You’ll need to check in with your body every single day. We’re talking temp-taking, mucus-noting, and calendar-updating. If you're more “vibes and winging it” than becoming a “daily data diva” might be a stretch.

In real life (where people forget things, sleep in, and go on holidays), it’s around 76-88% effective. So not ideal if a surprise pregnancy would be a major drama.

This method won't protect you from sexually transmitted infections, so if that's a factor, condoms are still your bestie.

Especially on fertile days when it’s either don't have sex or use some sort of barrier method like condoms. If your partner isn’t into planning (or condoms), there could be some unnecessary tension.

Stress and/or anxiety, sickness, jet lag, shift work, drinking alcohol and big nights out on the town, certain medications, exercising a lot, broken sleep - all of it can throw off your body’s cues. So if you’re in a chaotic life season, tracking may be trickier.

If your cycle likes to surprise you every month, it’s harder to spot the fertile window accurately. Not impossible, just more advanced level. Like level 100 on Candy Crush. 

If you are nearing menopause or have just started getting your period, this may not be the most effective method of contraception.

To use the calendar method as contraception, you need to track your cycle for at least 6 months first (so if you’ve been faithfully logging periods into your app, you’re already halfway there.)

Ovulation tends to happen about 14 days before your next period, but this is something you probably don’t want to just guess. To work out your fertile window, you’ll use your shortest and longest cycle lengths from the past 6-12 months, then calculate the earliest and latest days you could ovulate. Because sperm can survive up to 5 days and an egg for about 24 hours, you’ll want to steer clear of unprotected sex for several days before and just after ovulation.

Your app might colour these days red or give you a little warning icon. Avoid unprotected sex then, or use a backup method like condoms. Apps can make the maths easier, but choose one that’s actually designed for contraception, not just general cycle tracking.

This one’s for the morning people (or anyone who doesn’t mind a quick science experiment before coffee).

Before ovulation, your basal body temperature (BBT) is lower. After ovulation, it rises by around 0.2–0.5°C and stays higher until your next period. You won’t feel the change, it’s subtle but it’s a solid clue to where you are in your cycle.

To use this method:

• Get yourself a basal thermometer (more sensitive than a regular fever one).
  
• Take your temperature every morning before you move, scroll, or even think.
• Log it in your app or chart. Do this for a few months and you’ll start to see a pattern.

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Your fertile days are before the sustained rise in temperature. You can consider yourself in the infertile phase after your temperature has stayed higher for three mornings in a row. Those post-rise days are generally safer for unprotected sex.

A cute reminder: things like illness, alcohol, late nights, or travel can mess with your readings, so consistency is key.

Your cervical mucus is basically your body’s built-in fertility newsfeed. Throughout your cycle, your discharge changes in texture and appearance. You can check it by:

• Looking at your undies
• Wiping with white toilet paper before you wee
• Using clean fingers to gently check inside the entrance of your vagina
  
  

Then rub it between your thumb and forefinger like a curious scientist, you’re feeling for consistency.

The general pattern

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• Period: Hard to check mucus, so assume you’re fertile unless you know your usual “safe” pattern from tracking for a while.
• After your period: A few dry or sticky/creamy days. These can be safe if they’re your normal pattern and you’ve confirmed it over at least 3 cycles.
• Getting closer to ovulation: Mucus increases, feels wetter, and may be sticky, creamy, cloudy, or watery. These are fertile days.
• Ovulation (peak): Mucus is clear, slippery, and stretchy like raw egg white, or feels very wet - your most fertile time.
• After ovulation: Mucus thickens, gets tacky, or you go back to dry days. Count three days like this after your last fertile day before it’s considered safe again.

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Things that can throw you off: sex, semen, arousal fluids, infections, breastfeeding, or hormonal changes. Always check before sex, not after.

It’s best to track for at least three months before using this method as your main contraception, consistency and knowing your body’s “normal” is key.

Look for apps that let you manually input (or sync!) your basal body temperature (BBT), cervical mucus changes, and even cervical position. These are the real-time clues your body gives you about where you’re at in your cycle.

Some apps sync with BBT thermometers or wearable devices (like the Oura Ring or Tempdrop). If you know recording your temp every morning is just one step too many, this is a game-changer.

You want clear, customisable cycle charts that show you, your own patterns, not just random ovulation predictions or “fertile flower” emojis.

Your body is your business. Go for apps that prioritise privacy and don’t flog your data to marketers or serve you ads every time you log a symptom.

Avoid apps that try to predict your fertile days based solely on past cycles. You want a tool that helps you interpret your own data, not one that does it for you.