I'm not sure from personal experience since I've only had BFN's but I found this online: (Not sure how accurate this is but hope it's helpful)
Not all pregnancy tests are created equal. They each have a different sensitivity of hCG that they need to detect in order to turn positive. It is highly recommend that you STAY AWAY from BLUE DYE tests as they are known for false positives, evap lines and have even given men positive results.
All tests should be discarded after 10 minutes. After 10 minutes the results can no longer be considered accurate so if you don't see a line until 10 minutes after you have taken the test you should retest.
First Response Early Result: detects 6.5 mlU of hCG
Early-Pregnancy-Tests.com: detects 10 mIU/ml hCG they also make a strip that detects 25mlU hCG
First Response Gold Digital 18mIU
CVS Test: 25 mIU/ml hCG
Clear Blue Digital: 25 mIU
Accuclear Pregnancy Test 25 mIU
Answer Pregnancy Test 25 mIU
CVS Early Result Pregnancy Test 25 mIU
Dollar Store/Tree (mini-strip, cassette, & midstream) 25 mIU
E.P.T. Digital Test 25 mIU
Equate (Wal-mart) 25 mIU (they are starting to go blue dye but there are some pink dye left on the shelves so check the packaging)
Right Aid Pregnancy Test 25 mIU
Target Brand Pregnancy Test 25 mIU (Target makes blue dye too so be careful)
Walgreen Digital 25 mIU
Target Stores: 50 mIUs hCG
First Signal one-step 25 mIU hCG (Wal-mart not to be confused with the $3.99 one)
