Assuming day one of your period was 1st July, then date of conception is July 15th. You need to know that these are approximate dates owing to the erratic nature of the menstrual cycle.
Here is a link to a pregnancy calculator:
http://healthlink.mcw.edu/article/923526833.html
This is great for working out a number of key dates in pregnancy.
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Pharmacist
MRPharmS. Worked as Community pharmacist for 16 years. Undertaking a second degree in medicine.