under these charting rules?

It opens at the first sign of any cervical mucus or any moist/lubricative vaginal sensation after your period ends.

What confirms ovulation according to the P+3 Rule and T3 Rule?

Ovulation is confirmed when both the P+3 Rule and the T3 Rule have been met, whichever occurs last.

What exception applies if the T3 Rule does not match the temperature shift?

If the T3 Rule does not fit your temperature shift, you can use either the Slow Rise Rule or the Fallback Rise Rule, but they cannot be combined.

Oct 13, 2026

Upload by Oliver