when I was pregnant, I had this phone app, it's called contraction calculator, and it's totally free. All you have to do is push start and stop, and it will time your contractions, and the length in between them, and give you the average length the contractions are and the time in between. I used this when I started going into labor, and I had an idea that I was because my contractions wouldn't go away no matter what I did, and they got stronger over time. But for me, my contractions started at 3 mins apart, 1 minute long, and stayed that way all through the labor and birth rather than getting closer together like it says in the books.