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Ubify Financial Advisory Board
FINANCIAL ANALYSTS & CPA REVIEWERS
About This Tool
The Fractional Drill Bit to Decimal & Metric Sizer converts imperial fractional bit sizes into decimal inches, exact millimeters, and closest standard metric shop tooling sizes.
### Conversion Formulas & Metric Equivalents Machining and woodworking operations require converting fractional drill callouts into decimal dimensions: - **Decimal Inch Equivalent**: $$\text{Decimal Inches} = \frac{\text{Numerator}}{\text{Denominator}}$$ - **Metric Millimeter Equivalent**: Using the international inch standard ($1\text{ inch} = 25.4\text{ mm}$): $$\text{Millimeters (mm)} = \text{Decimal Inches} \times 25.4$$ - **Closest Standard Metric Bit**: Rounds the calculated millimeter dimension to the nearest standard $0.5\text{ mm}$ metric drill increment: $$\text{Closest Metric} = \frac{\text{round}(mm \times 2)}{2}$$
### Worked Conversion Example Evaluating a standard $5/16\text{ inch}$ imperial drill bit: - **Fraction Input**: $5 / 16$ - **Decimal Inch Diameter**: $5 / 16 = 0.3125\text{ inches}$ - **Exact Millimeter Diameter**: $0.3125 \times 25.4 = 7.9375 \approx 7.94\text{ mm}$ - **Closest Metric Drill Size**: $8.0\text{ mm}$ (a difference of only $+0.06\text{ mm}$)
### In-Browser Processing & Privacy All conversions compute dynamically in your web browser. No workshop tooling inventories, hole diameters, or project specifications are uploaded to any server.
How to Use
- 1
Enter the fraction numerator in the first input (e.g. 5 for 5/16).
- 2
Enter the fraction denominator in the second input (e.g. 16 for 5/16).
- 3
Review the decimal inch diameter rounded to four decimal places.
- 4
Check the exact millimeter conversion and closest 0.5 mm standard metric drill bit.
Frequently Asked Questions
What is the standard tolerance between fractional and metric drill bits?
Fractional inch bits and metric bits often differ by tiny fractions of a millimeter. For example, 5/16" (7.94 mm) is 0.06 mm smaller than an 8.0 mm drill bit, which is often within acceptable clearance for standard through-holes.
Can this tool calculate wire gauge or letter drill sizes?
This calculator converts fractional inch sizes. Numbered wire gauge (1 to 80) and letter drill sizes (A to Z) use specialized lookup gauge tables.
Are any tool dimensions saved to an external database?
No. All conversions execute 100% locally in your client-side browser runtime.