letter
F
6.528 mm · 0.257 in
F drill bit — 6.528 mm
The F bit measures 6.528 mm (0.257 in). The closest bits in the other series are 6.5, 16/64, #1.
- Diameter
- 6.528 mm
- In inches
- 0.257 in
- Cross-section
- 33.47 mm²
Closest in other series
Use this when the only bits at hand belong to another series. For tapping, prefer the slightly smaller bit over the slightly larger one — a hole can be opened up later, never closed.
One step up and down
letter
Metric bits state the millimetres outright, inch bits state sixty-fourths. Number and letter bits carry names inherited from old wire gauges, where no formula links the label to the size.
How to read this
- Inch bits are counted in sixty-fourths — 16/64 reduces to 1/4.
- Higher numbers are thinner; later letters are thicker, with A picking up above #1.
- An inch is 25.4 mm, so multiply the inch value by 25.4 to get millimetres.
- For tapping, drill with the bit nearest to the thread’s outside diameter minus its pitch.
Frequently asked questions
Q. How wide is the F bit?
6.528 mm, or 0.257 inches.
Q. What would I use from another series?
The closest are 6.5 (6.5 mm), 16/64 (6.35 mm), #1 (5.791 mm).
Q. Which threads can this size tap?
None of the metric threads in this table match closely enough.
Q. What is the cross-section?
33.47 mm².