For my first ever chart at FF, I was using a mercury fever thermometer. My chart was a dogs' breakfast. Next chart I started temping vaginally AND using a digital BBT thermometer and the difference in just reading the chart is astounding. It truly does make a difference. Many will say that it doesn't but when you consider that even a shift of 0.03 is recognised by the software, entering temps without decimal places really doesn't make much sense to me!

Lisa