How to Date Antique Clocks

Measure the height of the clock. If the clock is at least 6 1/2 feet tall, it is a grandfather clock. The grandfather clock first became common in the 18th century.

Examine the face of the grandfather clock. A clock face with Roman numerals surrounded by an outer ring of Arabic numerals numbered from 5 to 60, in 5-minute intervals, indicates a clock from the period 1770 to 1800. Decoration from this period is also generally limited to simple corner designs.

Look for more complete face decorations in grandfather clocks from 1800 to 1830. The main clock face will usually feature the standard Arabic numerals, 1 to 12, with an outer circle that now shows only the numbers 15, 30, 45 and 60. Often, the face will also have simple floral or geometric designs in the center. A subsidiary moon dial may feature an elaborate painted scene.

Observe elaborate painted scenes on the faces of antique grandfather clocks from the period 1830 to 1870. The whole area around the dial will often be covered with images. The outer dial has disappeared, replaced by a single dial with Roman numerals from 1 to 12.

Observe the outline, or profile, of smaller mantel, table or wall clocks. Early 19th century American and English mantel clocks are generally in the form of rectangles, approximately 10 to 12 inches high and about half as wide.

Look for curves on the top of the clock case. Clocks in the form of an ogee, or curving and slightly indented arch, are from after 1840. Domed clocks from the 19th century are usually French clocks. Many feature domed glass covers that reveal the works inside the clock.

Follow the outer curves of a wall clock. Banjo clocks are named for their distinctive banjo shape and represent an American style that appeared at the beginning of the 19th century. Early examples are distinguished by decoration that consists of simple lines and semicircles, with delicate background colors and gold-leaf accents.