There are digital forms of many of these test brands and non-digital tests, which have a high sensitivity for detecting pregnancy at 5-6 days before the missed period.
Pregnancy Test Sensitivity
To make a comparison between these ultra-sensitive pregnancy tests would be difficult. Almost all of them claim to be able to detect the presence of HCG in the urine at about 5-6 days before you expect to miss a period. Sometimes, you can get a faint line even earlier than that but, as every pregnancy has different levels of HCG in the urine, this can lead to false negative tests and the need to redo the test after a couple of days. This is why many of these tests come in packages of two or more test strips so you can retest after a couple of days to see if you are really pregnant. The HCG levels usually double about every 48 hours at this stage in the pregnancy so waiting a couple of days may make all the difference in the world. Be sure to use a first-morning specimen that has the highest concentration of HCG in it.