“In most women, the body’s normal temperature will increase slightly during ovulation, 0.5 to 1 degree Fahrenheit, and remain high until the end of the menstrual cycle,” Nicole A. Sparks, MD, an Atlanta-based obstetrician-gynecologist, tells Verywell Family. The rise in basal body temperature (BBT)—the term simply refers to your body’s temperature at rest—will happen at the same time as ovulation, so tracking it every morning is a good method to use to help establish your window of fertility. (But be aware that you may be fertile just before ovulation as well.) The best time to get this accurate BBT reading is first thing in the morning, before any other activity. Basal thermometers are able to read 1/10 or 1/100 of a degree, picking up the slight rise and fall that regular thermometers can’t show. When it comes to choosing a basal thermometer, you also want to find one that is easy to use, suits your needs, and fits your budget. We’ve rounded up the best basal thermometers to help you with your natural family planning journey. With Bluetooth capability that makes loading daily results into an organized chart unnecessary, the Easy@Home Smart Basal Thermometer is our best overall pick because it is beginner-friendly and works in conjunction with other fertility tracking products. The super-precise thermometer can read to 1/100 of a degree, picking up on the slight changes in your temperature. If you are new to charting, temping, and tracking your cycles, the Premom app will seamlessly sync, log, and organize your results, making interpretation clearer. You can store up to 30 results on the thermometer and unlimited results on the app, so you can skip writing down your temperature every day. However, if you do like to take notes instead of relying on the app, the backlit display includes your temperature, the date, and the time. It takes 90 to 120 seconds to get results, which can definitely be cumbersome in the morning. Price at time of publication: $40 Display: Digital | Response time: 90 to 120 seconds | Battery type: Lithium metal battery included The basal thermometer is easy to use and stores one previous reading in case you forget to write it down. The simple, straightforward approach is a non-intimidating way to ease into fertility tracking. Price at time of publication: $80 Display: Digital | Response time: Not listed | Battery type: Not listed To use the Ava tracker, simply wear it at night, and when you wake up in the morning, sync it to the app, which will do all your calculations for you. While you are snoozing, the Ava technology is collecting data every 25 seconds to help you narrow down your fertility window. From your temperature and pulse rate to your heart rate variability and sleeping patterns, the bracelet is consistently checking various physiological parameters that impact your fertility (that would be a headache to track on your own). While the price point is higher than other options, it is FSA and HSA eligible. Price at time of publication: $279 Display: No display, only app | Response time: Not listed | Battery type: Rechargeable The thermometer is free of buttons and switches, so all you have to do is pop it in your mouth, and within 30 seconds, you’ll have a precise result. Made to be discreet, the Femometer’s beeping sound can be adjusted to suit your needs. We think the app makes interpreting results much easier, but it does require a $10 monthly subscription. Price at time of publication: $50 Display: No display, only app | Response time: 30 seconds | Battery type: CR123A battery included We appreciate that the app doesn’t require a paid subscription, and while it doesn’t automatically sync, it gives you a safe place to jot down your results and read them throughout the month. Price at time of publication: $12 Display: Digital | Response time: 60 seconds | Battery type: LR41 battery The sensitive basal thermometer can detect 1/100 of a degree to offer a precise and accurate measurement. We love that you can add all of your results to the free app, which then can translate them into charts and graphs for easier interpretation. Price at time of publication: $40 Display: Digital | Response time: Not listed | Battery type: Not listed
What to Look for in a Basal Thermometer
Ease of Use
To track your basal body temperature accurately, you must use the thermometer every morning as soon as you wake up. For a product that requires that much use, you’ll want it to be as easy as possible to figure out. Some thermometers are more straightforward than others, and depending on your lifestyle, you may fare better with a set-it-and-forget-it style wearable tracker.
Budget
It is no secret that fertility and reproductive health management can be an expensive undertaking. Thankfully, quality basal thermometers are available at various price points. You can choose the features that fit within your budget and lifestyle without compromising on effectiveness.
Basal vs. Traditional Thermometers
“A basal thermometer and regular thermometer are very similar, but the biggest difference between a basal thermometer and a regular digital thermometer is that a basal thermometer will measure in very small increments sometimes to 1/100 of a degree,” Dr. Sparks says. Since the rise and fall of your temperature is so slight, a regular digital thermometer simply won’t be able to capture it.
Why Trust Verywell Family
Latifah Miles is a commerce editor at Verywell Family and has several years of experience shopping for the best products for parents, caregivers, and their families. She thoroughly researches and analyzes products to find the best options on the market. “Basal thermometers are not 100 percent accurate, so you don’t want this as the primary way you track ovulation,” she adds. “Many factors such as fever, sickness, stress, alcohol, or even interrupted sleep and travel zone time differences can affect the accuracy.”
