Charting is actually relatively easy and the good news there is a lot of tech on the market to help with it. I am going to assume that you all have mobile phones and know how to read them. You CAN chart on paper, but honestly….let the tech do the work for you!

What you need

My weapon of choice is the trusty Basel Body Thermometer. Baby Mad do one for around £5 on Ebay or Amazon but many companies do their own versions.


Next you’ll need an App.

Charting Apps

This can be Glow, Kindara, Clue, Conceivable, Ovia or Ovacue (which needs a fancy adaptor by the way) as well as Apple and Samsung Health. All are fine and most will track your temperature, cervical fluid AND moods then report to you after a few months on when you can expect to throw a vase at your housemate when she asks why you didn’t clean the kitchen. My absolute favourite however for pure simplicity and wealth of knowledge is Fertility Friend.

All however do the same job in essentials. Have a play and see which interface you prefer.

For most of these apps you don’t have to pay but if you want the added goodies (for when you’re trying for babies for example) it’s worth spending £15 on a subscription for a few months. Otherwise the basic app is fine.

Starting Charting

Your first challenge is getting up at the same time every morning and remembering to put the bloody BBT thermometer in your mouth. It takes a few days but soon you’ll be doing it practically in your sleep. I keep mine next to the bed so I can grab it blurrily and pop the temperature into my app.

Why does it have to be the same time every day?

Pure accuracy. You’ll see most apps will give you a closed circle if manage to temp around the right time you have set in your app. Otherwise you will get a round, open circle. This means the app will take this as a ‘rough’ temperature but will not assume it is accurate.

You also need to have had at least 3 hours of undisturbed sleep. Sounds easy? New mums trying to get their cycles straight will tell you this is trickier with a teething toddler and it’s also harder if you’re doing shift work.

You CAN temp with shift work but it’s harder. Fertility friend has some great info on their website here.

Ok, so you have put it in your mouth (or whatever) at your allotted time and pressed the button. It will bleep to say it’s ready. Take down the temperature, enter it into the app and that, folks is it. You are DONE for the day.

Do’s and Don’ts

Don’t use anything but a BBT thermometer for charting. It needs to measure to 00.00*F/C

Do try temping vaginally if you’re a mouth breather. It can make a difference. Just remember to clean the thermometer after use….

Do take your temp AS SOON AS YOU WAKE UP. Going to the loo doesn’t count. It needs to be your resting body temperature which means as soon as possible when you wake up.

Do log in the ‘extra information’ section of the app when you’ve had a very late night, a boozy night out the night before or are ill. It will make your temps appear higher and you can always chose to discount the temperature if you think it will affect the chart

What am I looking for?

Basically you are looking for a clear pattern.

This will feature low temperatures (your follicular phase) then a sustained temperature shift of at least 00.30* followed by raised temperatures (your luteal phase). The first point before your temperature rises is usually the day you ovulated and your app will confirm this using something called ‘Cross hairs’.

Those are the red crosses on the diagram below which was lovingly made in Paint by myself.

This is a bog standard chart of a healthy 34 year old woman with long cycles and a standard 14 day luteal phase. It’s actually mine:


As you can see, the vertical line shows where ovulation occurred. The horizontal line gives an indication of the low temperature in the follicular phase (the pink) and the high temperature in the luteal phase (the green).

It’s usual (but not mandatory) for there also to be a small dip before the temperature rise which can signify to the beady eyed as their ovulation. But if you have ovulated you will usually see this rise from lower temperatures. It’s not always as neat as this but you will see a sustained thermal shift if this has happened.

I told you. Black Magic.

How do I know this worked? Well, the temps say it did although it’s worth noting that the only way you can confirm ovulation is through an ultra sound and a blood test. In the case of this chart, I happened to be having some tests done around the time I ovulated and the nurse could see my ovary developing follicles. Which was pretty cool.

Still confused ? Fertility Friend have some amazing videos you can watch on their website. They are really worth checking out. Just click their name above.