Printable Reference

Length Conversion Chart

Exact lengths. Your reference chart.

Build your chart

Named units. Exact relationships.

Chart type

Reference unit group

Comparison columns

First comparison unit

Second comparison unit

Third comparison unit

Select three different units. Each cell represents the same length as its source row.

View length chart

Precision and working

Chart significant figures

Show exact chart fractionsShow chart calculation steps

Decimal/scientific values support twenty significant digits, eighty characters and written exponents from negative thirty through thirty. Fractions support one hundred digits per component and two hundred forty characters per field. Display digits do not add measurement accuracy.

Chart presets

Your length reference chart

Common reference (original eleven). 11 rows with three comparison columns. Display uses 10 significant figures. Approximation signs identify rounded values; defined relationships remain exact.

Feet and miles use international definitions unless explicitly labeled U.S. survey. Points and picas use PostScript / CSS definitions. This table is a numerical reference, not a calibrated ruler.

Length Conversion Chart — Common reference (original eleven)
Source quantity	Meters	Inches	International feet
Millimeters $1.000000000\,\mathrm{mm}$	$0.001000000000\,\mathrm{m}$	$\approx0.03937007874\,\mathrm{in}$	$\approx0.003280839895\,\mathrm{ft}$
Centimeters $1.000000000\,\mathrm{cm}$	$0.01000000000\,\mathrm{m}$	$\approx0.3937007874\,\mathrm{in}$	$\approx0.03280839895\,\mathrm{ft}$
Meters $1.000000000\,\mathrm{m}$	$1.000000000\,\mathrm{m}$	$\approx39.37007874\,\mathrm{in}$	$\approx3.280839895\,\mathrm{ft}$
Kilometers $1.000000000\,\mathrm{km}$	$1000.000000\,\mathrm{m}$	$\approx39370.07874\,\mathrm{in}$	$\approx3280.839895\,\mathrm{ft}$
Inches $1.000000000\,\mathrm{in}$	$0.02540000000\,\mathrm{m}$	$1.000000000\,\mathrm{in}$	$\approx0.08333333333\,\mathrm{ft}$
International feet $1.000000000\,\mathrm{ft}$	$0.3048000000\,\mathrm{m}$	$12.00000000\,\mathrm{in}$	$1.000000000\,\mathrm{ft}$
International yards $1.000000000\,\mathrm{yd}$	$0.9144000000\,\mathrm{m}$	$36.00000000\,\mathrm{in}$	$3.000000000\,\mathrm{ft}$
International miles $1.000000000\,\mathrm{mi}$	$1609.344000\,\mathrm{m}$	$63360.00000\,\mathrm{in}$	$5280.000000\,\mathrm{ft}$
International nautical miles $1.000000000\,\mathrm{nmi}$	$1852.000000\,\mathrm{m}$	$\approx72913.38583\,\mathrm{in}$	$\approx6076.115486\,\mathrm{ft}$
PostScript / CSS points $1.000000000\,\mathrm{pt}$	$\approx0.0003527777778\,\mathrm{m}$	$\approx0.01388888889\,\mathrm{in}$	$\approx0.001157407407\,\mathrm{ft}$
PostScript / CSS picas $1.000000000\,\mathrm{pc}$	$\approx0.004233333333\,\mathrm{m}$	$\approx0.1666666667\,\mathrm{in}$	$\approx0.01388888889\,\mathrm{ft}$

Step-by-step chart calculation

1. Read the row and column definitions
Each reference row starts with one of its named units. A series uses one source unit and an exact start and increment. International and legacy survey definitions remain separate.
$x=1$
2. Normalize the source through meters
Multiply the source quantity by its exact meter factor. Exact factors describe definitions and do not imply measured accuracy.
$x_{\mathrm m}=x f_{\mathrm{source}},\quad f_{\mathrm{source}}=\frac{1}{1000}$
3. Divide by the comparison-column factor
The first displayed row and first comparison column are worked below. Approximation marks identify display rounding; the remaining cells use the same rule.
$y=x\frac{f_{\mathrm{source}}}{f_{\mathrm{column}}}=0.001000000000\,\mathrm{m}$

What Can You Create?

Create a length reference that matches your task

A focused unit lookup

Keep all eleven original reference units, or focus on metric prefixes, international customary units, nautical distance, typography or historical surveying. The complete reference covers twenty-four explicitly named definitions.

An exact value progression

Generate up to forty equally spaced source quantities, including ordinary fractions, signed offsets and descending rows. Choose three comparison units independently rather than settling for a fixed conversion pair.

A reusable printed reference

Create a readable numerical lookup for a notebook, lesson or layout check. Repeated table headers, explicit unit names and optional working preserve context when the chart continues onto another printed page.

Length chart formulas and worked examples

Convert through exact meter factors

Let $f_s$ and $f_c$ denote the exact meter factors for the source row unit and comparison column unit. Multiply the source number by the first factor and divide by the second. Each row uses its own source definition; each column uses its selected comparison definition. Rounding happens after this ratio is evaluated, so a repeating displayed decimal is not reused as an intermediate conversion factor.

y=x\frac{f_s}{f_c}

Example: a fractional-inch progression

For an eighth-inch start and an eighth-inch increment, the first three quantities are $\frac18\,\mathrm{in}$ , $\frac14\,\mathrm{in}$ and $\frac38\,\mathrm{in}$ . The exact millimeter relationship gives the first value below. The default progression uses sixteen rows, but the row count controls the number of entries rather than a maximum endpoint. If you change the increment, check the final row before saving the chart.

\frac18\,\mathrm{in}=\frac18\cdot25.4\,\mathrm{mm}=3.175\,\mathrm{mm}

Construct a signed arithmetic series

A custom series begins at $a$ and advances by $h$ for each new row. The first index is zero, so a chart of $n$ rows ends at the expression below. A negative increment moves downward and can cross zero. The calculation stores exact rational quantities for every row; display precision does not accumulate an error as the progression grows.

x_i=a+ih,\quad i=0,\ldots,n-1,\qquad x_{\mathrm{last}}=a+(n-1)h

Example: picas and points

PostScript and CSS typography use a fixed relationship between the point, pica and international inch. A pica contains twelve of these points. Selecting both as separate comparison columns makes that ratio visible across every source row. The relationship concerns defined lengths, while actual visible characters depend on a font's design and the device's rendering behavior.

1\,\mathrm{pc}=12\,\mathrm{pt}=\frac16\,\mathrm{in}

Why Users Love This Tool

Understand what every chart cell represents

Definitions stay visible

International feet, historical survey feet and typography conventions have distinct names. A short unit abbreviation does not silently choose another definition.
Source rows and comparison headers state the direction of conversion. Three different column units avoid duplicated comparisons or ambiguous headings.
Approximation signs distinguish rounded decimals from exact relationships. Optional fractions and exported certificates preserve the underlying numerical model.

Keep a record you can check

All generated rows are retained in text and CSV, with source values, target values and the exact factors used. Hiding visible steps does not remove the saved working.
Versioned sharing restores the active chart type, columns and precision after validation. Inactive source controls are excluded from the shared model.
The initial chart and mathematical content render on the server. Keyboard users can focus the scrollable table, and edited results retain accessible mathematical markup.

Perfect For

A chart for lessons, layouts and technical notes

Teachers and learners

Build a sequence with a recognizable increment and compare how the same source quantity is expressed in different systems. Use the first-cell working to explain the general conversion rule before reading the remaining rows.

Design and print preparation

Compare millimeters, international inches, PostScript points and picas with their definitions stated. Numerical equivalence helps inspect specifications; it does not make a screen image or printed table an actual-size measuring tool.

Technical reference preparation

Choose a compact family or all available units, then retain exact factors alongside rounded values. For historical surveying, use a clearly labeled legacy unit only after checking the original source convention.

How It Works

How it works in three quick steps.

Choose a reference group or value series

Keep the original eleven-unit reference or select a named unit family. For a custom series, choose the source unit, signed start, nonzero increment and row count from one through forty.

Select three distinct comparison columns

Choose a different unit for each comparison column, then set display significant figures. Inspect approximation signs, optional exact fractions and working for the first row and first column.

Save the chart with its unit definitions

Copy the complete chart, download exact numerical certificates as CSV, share validated chart settings or print the visible table and working to PDF. Check page size and scaling before printing.

Download & Print

Download and print your selected length reference

Copy or share a reproducible chart

Copy every generated row as readable text, or copy properly delimited LaTeX working. Share chart creates a link containing active settings. A malformed link leaves the current inputs unchanged and provides a clear status message.

Export exact certificates as CSV

Download a quoted UTF-8 file containing each displayed quantity and its exact numerator and denominator in that named unit. It also records the selected scope, series controls where applicable, meter factors and working for independent checking.

Save the visible report as PDF

Use the browser print destination after selecting paper size and scaling. The report removes controls and supporting articles while retaining the chart context, repeated table headings and selected working. Long exact ratios remain fully available in CSV rather than forcing an unreadable table cell.

FAQ

Frequently Asked Questions

How do I read the rows and columns of this length chart?

Start with the source quantity at the left of the row, then move across to the column for your desired unit. Every cell on that row represents the same length. Reference mode starts with one of each named source unit. Series mode starts with the quantity shown in that individual row, so you should not apply another multiplication by its row number.

Are the length conversion chart values exact?

The unit factors use exact defined relationships, including

1\,\mathrm{in}=25.4\,\mathrm{mm}

. The displayed decimal may still need rounding, particularly for a recurring expansion. An approximation sign identifies that rounding. Optional second lines show compact exact fractions, while complete numerator and denominator certificates are saved in text and CSV. Neither extra decimal places nor an exact factor can improve the accuracy of an original measured length.

Can I make a fractional-inch to millimeter lookup chart?

Yes. Load the Fractional-inch lookup preset to generate sixteen rows using an eighth-inch start and increment. You can then edit the start, increment, source unit and row count, and select millimeters as any comparison column. Enter ordinary fractions or proper mixed numbers in the controls. The progression is generated using exact rational arithmetic rather than repeated rounded decimal additions.

How are international feet and U.S. survey feet handled?

The chart explicitly distinguishes international feet from historical U.S. survey feet. The international relationship is

1\,\mathrm{ft}=0.3048\,\mathrm m

; the legacy survey factor is

1200/3937

meters per survey foot. Use the named legacy group only when the original dataset specifies it. Selecting a unit changes a numerical length representation; it does not transform coordinates, change a map datum or infer which survey convention a document intended.

Which point and pica definitions does the chart use?

Typography choices use the PostScript and CSS definitions:

1\,\mathrm{pt}=\frac{1}{72}\,\mathrm{in}

and

1\,\mathrm{pc}=\frac{1}{6}\,\mathrm{in}

. Other historical point systems need their own definitions and should not be assumed equivalent. A font's point size also does not guarantee its visible letter height. This chart compares defined lengths; it does not measure glyph shapes, screen pixels, image resolution or device-specific rendering.

Can my series include negative values or count downward?

Yes. A series may start above or below zero, and a negative increment produces descending rows. A nonzero increment and a whole row count from one through forty are required. Negative lengths here are signed mathematical quantities, useful for offsets or coordinate differences; they are not claims that a physical object has a negative size. Invalid or incomplete edits remove stale chart results until corrected.

What is included in copied text, CSV and shared chart links?

Copied text and CSV include every generated source quantity, its three comparison values, exact rational certificates, the relevant meter factors and working. The CSV remains complete when visible steps are hidden. A share link instead stores validated active chart settings and regenerates the chart when opened. Inactive series buffers do not travel with a reference chart, and hidden group choices do not travel with a custom series.

Can I print this length chart as an actual-size ruler?

The chart is a numerical lookup reference, so its printed dimensions do not represent the lengths in its cells. Use Print / Save PDF to retain the visible table and selected working. Confirm the destination, paper size, orientation and scale in the browser preview. Repeated table headers help identify continued pages. For actual-size measuring marks, use a calibrated ruler or a purpose-built printable scale and independently verify the physical output.

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About This Tool

About this Length Conversion Chart

The Toolarithm Length Conversion Chart is a configurable numerical reference for comparing defined lengths. It keeps the original eleven common rows while allowing a focused unit family or all twenty-four available definitions. Every reference row begins with one source unit, and three independently selected columns show the same length in other conventions. This arrangement makes conversion direction explicit instead of mixing unlabeled metric and customary reference values in a fixed list.

Custom series mode serves a different lookup need: a progression in one chosen source unit. A signed start, nonzero increment and bounded row count generate equally spaced entries without repeatedly adding rounded display values. Ordinary fractions and proper mixed numbers work alongside decimal and scientific input. A negative increment can cross zero, making the chart useful for mathematical offsets as well as positive measurement references. Each edit is validated before a new result is presented, so incomplete inputs do not leave an old chart appearing current.

The unit catalog separates international customary units, nautical distance, PostScript and CSS typography, and historical U.S. survey conventions. Factors are stored as exact rational meter relationships. Optional compact fractions and complete exported numerical certificates describe that calculation model; they do not certify a measuring instrument, a document specification or the precision of a physical observation. The chart does not perform a coordinate-reference transformation, infer a historical surveying convention, measure glyph height or establish image resolution.

Server-rendered defaults remain available before interactive code loads. Mathematical content is typeset with accessible LaTeX and MathML, while source-entry syntax stays literal in form controls. Text and CSV retain every generated row, relevant exact factors and working, including steps hidden in the visible report. Print mode keeps the selected chart and its context while removing controls and unrelated content. It produces a numerical reference for reading and checking, rather than a physical ruler whose spacing could be trusted without calibration.

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

The editorial team checks definitions, examples, linked tools, and cited references. Dates shown here come from the page's maintained publication record.

Read the editorial methodology

Dates and sources

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

Length conversion diagram showing exact inch, international mile, and nautical mile relationships. — Three exact length anchors for metric, imperial, nautical, and print-reference conversions.

Defined factors and measured values

Choose the factor first, then round the result

A conversion factor can be exact even when the measured quantity is not. This chart distinguishes defined metric-customary relationships from convenient decimal displays so a lookup does not imply more accuracy than the original measurement supports.

Anchor relationships used by this chart

These factors connect the metric, international customary, nautical, and print units represented in the table.

International inch: $1\,\mathrm{in}=25.4\,\mathrm{mm}$ exactly.
International foot: $12\,\mathrm{in}=0.3048\,\mathrm{m}$ exactly.
International mile: $5280\,\mathrm{ft}=1609.344\,\mathrm{m}$ exactly, using international feet.
Nautical mile: $1\,\mathrm{nmi}=1852\,\mathrm{m}$ exactly.
PostScript point: $1\,\mathrm{pt}=\frac{1}{72}\,\mathrm{in}$ .
Pica: $1\,\mathrm{pc}=12\,\mathrm{pt}=\frac{1}{6}\,\mathrm{in}$ .

Exact definitions do not create measurement precision

Twelve inches converts to exactly 304.8 millimeters because the inch factor is defined exactly. If the original length was recorded only as 12 inches to the nearest inch, however, 304.8 millimeters should not be interpreted as a sub-millimeter measurement.

Carry sufficient digits through the multiplication, then round the final answer to a precision appropriate for the source value and task. Avoid rounding the factor before the calculation when an exact defined relationship is available.

Keep reference-chart and live-converter jobs separate

The chart is optimized for one-unit anchors and print lookup. It makes relationships such as an inch to millimeters or a point to an inch easy to scan and copy.

Open the live length converter for arbitrary source values, scientific notation, or comparison across the full supported unit set. That avoids mentally scaling a one-unit row when the input is large, small, or fractional.

Identify the foot before using legacy records

This page uses the international foot. It does not substitute the former U.S. survey foot that appears in some historic land-survey and geospatial records.

When a source dataset names a different realization of a unit, preserve that definition through the calculation. A modern international-foot chart should not silently relabel legacy coordinates or boundary measurements.

Worked check: convert one foot to millimeters

1Start with $1\,\mathrm{ft}=12\,\mathrm{in}$ .
2Apply the exact factor 25.4 millimeters per inch: $12\times25.4=304.8$ .
3Report 304.8 millimeters as the defined equivalent, then apply task-appropriate rounding only if the source measurement itself was approximate.

Copying and printing guidance

Decimal factors in the table are formatted for readable reference. Copy the exact definition when one is listed, especially for chains of calculations.
Typography points here follow the 72-points-per-inch print convention. Other historical point systems are outside the chart's scope.
The four-column table owns its horizontal scrolling on a phone. For paper, landscape orientation usually retains the note column more legibly than fit-to-page shrinking.

Sources and definitions

NIST SP 811, Appendix B: conversion factors
Primary U.S. metrology reference for SI and customary conversion relationships.

Continue the task

Related next steps

Live length converterConvert an arbitrary value across all supported length units.Paper size converterApply length units to finished sheet dimensions.Common unit guideReview factor selection and dimensional checks.

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