Конвертеры
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Конвертер дробных дюймов в мм.
Конвертируйте дробные дюймы в миллиметры и обратно. Введите 3 1/4, 3-1/4, 1/4 или 3.25 и получите точную сокращённую дробь.
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Try 3 1/4, 3-1/4, 1/4, 5/4 or 3.25.
Разбор
Как пользоваться
One inch is defined as exactly 25.4 mm, so every conversion here is exact up to the rounding you choose.
Accepted input formats: "3 1/4", "3-1/4", "1/4", improper fractions like "5/4", and plain decimals like "3.25".
Results are always reduced — you get 1/2, never 8/16, and a value that rounds up to a whole inch reads as 1, never 16/16.
Pick 1/16 for framing and general carpentry, 1/32 for cabinetry and joinery, and 1/64 for machining or fine woodwork.
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Cite this calculator
Canonical URL: https://mathify.one/ru/conversion/fractional-inches
Cite as: Mathify. (2026). Конвертер дробных дюймов в мм. https://mathify.one/ru/conversion/fractional-inches
Use Cases
DIY and woodworking projects
When working with imperial measurements on tools or plans, quickly convert fractional inches to millimetres for metric rulers or hardware.
Example: Convert 5/16 inch to mm to drill a hole with a metric bit.
Engineering and design
Switch between imperial and metric dimensions in CAD or technical drawings without manual calculation errors.
Example: Convert 2 3/8 inches to mm for a mechanical part specification.
Frequently Asked Questions
- How do I convert a fractional inch like 3 1/4 to millimetres?
- Enter '3 1/4' (with a space) or '3-1/4' (with a hyphen) into the converter. The tool will interpret it as 3 and 1/4 inches, convert to millimetres (82.55 mm), and also show the reduced fraction.
- Can I enter a decimal like 3.25 instead of a fraction?
- Yes, you can type '3.25' and the converter will treat it as 3.25 inches, convert to millimetres (82.55 mm), and also display the equivalent reduced fraction (3 1/4).
- What does 'reduced fraction' mean?
- A reduced fraction is one where the numerator and denominator have no common factors other than 1. For example, 2/8 is reduced to 1/4. The converter automatically simplifies fractions for you.
Tips & Common Mistakes
Tips
- Use a space or hyphen between the whole number and fraction (e.g., 3 1/4 or 3-1/4) for mixed numbers.
- For fractions only, just type like 1/4 or 3/16.
- Decimals are accepted too – type 3.25 and get the reduced fraction.
- Double-check your input format to avoid misinterpretation (e.g., 3-1/4 is not 3 minus 1/4).
Common Mistakes to Avoid
- Entering '3 1/4' without a space or hyphen (e.g., '31/4') – the tool may read it as 31/4 inches.
- Confusing decimal points with fraction slashes – use '.' for decimals and '/' for fractions.
- Assuming the result is rounded – the converter gives exact millimetre values based on 1 inch = 25.4 mm.
Last updated: August 13, 2026