Inches to Fraction Calculator - Decimal to Fraction Inches Converter
Free inches to fraction calculator to convert any decimal to fraction inches. Convert mm to inches fraction, cm to inches fraction, or any length unit to fractional inches. Perfect for construction, woodworking, engineering, and DIY projects. Choose precision from 1/2 to 1/256 for accurate fractional measurements.
Last updated: January 23, 2026
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Choose the precision level for the fractional inches result
Fraction Result
Fractional Inches
12 1/2"
Decimal Inches
12.500000"
Millimeters
317.50 mm
Mixed Number:
12 1/2"
Conversion Tips:
- • Higher precision (1/64, 1/128) gives more accurate fractions
- • Lower precision (1/2, 1/4) gives simpler, rounded fractions
- • 1 inch = 25.4 millimeters exactly
- • Fractions are automatically simplified to lowest terms
- • Mixed numbers show whole inches plus fractional part
Inches to Fraction Calculator Features
Precision options
1/2, 1/4, 1/8, 1/16, 1/32, 1/64, 1/128, 1/256
Select the precision level that matches your measurement needs
Supported units
mm, cm, m, inches, feet, yards
Convert from metric or imperial units directly to fractional inches
Example
4/8 → 1/2, 16/32 → 1/2
Results are automatically simplified for easier reading
Use cases
Framing, Carpentry, Blueprint Reading
Convert measurements for construction plans and building projects
Applications
Furniture Making, Cabinetry, Home Projects
Get precise fractional measurements for woodworking and DIY projects
Engineering uses
Technical Drawings, Machining, Manufacturing
Convert decimal measurements to fractional inches for engineering specifications
Quick Example Result
For a distance of 12.5 inches with 1/16 precision:
Fractional Inches
12 1/2"
Decimal Inches
12.5"
Millimeters
317.5 mm
How Our Inches to Fraction Calculator Works
Our inches to fraction calculator converts decimal measurements to fractional inches by using a precision-based rounding method. The calculator first converts your input to inches (if needed), then applies the selected precision level to determine the nearest fractional representation. Fractions are automatically simplified to their lowest terms for clarity.
Conversion Formula
1. Convert to inches (if needed)2. Multiply decimal part × precision denominator3. Round to nearest whole number (numerator)4. Simplify fraction to lowest termsThe calculator uses the formula: numerator = round(decimal_part × denominator), then simplifies the resulting fraction using the greatest common divisor (GCD) algorithm.
Precision Levels Explained
Different precision levels divide each inch into different numbers of parts:
- 1/2 precision: Divides inch into 2 parts (0.5 inch increments) - simplest, least precise
- 1/4 precision: Divides inch into 4 parts (0.25 inch increments) - common for rough measurements
- 1/8 precision: Divides inch into 8 parts (0.125 inch increments) - standard construction precision
- 1/16 precision: Divides inch into 16 parts (0.0625 inch increments) - common woodworking precision
- 1/32 precision: Divides inch into 32 parts (0.03125 inch increments) - precise measurements
- 1/64 precision: Divides inch into 64 parts (0.015625 inch increments) - very precise
- 1/128 and 1/256: Ultra-precise measurements for specialized applications
Practical Applications
This calculator is essential for various real-world applications:
Construction & Building
Convert decimal measurements from blueprints to fractional inches for framing, cutting materials, and following construction plans. Essential for carpenters and builders.
Woodworking
Convert metric measurements to fractional inches for furniture making, cabinetry, and fine woodworking. Precision levels like 1/32 or 1/64 are ideal for detailed work.
Engineering & Manufacturing
Convert decimal measurements to fractional inches for technical drawings, machining specifications, and manufacturing tolerances. High precision (1/128, 1/256) for critical applications.
DIY & Home Projects
Convert measurements from metric tools (like metric tape measures) to fractional inches for home improvement projects, ensuring compatibility with imperial measurement systems.
Sources & References
- National Institute of Standards and Technology (NIST) - Guide for the Use of the International System of UnitsOfficial conversion factors: 1 inch = 25.4 mm exactly
- American National Standards Institute (ANSI) - Standard Fractional Inch MeasurementsStandard precision levels for fractional inch measurements in manufacturing
- Construction Industry Standards - Fractional Inch ConventionsCommon precision levels used in construction and woodworking (1/16, 1/32, 1/64)
Need other conversion tools? Check out our feet to inches calculator and length converter.
Get Custom Calculator for Your PlatformInches to Fraction Calculator Examples
Input:
- Distance: 12 millimeters
- Precision: 1/32
Conversion Steps:
- Convert mm to inches: 12 ÷ 25.4 = 0.4724 inches
- Whole inches: 0 (no whole inches)
- Decimal part: 0.4724
- Multiply by precision: 0.4724 × 32 = 15.12
- Round: 15.12 → 15
- Result: 15/32 inches
Result: 15/32 inches
12 millimeters equals 15/32 inches (approximately 0.4724 inches).
Decimal to Fraction Example
11.81 inches with 1/16 precision
= 11 13/16" (0.81 × 16 = 12.96 → 13)
7 mm to Fraction Example
7 mm with 1/32 precision
= 9/32" (0.2756 × 32 = 8.82 → 9)
Frequently Asked Questions
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