Convert ft to in feet ↔ inches Free Online Secure
Type a value in feet and read it in inches at once. The factor is exact by definition, the arithmetic happens in your browser, and nothing is sent anywhere.
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Common values — Convert ft to in (feet ↔ inches)
| ft | in |
|---|---|
| 1 | 12 |
| 2 | 24 |
| 3 | 36 |
| 5 | 60 |
| 10 | 120 |
| 20 | 240 |
| 50 | 600 |
| 100 | 1200 |
Where these units come from
The metre was first defined in 1793 as a ten-millionth of the distance from the equator to the North Pole — a definition nobody could check without surveying a quarter of the planet. It has been redefined four times since, each time to something steadier: a platinum bar, then a prototype kept in Paris, then a wavelength of krypton light, and since 1983 the distance light travels in vacuum in 1/299,792,458 of a second. The inch stopped being a separate thing in 1959, when six countries agreed to define it as exactly 25.4 mm. That agreement is why every conversion on this page between a metric and an imperial length is exact rather than measured: both sides now descend from the same definition.
Where you meet them
Millimetres are the working unit of engineering drawings and of anything made in a workshop; centimetres belong to tailoring, furniture and school rulers; metres to rooms, fabric and running tracks. Feet and inches survive in aviation altitudes worldwide, in American and British construction, and in the diagonal of every screen you have ever bought. Nautical miles are not a quaint survival — one is a minute of latitude, which is why ships and aircraft still navigate in them.
Questions people ask
Why are aircraft altitudes given in feet?
Because international aviation standardised on feet decades ago and has never had a reason to change. Flight levels are altitudes in hundreds of feet, so level 350 is 35,000 feet. A foot is exactly 0.3048 metres, so converting is exact; a few countries, such as China and Russia, have used metres instead, which is why pilots must know both.
Why is 1 inch exactly 25.4 mm?
Because in 1959 the standards bodies of the United States, the United Kingdom, Canada, Australia, New Zealand and South Africa agreed to make it so. Before that the American inch and the British inch differed in the seventh decimal place, which was enough to matter when parts made on one side of the Atlantic had to fit parts made on the other. The agreed value is a definition, not a measurement, so it will not be revised.
Is the answer exact?
Where both units are defined in terms of one another by whole numbers, yes — the page says so above the figure, and the only rounding is in how many digits are shown. Where the ratio has no finite decimal, the page shows twelve significant digits and says the relation is approximate rather than pretending otherwise.
Does anything I type leave my device?
No. The arithmetic runs in your browser; nothing is uploaded and there is no server to upload it to. Load the page once and it keeps working with the network switched off.
Twelve to the foot: a quick way to convert ft to in
Few conversions are as common in an American workshop, a British hardware shop or a home-improvement video as the one between feet and inches. A board is cut to six feet, but the saw guide is marked in inches; a rug is advertised as nine by twelve feet, while the room plan you downloaded lists everything in inches. To compare the two on a single scale you have to convert ft to in, and this page does it the moment you type a number: enter a length in feet and read it in inches.
Both units of this “convert ft to in” calculation belong to the same imperial family, so no awkward constant is involved. A foot is exactly twelve inches, and that is the whole story of the arithmetic. The challenge is rather in the habits around it, because lengths are often written as mixed feet and inches, and fractions of an inch pile up quickly. The sections that follow set out the rule, give worked examples, introduce each unit, compare them, list where the conversion matters and warn about the usual slips.
How to convert ft to in: multiply by twelve
The rule
One foot contains twelve inches, so to convert ft to in you multiply the number of feet by 12. Two feet are 24 inches, five feet are 60 inches, ten feet are 120 inches. A decimal number works the same way: 2.5 ft is 30 in, 0.75 ft is 9 in, and 6.25 ft is 75 in. The result is exact, with no rounding, since the relation between the two units is defined by whole numbers.
Examples from the shop
A 4 ft by 8 ft sheet of plywood is 48 by 96 in. An 8 ft stud is 96 in. A 6 ft fence picket is 72 in. A 15 ft garden hose coil is 180 in. Each answer is simply the number of feet times twelve, whether you do it with pencil, calculator or in your head.
Doing it in your head
Multiply by ten and add twice the original number. For 7 ft: 70 plus 14 is 84 in. For 13 ft: 130 plus 26 is 156 in. This split into ten and two is easier than multiplying by twelve directly, and it is what many carpenters do without noticing.
Fractions of a foot
A quarter of a foot is 3 in, a third is 4 in, a half is 6 in and two thirds is 8 in. Learning these four lets you convert most everyday fractions at a glance.
The foot
A unit with a long history
The foot goes back to antiquity, when it was the length of a human foot or a standard bar kept by the authorities. Egyptian, Greek, Roman and medieval foot measures differed by a few centimetres. Modern usage dates from 1959, when English-speaking countries agreed to define the international foot as exactly 0.3048 metres.
Where it lives today
The foot is used in the United States for construction, real estate, sports fields and body height, and in Britain for height and some building trades. Aviation uses it for altitude all over the world. Its symbol is ft, or a single prime mark written after the number.
The inch
One twelfth of a foot
An inch is one twelfth of a foot and, since 1959, exactly 25.4 millimetres. The word comes from the Latin for a twelfth part, which is also the origin of the word ounce. Medieval kings defined the inch by the width of a thumb or by three grains of barley placed end to end, a custom you can find in old legal texts.
Its modern forms
The symbol is in, or a double prime. Inches are divided in halves, quarters, eighths and sixteenths on tape measures, and in thousandths of an inch, called mils or thou, in machining. Screen sizes, tyre diameters and pipe sizes all use inches nearly everywhere in the world.
Feet and inches compared
Twelve inches make one foot, and three feet make a yard. This duodecimal structure suits halving, thirding and quartering without leftovers, which is why builders have preferred it for centuries. A decimal system cannot split a unit by three without a repeating fraction.
For short lengths, inches are more natural: a pencil is 7 in, a phone 6 in. For room and board sizes, feet are more convenient: a room 12 ft wide is easier to say than 144 in. Mixed forms such as 5 ft 9 in are the ordinary way to give a person height. When you write for a general public, choose the unit people use for that object and keep it throughout.
Where you will need it
Carpentry and framing
Before any convert ft to in for a wall, note that studs are set 16 in apart, centre to centre, so a 12 ft wall needs 144 divided by 16, nine bays and ten studs counting the ends. A 10 ft board is 120 in, enough for exactly seven 16 in cuts with 8 in left over. Working in inches avoids the error that comes from mixing feet and fractions.
Mattresses and furniture
A queen mattress measures 60 by 80 in, which is 5 by 6.67 ft. A king mattress is 76 by 80 in, or 6.33 by 6.67 ft. Knowing the size in both units helps you test whether it will fit through a door 3 ft, or 36 in, wide.
Screens and frames
Televisions are named for the diagonal in inches: a 55 in set is 4.58 ft across the diagonal. Picture frames come in 8 by 10, 11 by 14 and 16 by 20 in. If a wall is 9 ft wide, 108 in, you can calculate how many frames fit side by side with gaps of 2 in.
Pipes, rope and cable
Cable and pipe are bought by the foot but fitted by the inch. A 25 ft extension cord is 300 in, enough to cross a room of 20 ft with 5 ft to spare. Plumbers convert both ways all day.
Height and body measurements
Five foot nine
People say their height as 5 ft 9 in, which is 69 in. Doctors and clothing tables then use the inch number. The conversion is 5 times 12 plus 9, which gives 69. A person of 6 ft 2 in is 74 in, and a child of 4 ft 3 in is 51 in.
Clothing sizes
Trouser inseams run from 28 to 36 in, shirt sleeves from 32 to 37 in. A tailor who gives a sleeve length in feet, such as 2.75 ft, expects you to convert ft to in and get 33 in. A tape measure with inches only on one edge makes the mental step unnecessary.
Quality checks
Is the number twelve times larger?
If your “convert ft to in” calculation result is not twelve times the feet figure, something is wrong. A quick test: divide the inches by 12 and compare with the starting value.
Cross-check with metric
Feet to metres is a factor of 0.3048, inches to centimetres 2.54. Check that 10 ft, 3.048 m, and 120 in, 304.8 cm, agree. It takes seconds and settles the matter.
A short history of the inch
Barleycorns and thumbs
In 1324 an English statute defined the inch as three barleycorns, round and dry, laid end to end. Earlier, the inch was the width of a man's thumb at the base of the nail. Kings kept brass bars in the palace as reference.
The decision of 1959
With the international agreement of 1959 the inch was fixed at 25.4 mm, and with it the foot at 12 in. Nothing about the relation between the two units has changed since the Middle Ages, only the length of the unit itself.
Teaching the twelve times table
With a ruler
A 12 in ruler is the best classroom tool: one foot, twelve inches. Have students lay several end to end and count the inches, which builds the twelve times table naturally.
A game for pairs
One student gives a length in feet, the other answers in inches, and the pair checks with a tape. Students quickly notice patterns such as multiples of six being half feet.
A worked project: building a bookshelf
From the plan to the saw
Suppose a plan calls for a bookshelf 6 ft high and 3 ft wide, with five shelves. The first step is to convert ft to in on every dimension: the sides are 72 in, the shelves 36 in less the thickness of the two sides, say 34.5 in. Five shelves at 34.5 in need 172.5 in of board, which is 14 ft 4.5 in, so a pair of 8 ft boards, 192 in, will do with 19.5 in left for a back brace.
Why inches help here
With the numbers in inches, subtracting the thickness of the boards is a simple operation, and the offcuts can be added up without fractions of a foot. Once everything is cut, you can return to feet to describe the finished piece to a friend.
Keeping a conversion card
The four anchors
Pin four numbers above your bench: 1 ft is 12 in, 2 ft is 24 in, 4 ft is 48 in, 8 ft is 96 in. These are the sizes of sheets and studs and they cover most everyday jobs. Everything else is addition, because 6 ft is 48 plus 24 and 7 ft is 96 minus 12. With this card nobody needs to convert ft to in on a calculator for common lengths.
Share it
If you work with others, put the card on the wall of the shop. Apprentices learn the numbers by sight, and arguments about what the plan meant happen less often.
Real estate and room sizes
Floor plans
Listings give rooms as 12 by 14 ft, which is 144 by 168 in. The area is 168 square feet, or 24,192 square inches. If you design a layout in a program that uses inches, convert first, then place the furniture to scale.
Ceiling and door heights
Standard doors are 80 in high, or 6 ft 8 in, and ceilings 8 ft, or 96 in. A clearance of 16 in above the door frame sounds small until you realise it holds the header and drywall.
Sports and playing fields
Courts and nets
A basketball rim hangs at 10 ft, or 120 in. A tennis net is 36 in at the posts, 3 ft. A volleyball net for men is 7 ft 11 5/8 in, which is 95.625 in. A hockey goal is 6 ft by 4 ft, or 72 by 48 in. Coaches switch between feet for the layout and inches for the equipment.
Golf and archery
A golf club length is given in inches, usually 45 for a driver, which is 3.75 ft. A longbow is often 66 to 72 in, 5.5 to 6 ft. For these items the feet figure gives a feel and the inch figure gives the number to buy.
Tyres and wheels
Diameters in inches
Car wheels are specified in inches, 15 to 20 in, so a 16 in wheel is 1.33 ft across. A bicycle wheel at 26 in is 2.17 ft. Tractor tyres reach 6 ft, or 72 in, in diameter. To convert ft to in for scale gives a sense of size, converting to inches gives the figure that determines fit.
Ground clearance
An SUV with 9 in clearance is 0.75 ft off the ground. A tractor with 24 in clearance is 2 ft. Heights of obstacles are given in feet, so you convert the vehicle figure to compare.
Aircraft and ships
Lengths on spec sheets
A small aircraft can have a wingspan of 36 ft, which is 432 in. A boat of 24 ft is 288 in. Shipping documents often list only the foot length, while repair manuals use inches for parts. Converting between them is a routine task for mechanics.
Altitude and depth
Altitude uses feet, but equipment clearances at airports use inches. A hangar door 22 ft high is 264 in. Water depth for boats is given in feet, and the draft of a small sailboat in feet and inches, such as 4 ft 6 in, which is 54 in.
Gardening and landscaping
Spacing plants
Seed packets give spacing in inches: tomatoes 24 in, lettuce 8 in, carrots 2 in. A bed 12 ft long, 144 in, holds six tomato plants spaced 24 in apart, or eighteen lettuces at 8 in. Feet for the bed, inches for the plants.
Mulch and edging
A 3 in layer of mulch over a bed 10 by 4 ft, 120 by 48 in, uses 10 cubic feet. That is a convenient way to order by the bag. Edging comes in 10 ft lengths, 120 in, so a perimeter of 28 ft needs three lengths.
Sewing and crafts
Fabric
Fabric is sold by the yard, 36 in, and by the foot at some stores. A pillow cover needs 18 in squares, so a 3 ft length gives two panels. A curtain 7 ft long, 84 in, needs 2.33 yards.
Patterns
Seam allowances are 5/8 in. A skirt of 2 ft is 24 in long. When you convert ft to in, include the hem allowance as well, usually 2 in.
Mixed numbers
Feet, inches and fractions
A length such as 3 ft 4 1/2 in becomes 36 plus 4.5, which is 40.5 in. A drawing may list 5 ft 3 3/4 in, which is 63.75 in. To go back, divide by 12 and keep the remainder: 63.75 divided by 12 is 5 with 3.75 left over.
Tape measure reading
The marks on a tape are halves, quarters, eighths and sixteenths. Counting sixteenths from the nearest inch is easy once you see that 8 sixteenths is a half, 4 a quarter, and 2 an eighth.
Working with larger numbers
Long runs
A fence of 250 ft is 3,000 in. A road of 5,280 ft, one mile, is 63,360 in. At this scale, inches produce long numbers that are harder to read than feet, so only convert when a calculation requires it.
Thousands separators
Use commas or thin spaces consistently so that 63,360 is not mistaken for 6,336. A pasted spreadsheet can strip separators, so check the cell format before you trust the result.
More values for convert ft to in
A longer list of conversions
If the value you need is not in the first list, these further conversions may be close enough to read off directly:
- 0.1 ft = 1.2 in
- 0.5 ft = 6 in
- 3 ft = 36 in
- 4 ft = 48 in
- 7 ft = 84 in
- 15 ft = 180 in
- 20 ft = 240 in
- 75 ft = 900 in
- 200 ft = 2,400 in
- 500 ft = 6,000 in
- 2,000 ft = 24,000 in
- 10,000 ft = 120,000 in
Mistakes when you convert ft to in
Multiplying by ten
Twelve, not ten. Decimal habits sneak in, and 8 ft becomes 80 in instead of 96.
Mixing mixed numbers
5 ft 9 in is not 5.9 ft. Convert the feet first and add the inches: 60 plus 9 is 69.
Forgetting the unit
Always write ft or in beside the number. A bare 72 could be inches or feet.
Quick answers
How many inches in a foot?
Twelve.
How do I convert ft to in?
Multiply the number of feet by twelve.
What is 6.5 ft in inches?
78 in.
Is the conversion exact?
Yes, it is exact.
Does my number leave my device?
No. The calculation runs in your browser.
Related pages and a last word
If you work with lengths, these conversions are close at hand: Convert ft to m, Convert ft to mi, Convert dm to in, Convert mm to in, Convert in to dm, Convert °C to °F, Convert °F to °C, Convert L to gal, Convert gal to L. The reverse of this page is Convert in to ft.
In short, to convert ft to in multiply by twelve, split mixed numbers into feet and inches before you start, and keep only the digits your measurement supports. Your number stays on your device: nothing is uploaded and no account is needed.