What to Know Before You Buy a Basal Body Thermometer

Digital basal body temperature thermometers
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Basal body temperature thermometers are marketed and sold specifically for women trying to get pregnant. While charting your basal body temperature (BBT) is a good way to track ovulation, one of the biggest benefits to this method is the low expense.

It's unlikely that a fancy thermometer will help you get pregnant faster. The key to getting pregnant is timing sex for ovulation (if you aren't facing infertility). You don't need a special thermometer for that.

On some BBT thermometers, the packaging boasts of accuracy to 1/100th of a degree. For example, the reading will give you 98.63 degrees F instead of only 98.6 F. However, to chart your BBT and predict ovulation, you don't need this level of detail; all you need is an accurate reading to the tenth degree. This is available on almost every basal body thermometer.

Features of BBT Thermometers

Specialty BBT thermometers do have some features that add value. Digital BBT thermometers frequently have memory recall. This means you don't have to record your temp first thing in the morning. You can just turn the thermometer back on to get the last recorded temp.

A beep to indicate that the thermometer is finished is nice. When you’re taking your temperature before you’ve stepped out of bed, it’s easy to fall asleep with the thermometer in your mouth. The beep helps. A must-have in a BBT thermometer is accuracy to one-tenth of a degree. Two-tenths is not good enough for charting.

Pros and Cons of Digital BBT Thermometers

  • Easier to handle

  • No need to shake the night before

  • Shatterproof

  • Batteries must be replaced frequently

  • As batteries weaken, readings may be inaccurate

  • Don't always function reliably

If you're choosing between a digital and a glass thermometer, know that digital thermometers are easier to handle, don't need to be shaken prior to use, and are less fragile than glass thermometers.

However, the batteries need to be replaced more often than you might imagine, when used daily. You may get inaccurate readings for the month or so before the batteries start to die. And sometimes these thermometers just stop working for no good reason, even after only a few months of use.

Choose whichever appeals to you most. Just make sure you stick to the same thermometer over a month's time.

BBT Thermometer Costs

The average price of a digital BBT thermometer is about $20 to $30, although some cost as much as $60. But you can spend just $10 and still get a good-enough thermometer. It may not have all the features, though.

If you’re buying a glass thermometer, $10 or less is a good limit. For glass, you want one that is non-mercury. You don’t need one that is specially made for fertility. As long as the thermometer is easy to read to the 1/10th of a degree, it’s good enough for charting.

BBT Thermometers to Avoid

Before you buy, read some reviews—not because of the fertility features, but because many cheap digital thermometers don’t last long or don’t have easy-to-read displays. (This is important if you don’t have memory recall functions and need to read it in the dusk of the morning.)

Some BBT thermometers come with sample charts. The really expensive thermometers will track your temperature for you on an internal computer. You may or may not consider these features as a waste of money. It depends on how comfortable you are with charting.

You can find free fertility charts for tracking your BBT. You can also sign up for free fertility calendar services online. There are many fertility apps for your phone, too. The best ones have web- and phone-based features.

BBT Thermometer Options

If you're not ready to buy a new thermometer now, you might be able to get by with whatever you have at home. However, if you do want to buy a new one, these basal body thermometers are reasonably priced and have good features.

Smart Basal Thermometer by Femometer

  • Accurate to 1/100th of a degree
  • 300-day memory
  • 90 second read time 
  • Syncs to your phone via Bluetooth for ovulation prediction

i-Snow Med Multi-Function Digital Basal Thermometer

  • Accurate to 1/100th of a degree
  • 60-day memory
  • Back-lit display for early morning readings
  • Built-in alarm to help you remember when to take your temperature 
1 Source
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  1. University of Michigan Health. Basal Body Temperature (Bbt) Charting. October 8, 2020.

By Rachel Gurevich, RN
Rachel Gurevich is a fertility advocate, author, and recipient of The Hope Award for Achievement, from Resolve: The National Infertility Association. She is a professional member of the Association of Health Care Journalists and has been writing about women’s health since 2001. Rachel uses her own experiences with infertility to write compassionate, practical, and supportive articles.