The Dallas Central Appraisal district has the lot dimensions on most of the homes listed on their website. Here is the link so you can search by address. http://www.dallascad.org/SearchAddr.aspx If you have any doubt to the accuracy of the measurements, you will have to either
1. find the survey if you got one when you purchased the home (it's a large blueprint with the drawing on the property showing all the easements and encroachments)
2. pay for a new one to be done
Let me know if I can assist you with either one.
2. You can also refer to your survey if you have one, (alternatively you could purchase a new one.)
3. Measure it yourself for approximate size.
I hope this helps. If you need additional assistance please feel free to call me at 214-675-6992 and I'll assist you if I can.
However, if you need to be absolutely sure that the measurements are accurate and/or exactly the location of the lot lines, then you do need a survey. You may be able to find posts driven into the ground from past surveys but if you need to be sure, a new survey is the way to go. If you apply for a loan or refinance the property, for example, the mortgage lender requires a new survey.