Length Converter
The Length Converter instantly converts between metric and imperial length units, including millimeters, centimeters, meters, kilometers, inches, feet, yards, and miles. It's commonly used for tasks like converting furniture or room dimensions from a US retailer's inches to metric ahead of an international move, or checking a recipe or DIY project's measurements against a tape measure marked in the other system. Conversion factors are fixed, internationally defined constants, so results are exact aside from standard decimal rounding in the display.
How This Tool Works
Enter a value and choose your source and target length units for an instant conversion.
Formula & Method
All units convert through meters as a common base, e.g., 1 foot = 0.3048 meters, 1 inch = 0.0254 meters.
Example Calculation
6 feet converts to about 1.83 meters, or 72 inches. A 10-kilometer race distance converts to about 6.21 miles, or roughly 32,808 feet — handy for comparing race distances listed in different countries. A 5K comes out to about 3.11 miles, just over the "5K = 3 miles" rule of thumb runners often use.
About the Length Converter
Length is the measurement most people meet in both systems at the same time. A bookshelf is listed in inches, the room it goes into was drawn in meters, a hardware-store tape is marked in feet and sixteenths, and the instructions for the bracket are in millimeters. This converter handles eight units, millimeters, centimeters, meters, kilometers, inches, feet, yards and miles, and moves a number from any one to any other in a single step, so you can work in the unit your materials and tools are marked in.
Every conversion passes through the meter. The inch is defined as exactly 0.0254 meters, the foot as 0.3048, the yard as 0.9144 and the mile as 1,609.344, and the metric units are simple powers of ten. Because those figures are definitions rather than measured values, the conversion adds no error of its own. What you see is limited only by display rounding, which cuts the answer off at six decimal places, a resolution far finer than any tape measure can read.
People use the tool for furniture and appliance fit checks, for cutting lumber and fabric, for reading product dimensions from overseas listings, for school and lab work, and for comparing distances like race lengths. It converts a single value at a time, so a measurement written as feet and inches, or as a fraction, needs a small preparation step first. The how-to steps and tips below show how to turn those everyday formats into a clean decimal before converting.
When to Use It
Checking whether furniture fits
Someone buying a sofa from a US store sees a width of 84 inches and has a gap in the living room measured at 2.1 meters with a metric tape. They convert one measurement into the other's unit, leave room for the doorway and delivery path, and decide whether the sofa is worth ordering.
Working from a metric plan
A woodworker in the US downloads a plan with parts listed in millimeters, but her tape and saw fence are in inches. She converts each cut length, rounds to the nearest sixteenth she can actually mark, and writes the imperial lengths on the board before touching the saw.
Reading a height or size chart
A parent shopping online for a child's bike finds that the frame guide gives rider heights in centimeters while the child was measured in feet and inches at the doctor. Converting once gives a figure to compare with the chart and avoids buying the wrong size.
Comparing track and road distances
A coach planning a workout for a mixed group has a 400-meter track and runners who think in miles. Converting kilometers, yards or miles to meters lets him set lap counts for each person without guessing at the rounding.
How to Use It, Step by Step
- Decide which single number you are converting. If your measurement is written as feet and inches, such as 5 ft 11 in, first change it to one unit by multiplying the feet by 12 and adding the inches, giving 71 inches.
- Turn any fraction into a decimal before typing. For example, 3/8 of an inch is 0.375 and 5/8 is 0.625, so a board length of 36 and 5/8 inches is entered as 36.625 in the Value field.
- Type the number into the Value field. It accepts zero or larger values up to one billion and decimals, so you can enter 0.5 or 12.75 without trouble.
- Pick the unit you started with in the From list, choosing from Millimeters, Centimeters, Meters, Kilometers, Inches, Feet, Yards or Miles. The page opens with Feet selected as the starting unit.
- Pick the unit you want in the To list. It starts on Meters; for a result in inches, centimeters or millimeters, change it before converting so you do not read the wrong unit.
- Press the Convert Length button and read the summary line, which restates your value and the converted figure. The highlighted In box beneath shows the same answer with the name of the target unit.
- Round the result to something you can mark. A tape measure resolves about a millimeter or a sixteenth of an inch, so a six-decimal answer should be rounded to that scale before you cut, drill or order.
- For a measurement in two parts, such as a result in meters you want as feet and inches, convert to inches first, divide by 12 for the whole feet and keep the remainder as inches.
Understanding Your Results
The summary line shows your input and the answer in the chosen units, for example 71 inches = 180.34 centimeters. Values with thousands get commas, and anything beyond six decimal places is trimmed. A whole-number answer, such as 1,760 yards in a mile, means the two units divide evenly; a long decimal like 8.005249 means they do not, and you should round it to the precision your task needs.
A good sanity check is to compare sizes. There are 25.4 millimeters in an inch, about 3.28 feet in a meter and 1.0936 yards in a meter, so your answer should have a number larger than the input when you go from a big unit to a small one, and smaller when you go the other way. If a result goes the wrong direction, the From and To lists are probably swapped.
Decide what to do with the answer before you use it. For cuts, round to the smallest division you can mark and note whether to round up or down: round up for clearance holes, down for items that must fit inside something. For purchases, check that the product's own listed dimensions agree with the converted number, since manufacturers sometimes round them differently.
More Worked Examples
A 5 ft 11 in height in centimeters
Scenario: Value 71, From Inches, To Centimeters.
First convert 5 feet 11 inches to a single unit: 5 times 12 is 60, plus 11 is 71 inches. Entering 71 with Inches as the From unit and Centimeters as the To unit returns 180.34 centimeters. This is exact, since one inch is defined as 2.54 centimeters and 71 times 2.54 is 180.34. A size chart that lists 180 cm therefore fits this person with a third of a centimeter to spare.
A sheet of plywood in feet and inches
Scenario: Value 2440, From Millimeters, To Feet, then To Inches.
Sheet goods in metric countries are commonly sold at 2,440 millimeters long. With Millimeters as the source and Feet as the target, the tool returns 8.005249 feet; switching the target to Inches returns 96.062992 inches. A US 8-foot sheet is 96 inches, so the metric sheet is about 0.06 inch longer. For a cut list that is close enough to treat as 8 feet, but a snug fit between fixed points is another matter.
Baseball base paths in meters
Scenario: Value 90, From Feet, To Meters.
The bases on a standard baseball diamond are 90 feet apart. With Feet as the From unit and Meters as the To unit, the tool multiplies 90 by 0.3048 and returns 27.432 meters. Four such legs make a full circuit of 109.728 meters, which a coach can set up on a metric field using a 30-meter tape. The conversion is exact, so any difference on the field comes from marking, not from the arithmetic.
Tips for Better Results
- Memorize two exact anchors, 1 inch is 2.54 centimeters and 1 foot is 0.3048 meters. With those you can check any single conversion in your head and spot a typo in either list.
- Convert once, then work in the new unit. Switching back and forth between systems during a project multiplies chances for slips, so decide which unit your tools use and keep everything in it.
- When cutting, add the kerf of the saw blade to your cut plan and convert the final number, not each piece separately. Small rounding errors on many pieces can add up to a gap of several millimeters.
- Keep decimal inches for the tool and fractions for the tape. To go from decimals to fractions, multiply the decimal part by 16 and round: 0.375 times 16 is 6, so 6/16 or 3/8 of an inch.
- For long distances, convert kilometers and miles directly rather than going through meters by hand. The tool shows six decimals, which is enough that rounding the result to two decimals is usually safe for travel plans.
- If you shop across borders, check whether a listing's dimensions are nominal. A lumber size labeled 2 by 4 inches is actually smaller, so converting the label gives a number that does not match the physical board.
Common Mistakes to Avoid
- Typing feet and inches as one decimal. 5.11 feet is not 5 feet 11 inches, because 11 inches is 0.9167 foot; convert the whole length to inches first and enter 71.
- Entering a fraction as a decimal incorrectly. A measurement of 3 and 1/8 inches is 3.125, not 3.18, so divide the fraction before typing it into the Value field.
- Leaving the default units without looking. The page starts on Feet to Meters, so a value meant as centimeters will quietly be read as feet if you forget to change the From list.
- Squaring or cubing the length result by hand. For floors, fabric or volumes, convert the dimensions to the same unit and then calculate, or use the area and volume tools, because converting the area by the linear factor is wrong.
- Trusting more precision than the measurement has. A length measured to the nearest quarter inch does not become exact because the converter shows six decimals, so round the answer back to the precision of the original reading.
Assumptions and Limits
- Every factor in the tool is an exact definition: the inch is 2.54 centimeters, the foot 0.3048 meters, the yard 0.9144 meters and the mile 1,609.344 meters. The international inch and foot are used, not the older US survey foot, which differs by about two parts per million and matters only in large land surveys.
- The answer is rounded to a maximum of six decimal places for display. For ordinary lengths that is more precision than needed, but for very large unit differences, such as millimeters to miles, the leading digits can be zeros and you may prefer a different target unit.
- The tool converts a single length value. It does not combine mixed units such as feet plus inches, and it does not understand fractions, so you need to prepare the number before typing it.
- For engineering drawings, legal property descriptions or anything with tolerances, use the units and rounding rules in the governing document or consult the engineer or surveyor responsible for the work.
Key Terms
- Metric prefix
- A word part such as milli, centi or kilo that multiplies a base unit by a power of ten: a millimeter is one thousandth of a meter and a kilometer is one thousand meters.
- International inch
- The inch as fixed by the 1959 international yard and pound agreement at exactly 25.4 millimeters. It is the inch used in this converter and in most modern standards.
- Base unit
- The unit a converter routes every value through. Here it is the meter, so converting inches to miles is done by going inches to meters to miles.
- Kerf
- The thin strip of material removed by a saw blade. It is why pieces cut from a board add up to slightly less than the board's full length.
- Tolerance
- The permitted variation from a target size, such as plus or minus half a millimeter. Rounding a converted length should stay well inside the tolerance of the job.
- Nominal size
- A name for a product's size that differs from its true dimensions, like a two-by-four board which is smaller than two inches by four inches after milling.
Related guides
Frequently Asked Questions
How many centimeters are in an inch?+
One inch equals exactly 2.54 centimeters.
How many feet are in a meter?+
One meter equals approximately 3.281 feet.
Is this converter precise enough for construction?+
Yes, conversions use standard, internationally recognized conversion factors accurate to several decimal places.
Can I convert nautical miles or other specialized length units?+
This converter covers the most commonly used metric and imperial units, from millimeters through miles. For less common units like nautical miles (1 nautical mile = 1.852 km) or fathoms, you'd need a specialized converter, though you can still use meters or kilometers here as an intermediate step.
Why do some other sites give a slightly different conversion result?+
Small discrepancies usually come from rounding — some tools round intermediate values or use approximate factors, like treating 1 mile as 1.6 km instead of the exact 1.609344 km. This calculator uses precise, standard conversion factors throughout, so results match official definitions to several decimal places.
How do I convert feet and inches to centimeters?+
Change the whole measurement to inches first, then convert. Multiply the feet by 12, add the inches, enter the total with Inches as the From unit and Centimeters as the To unit. For 6 feet 2 inches that is 74 inches, which the tool turns into 187.96 centimeters. Entering the feet and inches separately and adding afterwards also works, but the single-number method has fewer steps.
Why is an inch exactly 2.54 centimeters?+
Before 1959 the United States, United Kingdom and other countries used slightly different inches, differing in the sixth or seventh digit. In that year they agreed on the international yard of exactly 0.9144 meters, which makes one inch exactly 25.4 millimeters. Since then the conversion has not changed, so the value in this tool is a definition and not a rounded approximation.
How do I convert fractions like 5/8 inch?+
Divide the top number by the bottom number to get a decimal, then enter the decimal in the Value field. Five eighths is 0.625 inch, which converts to 15.875 millimeters. For a mixed number such as 2 and 3/16 inches, divide 3 by 16 to get 0.1875, add 2, and type 2.1875. The tool does not accept fractions typed with a slash.
Can I use this to convert area or volume?+
Not directly. Area scales with the square of the length factor and volume with the cube, so converting a length result by the linear factor gives the wrong answer. Convert each side to the same unit first and then calculate the area, or use the dedicated area and volume converters. Entering 10 feet as 3.048 meters and multiplying sides in meters is correct; multiplying an area in square feet by 0.3048 is not.
What is the difference between the US survey foot and the international foot?+
The US survey foot was used in land surveying and is longer than the international foot by about two parts per million, about 0.01 foot per mile. U.S. agencies retired it at the end of 2022 in favor of the international foot. This converter uses the international foot of exactly 0.3048 meters, which is the right choice for everyday measurement.
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<a href="https://everyfix.net/tools/length-converter/">Length Converter</a> by <a href="https://everyfix.net">EveryFix</a>Related Tools
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