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Inch fraction calculator

Convert decimal or fractional inches to a reduced fraction, rounded to the denominator you choose.

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Inch fraction calculator processes your input in this browser. Inputs and results are excluded from analytics. Recent tools save tool names, visit counts and last-visit times. Saved tools store only their names. Draft saving is optional and stays on this device; delete saved text with the draft controls. Loading text from a URL is optional and contacts that server; its URL and your IP address are visible to the server. An optional “Use in” action keeps a handoff in this tab. The next tool removes it on arrival and ignores it if more than a minute has passed.

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Answer

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Convert decimal or fractional inches to a reduced fraction, rounded to the denominator you choose.

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Precision and calculation record
Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.
Saved scenario
Save the current answer, then change an input to compare. This clears when you leave.
Formula and assumptions
Use a decimal, a fraction such as 5/8, or a mixed number such as 3 5/8. A leading minus applies to the whole value. Rounding ties go away from zero. The error shown is rounded value minus input, in inches. This represents a measurement; it does not change its accuracy.
Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.
Scratch calculator
Use +, −, ×, ÷, parentheses and %. A percentage is divided by 100. This does not change the main tool.
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Updated 
Using Inch fraction calculator
Convert decimal or fractional inches to a reduced fraction, rounded to the denominator you choose.
Use a decimal, a fraction such as 5/8, or a mixed number such as 3 5/8. A leading minus applies to the whole value. Rounding ties go away from zero. The error shown is rounded value minus input, in inches. This represents a measurement; it does not change its accuracy.
Next: Decimal to fraction calculator
Next: Length converter
A worked example
For inches (decimal or mixed fraction) = 3 5/8, rounding denominator = 16, rounded inches = 3 5/8.
Before you use the result
Use a decimal, a fraction such as 5/8, or a mixed number such as 3 5/8. A leading minus applies to the whole value. Rounding ties go away from zero. The error shown is rounded value minus input, in inches. This represents a measurement; it does not change its accuracy.
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ToolOctopus. “Inch fraction calculator.” Updated 2026-09-29. https://tooloctopus.com/inch-fraction-calculator.
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