There are many products purporting to clear up the complexities of your ovulation cycle, but mother nature (and the Starz network) has provided the most organic method. Throw away your urine sticks and your salivary testing kits, for the simplest way to chart your hormonal calendar is right at your fingertips. By taking note of your shifting physiological response to Outlander’s Jamie Fraser, you’ll be pinpointing your fertile days in no time.

Days 1-7: For what seems like centuries, certain friends have been recommending Outlander, hooked on its blend of time travel and hefty highland thighs. If your response to Sam Heughan as the rebel Scotsman James Fraser is neutral — if your pulse remains moderate and your glands nonreactive — then it’s clear that you are in the early days of your cycle. This is the follicular phase; menstruation is occurring, and ovulation is nowhere in sight. This stage may also include mild annoyance at your friends who hype these shows too much. They need to stop doing that.

Days 7-12: Warming up to Outlander can vary from individual to individual, but many experience this shift as “dramatic,” “sudden,” and “slippery.” Whether it begins with Claire and Jamie’s wedding night, or with the elaborate cunnilingus scene from season 1 episode 10, the estrogen uptick in the latter half of the follicular phase is marked by a noticeable fluctuation in the way you describe Jamie Fraser: from “okay if you’re into the himbos” to “a transcendent specimen of manhood.”

Days 12-13: This is a proliferative phase for your uterus, and your estrogen and luteinizing (LH) hormones are skyrocketing. If you’ve been monitoring your cervical mucus, you’ll notice a steep increase in fluids, especially when Jamie is straddled by a naked and dagger-wielding Claire beside a roaring fire, or whenever he calls her “Sassenach” with a filthy smirk playing about his lips. Other indications that ovulation is imminent: elevated basal temperature, quickening pulse, Scottish moaning.

Day 14 or 15 (appx): You are a swamp of hot, raging need. Your pupils are dilated. Your entire body salivates for Jamie. You cannea sleep; ye cannea eat. When you try to speak, your voice is a ragged whisper: “Do it now and don’t be gentle.” These are typical signs that an egg has been released and you are reaching peak fertility. If it’s a wee bairn you’re wanting, you’d better strike while the iron is hot.

Days 15-21: After the hormonal surge comes a fallow period; you may feel listless, vacant, lost in time, as if you are trapped for six long episodes in the twentieth century when really you belong in the seventeen hundreds, inside the arms (and kilt) of your fearless lover.

Days 21-28: You are adrift in the luteal phase of your cycle; you’ll recognize this time by its volatility. One minute you’re weeping for the lost years Jamie spent in prison; the next you’re furious at your own partner for not being a redheaded Jacobite who can outfox the British and knit a sweater. These are all tell-tale indicators that your progesterone levels are rising and falling as your endometrium prepares to slough off. Soon, a new cycle will begin.

Once you become familiar with your sympto-thermal pattern of responses to Outlander, you’ll develop a keen awareness of your fertile window. It may take a few cycles, but soon you’ll be able to auto-diagnose ovulation with accuracy. Then you’ll want to auto-diagnose again, and again, stroking your own armpit hair and whispering “Sassenach” to yourself in the bathroom mirror.