Basal body temp discrepancies

Has anyone tracked their basal body temp and noticed a big temp difference in thermometers?

I started tracking mine every morning for the last 13 days and have noticed only low numbers in the mid to high 96s with the highest being 97.9 (ovulation?), then dropping again to 97.4.

So I decided to compare this digital basal thermometer with my other digital basal thermometer and there was a huge number difference! (Note: I did this test in middle of the day, so I'm not recording it or anything).

The one I've been using said 97.1 while the other themometer said 98.2! I tried it again and the first read 97.4 while the other read 98.6. These are obviously huge differences for charting as the low numbers could mean hypothyroidism (of which I have no real symptoms) or something else. Both thermometers seem to be working fine with no low battery indications.

Any advice on which one of these I should use, or what I should do? Charting is worthless if the numbers are way off.  

[Heather5]

Wow that is quite a difference! But I wouldn't say charting is worthless if the numbers are off, as long as you stick to one of the thermometers and it seems to perform consistently, then you'll still see a clear rise after ovulation and should be fine. That's why they say never to change thermometer in the middle of a cycle. Best of luck this month!

[medanza]

True. Although this morning I took two inconsistent reads in a row that were 97.3 and 97.7 - one showing a rise and the other not. My other thermometer read exactly 98 two times straight.

So I think the first thermometer (a Walgreen's thermometer) is off and I'll probably switch at the end of my cycle. I've been reading online that Walgreen's thermometers have caused other women problems too...?