Unit Converter

Length Converter

Defined factors. Clear units.

Convert a length

Choose units and input method.

Entry method

Measurement

Use a signed decimal, scientific value, fraction or mixed number, such as 2 3/8.

From unit

To unit

View results

Precision and report

Display significant figures

Show rounded feet and inchesShow exact target ratioShow calculation stepsShow every-unit conversion table

Fractional inch subdivision denominator

Decimal inputs allow twenty significant digits and scientific exponents from negative thirty through thirty. Fraction components allow one hundred digits; an entire field allows two hundred forty characters. Negative values represent signed displacement rather than a physical size. Legacy survey measures are separately labeled.

Worked examples

Converted length in centimeters

y=30.4800\,\mathrm{cm}

Defined unit factors are exact. The displayed measurement is rounded to the selected significant figures; its physical accuracy still depends on the original measurement.

Conversion record

Source quantity

x=12.0000\,\mathrm{in}

Quantity in meters

x_{\mathrm m}=0.304800\,\mathrm m

Source unit meter factor

f_{\mathrm{source}}=\frac{127}{5000}

Target unit meter factor

f_{\mathrm{target}}=\frac{1}{100}

Source: Inches. Destination: Centimeters. Meter factors mean meters per one unit, not an extra measured input. Exact defined relationship. Exact defined relationship.

Rounded international feet and inches

x_{\mathrm{rounded}}=\left(1\,\mathrm{ft}+\left(0\right)\,\mathrm{in}\right)

\Delta_{\mathrm{mm}}=0\,\mathrm{mm}

The selected subdivision denominator is 16. Exact halfway cases round away from zero; a full inch carries into the next whole inch or foot. Signed error means rounded representation minus exact input. This representation always uses international feet and inches, including when a historical survey unit is selected elsewhere.

Length in every supported unit

All twenty-four rows represent the same entered quantity. Table values use the selected precision. Copy and CSV retain every row and its exact rational certificate even when this table is hidden.

Same quantity in twenty-four named length units
Unit convention	Converted quantity
Nanometers	$3.04800\times10^{8}\,\mathrm{nm}$
Micrometers	$304800\,\mathrm{\mu m}$
Millimeters	$304.800\,\mathrm{mm}$
Centimeters	$30.4800\,\mathrm{cm}$
Decimeters	$3.04800\,\mathrm{dm}$
Meters	$0.304800\,\mathrm{m}$
Decameters	$0.0304800\,\mathrm{dam}$
Hectometers	$0.00304800\,\mathrm{hm}$
Kilometers	$0.000304800\,\mathrm{km}$
Mils (thousandths of an inch)	$12000.0\,\mathrm{mil}$
Inches	$12.0000\,\mathrm{in}$
International feet	$1.00000\,\mathrm{ft}$
International yards	$0.333333\,\mathrm{yd}$
International miles	$0.000189394\,\mathrm{mi}$
International nautical miles	$0.000164579\,\mathrm{nmi}$
PostScript / CSS points	$864.000\,\mathrm{pt}$
PostScript / CSS picas	$72.0000\,\mathrm{pc}$
U.S. survey feet (legacy)	$0.999998\,\mathrm{ftUS}$
U.S. survey miles (legacy)	$0.000189394\,\mathrm{miUS}$
International chains	$0.0151515\,\mathrm{ch}$
International fathoms	$0.166667\,\mathrm{fathom}$
International rods	$0.0606061\,\mathrm{rd}$
International links	$1.51515\,\mathrm{link}$
International furlongs	$0.00151515\,\mathrm{fur}$

Step-by-step length conversion

1. Identify the input convention
Interpret the signed input exactly in the selected source unit. A decimal is not a feet-and-inches separator.
$x=12.0000\,\mathrm{in}$
2. Normalize to meters
Multiply by the exact defined meter factor. This step does not improve the precision of a physical measurement.
$x_{\mathrm m}=x f_{\mathrm{source}}=0.304800\,\mathrm m$
3. Scale into the destination unit
Divide by the exact destination factor and round once for the selected significant figures.
$y=x\frac{f_{\mathrm{source}}}{f_{\mathrm{target}}}=30.4800\,\mathrm{cm}$
4. Round the separate fractional-inch representation
Round the total absolute inches to the selected subdivision; exact ties go away from zero, then carry full inches into feet. The signed error is rounded representation minus exact input.
$\Delta_{\mathrm{mm}}=(x_{\mathrm{rounded,in}}-x_{\mathrm{exact,in}})\frac{127}{5}=0\,\mathrm{mm}$

What Can You Create?

Convert practical lengths with the unit convention visible

Everyday dimensions

Translate a product dimension, personal-height entry or room measurement between metric and international inch-pound units. Separate whole feet and remaining inches explicitly when reading a compound measurement, and use the same destination unit when comparing several specifications.

Workshop and print sizes

Read fractional inches, small metric dimensions, mils, PostScript points and picas without using a rounded intermediate value. Choose a ruler subdivision for the optional rounded representation and inspect its millimeter error before adopting it for a drawing or cutting instruction.

Distance and legacy records

Compare international miles, nautical miles, chains, links, rods and furlongs through an explicit meter route. Historical survey feet and survey miles have their own choices, helping you preserve a record’s original scale rather than silently treating every written foot as the same definition.

Exact factors, clear working

Length conversion formulas and worked examples

Let $x$ be the signed source value, $f_s$ the meters per source unit, and $f_t$ the meters per target unit. Each catalog factor is a fixed positive rational number. The route is $x_{\mathrm m}=xf_s$ followed by $y=x_{\mathrm m}/f_t$ . Conversion direction follows the unit factors, rather than a remembered instruction to move a decimal point.

y=x\frac{f_s}{f_t}

Example: the original inch conversion

For $x=12\,\mathrm{in}$ , use $f_s=127/5000$ and $f_t=1/100$ for centimeters. The exact result is $30.48\,\mathrm{cm}$ , while the meter record is $0.3048\,\mathrm m$ . More displayed significant figures add trailing presentation digits without changing either exact quantity.

12\frac{127/5000}{1/100}=\frac{762}{25}=30.48

Example: fractional inches and compound entry

A mixed value $2\frac{3}{8}\,\mathrm{in}$ means $19/8$ inches. It converts to $60.325\,\mathrm{mm}$ exactly. For compound entry, let $F$ be nonnegative whole international feet, $J$ remaining inches, and $s\in\{-1,1\}$ the selected sign. Then $x_{\mathrm{in}}=s(12F+J)$ . Five feet and ten inches gives $177.8\,\mathrm{cm}$ ; a decimal entry of $5.10\,\mathrm{ft}$ describes a different length.

\frac{19}{8}\times\frac{127}{5}\,\mathrm{mm}=60.325\,\mathrm{mm}

Example: a ruler subdivision and its signed error

For $180\,\mathrm{cm}$ the exact total inches are $9000/127$ . Rounding to the nearest sixteenth produces $5\,\mathrm{ft}+10\frac{7}{8}\,\mathrm{in}$ . That representation is $0.225\,\mathrm{mm}$ longer than the exact input. The main conversion stays unchanged; the separate error is $\Delta_{\mathrm{mm}}=(x_{\mathrm{rounded,in}}-x_{\mathrm{exact,in}})(127/5)$ . A negative error means the rounded representation is smaller in the signed coordinate convention.

\left(\frac{567}{8}-\frac{9000}{127}\right)\frac{127}{5}\,\mathrm{mm}=0.225\,\mathrm{mm}

Definitions that should remain distinct

An international foot is exactly $0.3048\,\mathrm m$ ; a legacy U.S. survey foot is exactly $(1200/3937)\,\mathrm m$ . International nautical miles use $1852\,\mathrm m$ . Here $1\,\mathrm{pt}=\frac{1}{72}\,\mathrm{in}$ and $1\,\mathrm{pc}=\frac{1}{6}\,\mathrm{in}$ , where the latter symbol denotes a pica. A mil is $0.001\,\mathrm{in}$ and is not a millimeter. Confirm the convention before interpreting a historical or specialized source.

Why Users Love This Tool

A conversion report you can inspect and reproduce

Preserve the entered numerical model

Defined rational factors avoid binary rounding in the conversion arithmetic.
A reduced exact target ratio and complete CSV certificates support independent checking.
Malformed input clears the old answer rather than being replaced by a plausible zero.

Control the form of the result

Choose three through ten significant figures for the primary result and every-unit table.
Inspect fractional-inch rounding separately from the original quantity.
Swap using the exact converted fraction, then share active settings for a reproducible comparison.

Perfect For

Useful for study, design and careful record reading

Students and teachers

Work through conversion direction with source and target meter factors visible. Check why linear factors differ from square-unit or cubic-unit factors, and distinguish a decimal foot from a feet-and-inches entry before comparing answers.

Makers and designers

Move between a supplied metric dimension and an inch-based ruler convention. The rounded representation includes a numerical error rather than suggesting that a coarser fraction is identical to the original value. This tool does not select a manufacturing tolerance.

Technical document readers

Preserve explicitly named legacy conventions when comparing a written distance. Unit conversion alone cannot infer map scale, ground distance, drawing calibration, datum transformation or the precision of an old instrument.

How It Works

How it works in three quick steps.

Identify the value and its unit convention

Choose one value with a source unit, or international feet and remaining inches. Decimal, scientific, simple-fraction and mixed-number syntax are accepted. In compound mode enter a nonnegative whole-foot count and a remaining inch quantity below twelve, then apply one sign to the complete measurement. Confirm whether a historical document uses survey feet before selecting a legacy unit.

Choose the destination and presentation precision

Select the output unit and three through ten significant figures. The converter routes the entered value through meters using defined rational factors, without rounding intermediate arithmetic. Optionally show its exact reduced ratio and a separate rounded feet-and-inches representation. Choose the fractional-inch subdivision to match a ruler or reporting requirement; that choice does not alter the main converted quantity.

Review the record and save the complete conversion

Inspect the source and target conventions, coherent meter quantity, all-unit table and generated working. Compare the signed error of any fractional-inch rounding. Swap units to retain the exact quantity, copy text or LaTeX, export CSV, share active settings or print the report. An exact conversion factor preserves the entered numerical model but does not certify the accuracy of the original physical measurement.

Download & Print

Save the quantity, conventions and complete working

Copy a reusable record

Copy plain text with selected units, every conversion row and exact certificates, or copy generated LaTeX working for a mathematical document. Clipboard failures provide a clear CSV fallback rather than reporting a successful copy.

Download all rows as CSV

The UTF-8 two-column file includes source entry, target choice, precision, factors and exact numerators and denominators. Hidden screen rows and working remain in the export so a compact view does not silently discard the calculation record.

Print or save as PDF

Use Print / Save PDF to open the browser dialog, choose A4 or Letter and review the preview. Editing controls and this guide are excluded. Enable the desired report sections first; extremely long exact records remain complete in CSV.

FAQ

Frequently Asked Questions

How do I convert inches to centimeters or meters?

Select inches as the source and centimeters or meters as the destination, then enter the numerical value. The converter uses a defined meter factor for each unit and divides only after normalizing the source quantity. Its original twelve-inch example gives thirty point four eight centimeters. The report includes the factor route, corresponding meter quantity and a table of other representations, so you can check a result without guessing which direction to multiply.

Can I enter fractions and mixed inch measurements?

Yes. A single value can be a signed decimal, scientific value, fraction such as 3/8, or mixed number such as 2 3/8. Choose inches when that fraction represents inches; the same syntax can represent a fraction of another selected unit. A mixed number requires a proper fractional remainder, and a denominator cannot be zero. The field is a numerical expression with one optional leading sign, not a general arithmetic evaluator.

Does a decimal foot value mean feet and inches?

No. A decimal fraction of a foot is a fraction of the whole foot, not a base-ten inch count. To enter separate feet and inches, choose the compound entry method, supply whole international feet and a remaining nonnegative inch quantity below twelve, and select one sign for the whole value. This makes the intended measurement explicit and avoids interpreting a decimal separator as a unit separator or silently normalizing an ambiguous negative remainder.

Why are international and U.S. survey feet separate?

Their defined meter factors differ slightly, so interchanging them can change a legacy coordinate or long distance. International feet are the ordinary choice for new work in this tool. The survey foot and survey mile are separately labeled historical options for interpreting existing records. The converter changes a unit scale only; it does not transform a geographic coordinate system, identify a survey datum or decide which convention an unlabeled drawing originally used.

How are fractional inches rounded, including negative values?

The optional representation rounds the total absolute inches to the selected subdivision, applies the original sign, and carries a complete inch or foot into the next component. Exact halfway cases go away from zero. The report shows the signed difference between that rounded representation and the exact entered quantity in millimeters. This is separate from significant-figure rounding in the main output, and choosing a coarser subdivision never changes the stored conversion result.

Are points, picas and mils the same as pixels or millimeters?

No. Here a mil is one thousandth of an international inch. A point and a pica use the PostScript and CSS absolute-length conventions stated in the unit list. The pica identifier is not an astronomical parsec. Device pixels, image pixels and historical printing point systems are not interchangeable with these definitions. Use a stated pixel density and the dedicated DPI and PPI calculator when an image needs a separate physical print-size calculation.

Can a converted value be more accurate than my measurement?

An exact conversion factor does not add information to a measured quantity. Displaying more digits can help preserve a numerical calculation, but the uncertainty and resolution of the original instrument still matter. The significant-figure selector controls the report rather than performing an uncertainty analysis. The exact target ratio records the entered number and defined factors; it should not be read as proof that a real object has infinitely precise dimensions.

What do copy, CSV, sharing and printing retain?

Copied text and CSV retain every supported-unit row and exact rational certificates, even when the table or calculation steps are hidden on screen. LaTeX copying provides generated mathematical working. A shared URL restores active inputs, unit choices and report preferences; malformed links leave current inputs unchanged. Printing uses the visible report options and excludes editing controls and the supporting article. Very long exact records remain complete in CSV when compact print space cannot hold every digit.

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About This Tool

About this Length Converter

The Toolarithm Length Converter is a focused measurement tool for representing one entered quantity in a different named length unit. It keeps the original twelve-inch example and seventeen existing metric, international, nautical and print choices, while adding explicitly labeled historical survey and international engineering measures. Every conversion uses the meter as a coherent intermediate unit. Defined factors are retained as reduced rational numbers, so a repeating decimal relationship does not require a rounded intermediate factor. Displayed significant figures remain a presentation choice, and a complete exact numerical certificate is available when the source is a supported decimal or fraction.

The entry method makes common ambiguities visible. A single input accepts decimal, scientific, simple-fraction and mixed-number syntax with a source unit. A separate compound method combines whole international feet and remaining international inches under one sign. The optional fractional-inch representation belongs to the report rather than replacing the stored quantity. Its subdivision, carry behavior and signed millimeter error explain the effect of adopting a coarser ruler reading. Signed values are useful for coordinate differences and displacements; they should not be confused with a negative physical size. Inputs outside the supported syntax or bounds receive validation rather than leaving a stale answer in place.

The result is intended to be inspectable on a phone, copied into a worksheet, shared with another reader or printed as a compact report. Exact certificates and every supported-unit row remain in CSV even when a shorter screen view is selected. The tool is not a general expression evaluator, geographic coordinate transformer, drawing calibration system or uncertainty calculator. Choosing an exact unit definition does not establish measurement resolution, the fit of a manufactured part or the scale of an unlabeled historical record. Those judgments require the original source and its context alongside the numerical conversion.

Editorial Transparency

Who maintains this page

Ownership and review

Written and maintained by the Toolarithm editorial team. No review date is shown without a maintained editorial record. No independent professional review is claimed.

Methodology

Conversion factors are normalized to canonical units and checked in both directions. Exact definitions and offset formulas are preferred over rounded lookup values.

Read the editorial methodology

Dates and sources

Review dates change only after a substantive method or content check.

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