When you say "value" do you mean what it is worth to the tax assessor? If so, visit the assessor's office and ask how they arrived at the assessed value.
If you mean "market value", ask a realtor who specializes in your area to do a Comparative Market Analysis(CMA). There is no cost involved. If you need to know the value for bankruptcy, divorce, etc; hire a professional appraiser as very often the other party will not accept a Realtor's CMA.
When a buyer tries to get a mortgage loan, his lender will send a paid appraiser to evaluate the inside as well as the outside like the tax appraiser. So, his answer will be different.
A few websites offer to show you the estimated value of your property on-line, but be skeptical of these, since they are based solely on mortgage data and tax appraisals.
A Realtor can give you an estimate similar to what the paid appraiser will do. We call these CMAs. These are also based primarily on sales data, modified to take into account the interior amenities and condition.
If you would like links to any of these sources on the web, just send me a message.
The best way is to talk to an agent that knows your market.
RE/MAX Bryan-College Station
You can use home valuation websites, however I will only use to get an idea of price.
Market value will be affected by square footage, # of bedrooms, # of bathrooms, location, amenities, etc....
I will be happy to get you in contact with a professional Realtor who is an expert in your community.