There are quite a few factors to consider when dating furniture. You need to examine the way the furniture is put together, the tools used to make it and its design.
Inspect the outer and inner areas
Inspect the back of the furniture, inside the drawers and underneath it to look for flaws that indicate that it was made by hand. If it appears to be flawlessly made, it was likely made by machine and is dated after 1860.
Check for symmetry
Because it is very difficult to make exact replications by hand, check the legs, feet and other matching aspects of the furniture. If they appear to be identical, it is likely a machine-made, post-1860 piece.
Check for evidence of tool usage
Examine the furniture for signs of chisel marks, uneven surfaces from hand planes, marks from manual saws and marks from circular saws. The tools that were used can provide insight into the furniture's age.
Examine wood type
Although you cannot base your date exclusively on the wood type used, there are certain time periods that are closely associated with certain wood types. Many pre-1700 pieces used oak wood. During the 1700s, walnut and mahogany became increasingly common. Cherry and maple wood became prevalent throughout the 1800s, and oak had a resurgence in popularity in the 1900s.
Look for irregularities in the screws to determine whether they were made by a person or by a machine. Screws made by hand are likely made in the 1700s, while machine-made screws with handmade indentations are likely from the mid-1800s.
Look at the style
Although furniture replicas have been made throughout history, determining the time period a furniture style was popular can provide valuable context clues.