Frequently asked questions

Unlike free apps, our monthly subscription helps protect you and your data. We will never sell your data - though you will have the option to help us further research in women’s health. Check our science page for more info. Birth control costs money both to make and supply. Our subscription fee means we can continue offering another hormone-free birth control option.

There are two subscription options: either an annual or a monthly subscription. Click here for pricing. We also offer a free demo mode once you have downloaded the app so you can get a feel for using Natural Cycles before committing to a subscription. Download the app for ios here and download for Android here.

If you want to use Natural Cycles with a thermometer, you will need to use a basal thermometer. These are more sensitive than regular fever thermometers as they show two decimals (e.g. 36.72°C / 98.11°F). The temperature changes during your cycle are small, yet significant. The good news is that you get a basal thermometer included when you sign up for our annual subscription (you can also buy one as an add-on to our monthly subscription). Basal thermometers are also available at some pharmacies/drug stores. You can now also measure overnight by using Natural Cycles with the Oura Ring.

Your temperature can be affected if you’re unwell, hungover, or have slept  > 2 hours more or less than usual.  When this happens, choose ‘exclude temperature’ when entering the temperature in the app . This way the measurement will not be used in the algorithm’s calculation. The algorithm also has a feature where it can detect deviating temperatures and automatically exclude them. Check out our User Manual for more info on what can affect temperature.

When you start using Natural Cycles, it can take some time to get to know you, which means you will have more red days (days when you need to use protection) at the start of your journey. This is to ensure that the app is effective, but once it has detected your ovulation you are likely to get more green days. With regular measuring, ovulation can often be detected in the very first cycle. Your green (non-fertile) days will continue to increase over time as the app gets to know you better.

The number of fertile/non-fertile days you get will vary. As every woman is different, there is no set number of red days — although we're only actually fertile for six days in any cycle. However, the number of red days you get depends on the regularity of your menstrual cycle and how often you input data into the app, as well as having a steady temperature. Give the algorithm time to learn your cycle and try to measure at least five days a week to increase the number of green days. You can expect more green days after the app has found your ovulation. The best way to increase green days is to measure your temperature most mornings.  Find out more about how Natural Cycles works.

It depends. If you are using non-hormonal birth control (condoms, copper IUD, etc.), you can get started right away. Hormonal birth control affects your cycle and temperature, so you need to stop using it before you can start Natural Cycles. However, you can try the app in demo mode before coming off hormonal birth control. After stopping hormonal birth control, cycle irregularities are common, speak to your gynecologist if you have any concerns. Find out if Natural Cycles could work for you.

Many of us do experience irregularities in our cycles from time to time. Natural Cycles is just as effective if you have irregular menstrual cycles (i.e. cycles lasting fewer than 21 days or greater than 35 days in length). If your cycle is very irregular, Natural Cycles may be less suitable for you, as you may be given more red days, (these red days are a safety buffer since ovulation day can change with irregular cycles). However, those with irregular cycles often find Natural Cycles a useful tool in tracking their irregularities and better understanding their bodies. Find out if Natural Cycles will work for you.

It’s not a problem. We all forget things, and we all have days when we don’t get enough sleep, oversleep, or are feeling under the weather. We recommend that you aim to measure your temperature at least five days a week. Frequently forgetting to measure will not change the effectiveness of the app, but you may get more red days as a result.

Natural Cycles is the first app of its kind to be FDA Cleared and CE Marked. Most other fertility apps assume your cycle is 28 days long. This means the fertile window they give you is not tailored to you. Our algorithm significantly reduces the risk of you being assigned an incorrect fertile day as it uses your personal data. This reduces the risk of unwanted pregnancy, or can help you plan pregnancy with greater precision. While some fertility apps make money from selling data for advertising, we never have, and we never will, sell our users’ data. Find out why women around the world choose Natural Cycles.

You can get started by purchasing a monthly or annual subscription here. You'll also need a basal thermometer, this comes free with our annual plan, or you can purchase one with our monthly subscription or from your local pharmacy. You'll have to wait for your thermometer to arrive before you can start with Natural Cycles. Or, if you have your own basal thermometer, you can get started straight away.

Absolutely. Natural Cycles goes beyond birth control, learning about your cycle also gives you the power of knowing when it’s the best time to conceive. NC° Plan Pregnancy tells you on the days when you are most fertile, and it can also let you know when it’s the optimal time to take ovulation or pregnancy tests. Once you log a positive test in the app, you can start using NC° Follow Pregnancy - here you’ll get regular updates on the progress of your pregnancy.

During your menstrual cycle your temperature rises after ovulation and then falls slightly when your next period comes, this is due to a change in your body’s hormone levels. The Natural Cycles’ algorithm analyzes your temperature and period data to find ovulation (you can also give the algorithm a boost by taking optional LH tests). The algorithm also takes into account other factors like sperm survival, temperature fluctuations, and cycle irregularities to identify ovulation and calculate your red and green days. Read more info on how the app works.

Yes. The effectiveness of Natural Cycles is supported by clinical evidence, which shows a typical use effectiveness rate of 93% and a perfect use effectiveness of 98%. Read more on the science behind our effectiveness.

Yes! For our US users, sign up for Natural Cycles as you normally would, and an itemized receipt will automatically be sent after your subscription purchase. This PDF receipt should have all the information needed for reimbursement. Simply download the PDF and share with your employer.

We have also partnered with FSAstores.com. You can visit their website to purchase Natural Cycles products using your FSA/HSA credit card.

Natural Cycles requires a basal body thermometer to work (this is a thermometer that shows two decimal places). You should measure in your mouth, first thing when you wake up, and before you get up and out of bed. Place the thermometer under your tongue, as far back as possible, and then turn it on. After the thermometer beeps, enter the reading in the app to get your daily fertility status.

We are CE Marked in Europe and FDA cleared in the US as a medical device for contraceptive use. We are now also listed in the ARTG in Australia and on the SMDR in Singapore. Our certifications have been granted based on mandatory clinical data that demonstrates that the effectiveness rate of Natural Cycles is 93% with typical use and 98% with perfect use (when using protection on each red day). Natural Cycles is the first app that has been assessed as a method of birth control in Europe and the US. Read more about our regulatory clearance here. 

If you’re breastfeeding, we recommend you start measuring as soon as you get your period back. How soon it returns depends on a number of factors, including whether you are breastfeeding part-time or full-time. You can read more on using Natural Cycles while breastfeeding here.

Once you have ordered your thermometer you can expect the following shipping times:

• 6 days for the United States (except Alaska and Hawaii)
• 5 days for the UK and Sweden
• 8 days for the rest of Europe & Oceania
• 10 days for rest of world except for Canada (12 days) and Brazil (14 days)

We ship thermometers all around the world, except to the countries of Mexico, Argentina, Colombia, South Africa, Saudi Arabia, the United Arab Emirates, and Chile. However, you can get your own basal thermometer and use it with the Natural Cycles app. Natural Cycles is cleared for contraceptive use in Europe, the U.S., Australia, and Singapore. Residents of other countries can use Natural Cycles as a fertility tracker.

Anyone over the age of 18 years with a menstrual cycle can use Natural Cycles. However, it is most suitable for women who are looking for an effective, natural method of birth control and are able to take their temperature most mornings. It’s also important that women who use Natural Cycles feel comfortable using protection (such as condoms) or abstaining from sex on fertile days. Using Natural Cycles does require a routine, so the better it suits your lifestyle, the more you will get out of it. Find out if Natural Cycles could work for you.

Natural Cycles is a regulated medical device that follows GDPR and we also have our own very heavy data security measures in place that include encryption. Protecting user’s information has always been a top priority for Natural Cycles and as sensitive data becomes more sensitive, we’ll continue to make sure your data is safe with us

Yes! It is now possible to use Natural Cycles with an Oura Ring. When using Natural Cycles with an Oura Ring, you do not need to manually measure your basal temperature anymore as the ring will measure your temperature trend data while you sleep. Visit our Oura and Natural Cycles page to get your hands on our exclusive Oura offer or learn more about how it works.