The first time I've ever taken one of these, I figured I was about 10 DPO and I got 3+
I went in for bloodwork a couple days later, since I hadn't had a period from BF'ing, and my Hcg was 800+. My OB just figured I was further along, but I knew differently. I knew I was expecting twins. An ultrasound a while later confirmed.
It was good at showing me my levels were high, but the range is still pretty low. You may have higher than average Hcg with a single baby, be further along, or have twins!
Edited to add:
I still had this on my desktop from when I was searching, LOL!
A combined precision/sensitivity study was performed where the candidate
device was challenged over 3 days, with 6 different operators who conducted
tests on 3 lots of devices. Twenty-eight urine standards were used in the study
in a range from 0 mIU/mL to 4621 mIU/mL hCG. The range of standards
tested incorporated a negative control, and hCG concentrations at the
“Pregnant 1-2” cut-off threshold (10 mIU/mL), “Pregnant 2-3” cut-off
threshold (156 mIU/mL), “Pregnant 3+” cut-off threshold (2600 mIU/mL),
and concentrations ± 20-80% of the thresholds. Only 3 operators conducted
testing on any one standard. Percentage results representative of data from all
three tested lots are provided below. Results were similar for each tested lot.