3-1/2 inch in decimal and mm

The math

1. A fraction is its top number divided by its bottom number: 3-1/2 in = 3 + 1 ÷ 2 = 3.5 in.
2. An inch is exactly 25.4 mm, so 3.5 × 25.4 = 88.9 mm, or 88.900 mm to three places.
3. In feet, divide by 12: 3.5 ÷ 12 = 0.291667 ft. In centimetres, divide the mm by 10: 8.89 cm.
4. The same size in finer steps: 3-1/2 = 3-4/8 = 3-8/16 = 3-16/32 = 3-32/64. A tape marked in 16ths, 32nds or 64ths shows it at those marks.

Drills, plywood and lumber at 3-1/2 in

• 14/4 hardwood, rough
• 4x lumber, dressed dry

Every drill is on the drill bit size chart.

Sizes either side

Every size is on the fraction to decimal chart; any other size goes in the fraction to decimal calculator.