Enter a height in any common unit — feet and inches, centimeters, meters, millimeters, or decimal inches — and this free calculator instantly converts it to total inches with the nearest construction-grade fraction (1⁄16 inch precision). The conversion uses the exact international yard-pound agreement: 1 inch = 2.54 cm by definition. Useful for construction, drafting, anatomy, sports, and any task where you need to translate between imperial and metric height measurements.
Converting a height to inches is a common task wherever the imperial and metric systems meet. In the United States, Canada (informally), the United Kingdom, and a few other countries, personal heights are commonly given in feet and inches: '5 foot 10' is shorthand for 5 ft 10 in (70 inches). Construction in those countries also uses inches and fractions of inches: a 2×4 lumber piece is nominally 1.5 in × 3.5 in actual; standard interior doors are 80 in tall; residential ceilings are 96 in (8 ft) high. Outside those countries, heights are given in centimeters or meters: 178 cm or 1.78 m for that same 5'10" person. The conversion factor is exact: 1 inch = 2.54 centimeters by definition (1959 international yard-pound agreement). Converting between systems matters when you're importing materials, working from drawings in a different unit system, comparing athletes' heights internationally, or just figuring out what '180 cm' means in feet. This calculator handles all the standard direction: feet+inches → inches, cm → inches, m → inches, mm → inches, and the reverse — total inches → all units, with the nearest construction-grade fractional inch (1⁄16 in precision) for ready-to-cut measurements.
The math is straightforward — three constants do all the work. Understanding where each one comes from helps you avoid the most common rounding mistakes.
The foot has been divided into 12 inches since medieval English measurement standards. Twelve was chosen because it has many divisors (2, 3, 4, 6), making mental fraction math easy. The foot-to-inch ratio is exact and doesn't involve any rounding.
Since the 1959 international yard-pound agreement, the inch is defined as precisely 25.4 mm (= 2.54 cm). This makes inch-to-metric conversions exact — no approximation needed. The older British inch was about 0.0001% different and is no longer used.
Construction in the US uses fractions of an inch: 1⁄2, 1⁄4, 1⁄8, 1⁄16. The 1⁄16 inch (≈ 1.6 mm) is the carpentry industry standard for finished work. Finer work uses 1⁄32 or 1⁄64; framing rough cuts can use 1⁄8 or 1⁄4.
When in doubt, convert everything to total inches first (no mixed feet-and-inches). Total inches as a single decimal number is unambiguous and easy to add, subtract, or compare. Convert back to feet+inches only at the end, when you need to communicate the result to someone.
Memorize these and you can convert between any height units without a calculator — though the calculator above handles the fractional rounding for you.
The foot is divided into exactly 12 inches. To convert a mixed measurement like 5 ft 10 in, multiply the feet by 12 and add the inches: (5 × 12) + 10 = 70 inches.
A standard interior door is 6 ft 8 in tall. In total inches: (6 × 12) + 8 = 72 + 8 = 80 inches. This matches the IRC building code specification of 80" for interior doors.
The inch is defined as exactly 2.54 cm. Dividing the cm value by 2.54 gives an exact-in-principle conversion — any rounding error is just from display precision.
A 178 cm person: 178 ÷ 2.54 = 70.0787… inches. Rounded to the nearest inch: 70 in = 5 ft 10 in. For construction work, the nearest 1⁄16 in: 70 5⁄64 in ≈ 70 1⁄16 in.
Since 1 m = 100 cm and 1 in = 2.54 cm, dividing gives 1 m = 100 ÷ 2.54 = 39.3700787… inches. The decimal repeats; use enough digits for the precision you need.
A 1.83 m person: 1.83 × 39.37 = 72.05 inches. Rounded: 72 in = 6 ft 0 in. Building code minimum hallway width is often given as 0.91 m, which equals 35.83 in or roughly 36 in (3 ft).
Divide by 12 and take the integer part as feet; the remainder is the inch portion. For non-integer total inches, the remainder may have a decimal — round to the nearest 1⁄16 in for construction.
Converting 100 inches to feet and inches: 100 ÷ 12 = 8 remainder 4, so 100 in = 8 ft 4 in. For 100.5 in: 8 ft 4.5 in, or 8 ft 4 8⁄16 in = 8 ft 4 1⁄2 in in construction notation.
These approximations are close enough for everyday use and let you skip the calculator for ballpark estimates. Errors below are vs the exact value.
| From | Quick estimate | Exact value | Error |
|---|---|---|---|
| 1 cm | ≈ 0.4 in | 0.39370 in | 1.6% |
| 1 inch | = 2.5 cm | 2.54 cm | 1.6% |
| 1 meter | ≈ 39 in (3 ft 3 in) | 39.37 in | 0.9% |
| 1 foot | ≈ 30 cm | 30.48 cm | 1.6% |
| 10 cm | ≈ 4 in | 3.937 in | 1.6% |
| 100 cm | ≈ 40 in (3 ft 4 in) | 39.37 in | 1.6% |
| 6 ft | ≈ 1.8 m | 1.829 m | 1.6% |
| 1 mm | ≈ 1⁄25 in | 0.0394 in | 1.5% |
Heights you encounter regularly: human height percentiles, standard architectural dimensions, and recognizable thresholds. The fractional inch shown is the nearest 1⁄16 inch.
| Description | ft / in | Total in | Centimeters | Meters |
|---|---|---|---|---|
| Very short adult | 5'0" | 60 in | 152.4 cm | 1.524 m |
| Short adult woman | 5'2" | 62 in | 157.5 cm | 1.575 m |
| Avg adult woman (US) | 5'4" | 64 in | 162.6 cm | 1.626 m |
| Tall adult woman | 5'8" | 68 in | 172.7 cm | 1.727 m |
| Avg adult man (US) | 5'9" | 69 in | 175.3 cm | 1.753 m |
| Often-cited 'tall' | 6'0" | 72 in | 182.9 cm | 1.829 m |
| Very tall adult man | 6'4" | 76 in | 193.0 cm | 1.930 m |
| Standard interior door | 6'8" | 80 in | 203.2 cm | 2.032 m |
| Exterior door (typical) | 6'10" | 82 in | 208.3 cm | 2.083 m |
| Standard ceiling (res.) | 8'0" | 96 in | 243.8 cm | 2.438 m |
| High ceiling | 9'0" | 108 in | 274.3 cm | 2.743 m |
| Vaulted / commercial | 10'0" | 120 in | 304.8 cm | 3.048 m |
Construction-grade fractions (down to 1⁄16 inch) with exact decimal and mm equivalents. Useful when reading rulers, transferring measurements between drawings, or interpreting imported metric specs.
| Fraction | Decimal in | Millimeters |
|---|---|---|
| 1⁄32 in | 0.03125 in | 0.794 mm |
| 1⁄16 in | 0.0625 in | 1.588 mm |
| 1⁄8 in | 0.125 in | 3.175 mm |
| 3⁄16 in | 0.1875 in | 4.763 mm |
| 1⁄4 in | 0.25 in | 6.35 mm |
| 5⁄16 in | 0.3125 in | 7.938 mm |
| 3⁄8 in | 0.375 in | 9.525 mm |
| 7⁄16 in | 0.4375 in | 11.113 mm |
| 1⁄2 in | 0.5 in | 12.7 mm |
| 9⁄16 in | 0.5625 in | 14.288 mm |
| 5⁄8 in | 0.625 in | 15.875 mm |
| 11⁄16 in | 0.6875 in | 17.463 mm |
| 3⁄4 in | 0.75 in | 19.05 mm |
| 13⁄16 in | 0.8125 in | 20.638 mm |
| 7⁄8 in | 0.875 in | 22.225 mm |
| 15⁄16 in | 0.9375 in | 23.813 mm |
| 1 in | 1.0 in | 25.4 mm |
Different industries and countries default to different systems. Knowing which is used where saves you from converting unnecessarily — and from missing a unit-mismatch bug.
The inch divides into 1⁄2, 1⁄4, 1⁄8, 1⁄16, 1⁄32, 1⁄64 — fractions designed for easy mental math with common construction divisions. 1 in = 2.54 cm exactly.
Decimal-based and used in most of the world. 1 m = 100 cm = 1000 mm. Precision steps by powers of 10, not by halves and quarters.
| Property | Inches | Centimeters |
|---|---|---|
| Smallest practical unit | 1⁄64 in ≈ 0.4 mm | 1 mm = 0.0394 in |
| Typical construction grid | 1⁄16 in (1.59 mm) | 1 mm or 5 mm |
| Body-height precision | 1 in (= 2.54 cm) | 1 cm (≈ 0.4 in) |
| Architectural drawing scale | ft/in (e.g., 1":1ft) | mm or m (e.g., 1:50) |
| Easy fractional math | Yes — halves, quarters | No — decimal only |
| Easy decimal math | Awkward (base 12) | Native (base 10) |
Beyond just converting your own height, knowing how to translate between inches and metric height units comes up surprisingly often.
Standard US interior doors are 80 inches; ceilings 96 inches; lumber is dimensioned in inches (a 2×4 is actually 1.5 × 3.5 in). When working from European or Asian metric drawings, every dimension needs converting. A 2438 mm ceiling becomes 96 in (8 ft) — the standard residential US height. Construction tolerance is typically ±1⁄16 in, so accurate conversion to fractional inches matters for orderable lumber and ready-cut materials.
Medical records in the US store height in inches (or feet+inches); the rest of the world uses centimeters. Pediatric growth charts (CDC) plot height-for-age in both. Drug dosing for some medications scales with height, so conversion errors can have real consequences. Recording a height as '173 in' instead of '173 cm' would be a 4.4× overdose for height-scaled drugs.
NBA roster heights are listed in feet and inches; FIBA and international rosters in centimeters. Comparing players across leagues requires conversion. A 6'9" NBA forward is 205.7 cm; the FIBA equivalent is usually rounded to 206 cm. NFL combine data, by contrast, lists heights in inches with 1⁄8 in precision (e.g., 6'2 5⁄8"), reflecting the importance of small differences for athletic scouting.
IKEA dimensions are in centimeters; US-sold furniture lists inches; imported European furniture often uses both. Doorway and stairway clearances for moving furniture need conversion — that '80 cm wide chair' won't fit through a 30-inch (76 cm) doorway, even though 80 looks bigger than 30. DIY plans from international sources (UK, Australia) mix the systems freely.
For any work where a 1-2% error matters (construction, medical, engineering), always use 1 in = 2.54 cm exactly — never 2.5 or '≈ 2.5'. A 6-foot height is 72 in = 182.88 cm; using 2.5 gives 180 cm, an almost-3 cm error. The factor 2.54 is also exact by international definition, so there's no excuse to round it.
When adding or comparing heights in mixed units, convert all of them to either total inches or centimeters first. Trying to add '5 ft 10 in + 1.83 m' in your head is error-prone; converting to 70 in + 72.05 in = 142.05 in is straightforward. Always pick the canonical unit and convert at the start, not at the end.
Construction work needs 1⁄16 in (≈ 1.6 mm) precision; cabinetry maybe 1⁄32 in; framing can be 1⁄8 in. Medical records use whole inches or 0.5 in. Casual personal height is fine to the nearest inch. Don't quote 5 ft 10.2 in to a clothing store — they're rounding to the nearest inch anyway.
When ordering or marking lumber, drywall, or trim, the dimensions are always in fractional inches (1⁄16 minimum). Converting 178 cm to 70.0787 in then rounding to 70 1⁄16 in gives you something you can transfer directly to a measuring tape. Decimal inches require mental conversion every time you use a ruler.
If you compute that a doorway is '7 in tall' or 'a ceiling is 240 in', step back and check units. A doorway of 7 in is 18 cm — clearly wrong; the value was probably feet. A 240-inch ceiling is 20 ft (6 m) — possible for a vaulted space but check whether 240 was meant as cm (95 in / 7 ft 11 in, more reasonable). Order-of-magnitude errors often signal a unit confusion.
The approximation 1 in ≈ 2.5 cm has a 1.6% error. On a 70-inch height, that's 1.1 cm difference — enough to misidentify someone's height bracket. Use the exact 2.54 cm/in for any work where the result will be compared or recorded.
The apostrophe is feet, the double-quote is inches. So 5'10" = 5 feet AND 10 inches, totaling 70 inches — NOT 5.10 feet (= 5 ft 1.2 in = 61.2 in). This is a very common error when computing heights from a list of strings like '5'10"' — strip the symbols carefully and treat the two numbers separately.
A height listed as '178' is centimeters (5'10") in metric countries but could be confused for inches (14'10"!) by an American. Always check the magnitude: human heights are 150-200 cm or 60-78 in. Anything outside that range probably has the wrong unit attached.
If you have a precise inch measurement, convert to cm with full precision and round at the end. Going '5 ft 10 in = 70 in → 178 cm → 70.08 in' loses information; '70 in → 177.8 cm' is exact. The intermediate-rounding error compounds when you do multiple conversions in sequence.
When converting decimal inches back to feet+inches, the rounded inch part might equal 12. Example: 71.99 in rounds to '5 ft 12 in' which should actually be '6 ft 0 in'. Construction-grade conversions need to roll over when the inches part hits 12, and again when the fractional part rounds to 16⁄16. The calculator above handles this correctly.
5 foot 6 (5'6") is 66 inches total. The math: (5 × 12) + 6 = 60 + 6 = 66. In centimeters: 66 × 2.54 = 167.64 cm. This is about the average adult height worldwide and slightly below average for US women (5'4") and well below US men (5'9"). It corresponds to the 50th percentile for women in many populations.
6 feet equals 72 inches, which is 182.88 cm (often rounded to 183 cm). In meters: 1.8288 m, usually written as 1.83 m. 6 feet is a commonly cited 'tall' threshold for adult men, falling roughly at the 86th percentile in the US. In countries that use metric, 'six feet tall' translates to 'about 1.83 m' in casual speech.
Statistically, 5'10" (70 in / 177.8 cm) is just above the US adult male average (about 5'9" or 69 in) and well above the US adult female average (about 5'4"). In a global context, 5'10" is taller than average for most populations. Whether it 'feels' tall depends on context — it's average-plus for American men, tall for many populations in Asia and Latin America, and shorter than average in the Netherlands (where adult men average about 6 ft).
Standard US interior doors are 80 inches tall (6 ft 8 in / 2.03 m). Standard exterior doors are often 82 in (2.08 m) but can be 80 in too. The width is typically 24, 28, 30, 32, or 36 in. These dimensions come from the International Residential Code and have been steady for decades, designed so that a tall person (up to about 6 ft 5 in) can walk through without ducking, with room for hardware and frame.
Standard residential ceiling height in the US is 96 inches (8 ft / 2.44 m). 9-foot ceilings (108 in / 2.74 m) are common in newer construction and considered an upgrade. 10-foot (120 in) is luxury. Older homes sometimes have 7-foot ceilings (84 in). Building code minimum for habitable rooms in the IRC is 7 ft, but most rooms are designed at 8 ft minimum because shorter feels cramped.
178 cm converts to 70.0787… inches, which rounds to 5 feet 10 inches (70 in) almost exactly. The conversion: 178 ÷ 2.54 = 70.0787 in; then 70 ÷ 12 = 5 ft remainder 10 in. This is one of the cleanest cm-to-imperial round-trip values, which is why '178 cm = 5'10"' is so frequently quoted as a reference height. To the nearest 1⁄16 in for construction, 178 cm = 70 1⁄16 in.
Multiply the feet by 12 and add the inches portion. For example, 5 ft 10 in = (5 × 12) + 10 = 70 inches. The factor 12 comes from the definition: 1 foot = 12 inches exactly. For mixed measurements like 5 ft 10½ in, just include the fractional inches in the addition: (5 × 12) + 10.5 = 70.5 inches. This is a one-step calculation with no rounding error.
Divide centimeters by 2.54. The relationship 1 inch = 2.54 cm is exact by international agreement (1959 yard-pound agreement), so this conversion has no rounding error in principle. For example, 178 cm ÷ 2.54 = 70.0787… inches, which rounds to 70.08 inches for everyday use, or 70 inches even (5 ft 10 in) if you're matching to the nearest standard height. Most height-conversion errors come from using approximate factors like 2.5; the exact 2.54 makes a real difference at typical heights.
Multiply meters by 39.3700787… (which is 100 ÷ 2.54). The conversion goes: 1 m = 100 cm = 100 ÷ 2.54 in ≈ 39.37 inches. So a height of 1.78 m × 39.37 = 70.07 inches. For construction precision, use the full factor 39.3700787 to avoid round-trip errors. For mental math, '1 meter is about 39.4 inches' is a useful approximation accurate to within 0.1%.
Construction typically rounds to the nearest 1⁄16 inch (about 1.6 mm). For example, 70.34 inches is closer to 70 5⁄16 in (which is 70.3125) than to 70 3⁄8 in (which is 70.375). Finer work (cabinetry, machining) may use 1⁄32 or 1⁄64; rougher work (framing) may use 1⁄8 or even 1⁄4. The calculator above shows the nearest 1⁄16 by default, which is the carpentry industry standard.
The international yard-pound agreement of 1959 redefined the inch as exactly 25.4 millimeters (which is 2.54 cm). Before that, the inch and other imperial units had slightly different values in different countries. The 1959 agreement, signed by the US, UK, Canada, Australia, New Zealand, and South Africa, made the inch identical worldwide. So 'inch' is now defined in terms of the metric meter — every inch is precisely 2.54 cm everywhere on Earth.
5 ft 10 in is 70 inches total. In centimeters: 70 × 2.54 = 177.8 cm. This is just above the historical US adult male average (about 5 ft 9 in or 175 cm) and roughly the global male average is closer to 5 ft 7 in (171 cm). For reference: 5'0" = 60 in = 152.4 cm; 5'6" = 66 in = 167.6 cm; 6'0" = 72 in = 182.9 cm; 6'6" = 78 in = 198.1 cm.
Standard residential ceiling height in the US is 96 inches (8 ft / 2.44 m). 'High ceilings' generally start at 108 in (9 ft) and go up to 120 in (10 ft) in luxury construction. Commercial spaces often use 9 to 10 ft. Standard interior door height is 80 in (6 ft 8 in / 2.03 m), and the recommended minimum head clearance is 84 in (7 ft / 2.13 m). These values matter when converting metric architectural drawings for US construction.
Yes. The conversions use the exact international definition (1 in = 2.54 cm), and the fractional inch output rounds to the nearest 1⁄16 in — the carpentry industry standard. The decimal display shows 3 decimal places for total inches (precision better than 1⁄32 in). For finer work like machining, switch to mils (1 mil = 0.001 in) or use the decimal value directly. The calculator does NOT account for material expansion, settling tolerance, or surveying accuracy — those are separate concerns.
All conversions use the exact international yard-pound agreement of 1959, which defines 1 inch = 25.4 mm = 2.54 cm precisely. The foot is defined as exactly 12 inches; the yard as exactly 3 feet; the mile as exactly 5280 feet. These definitions are universal across the US, UK, Canada, Australia, New Zealand, and South Africa — there is no longer a meaningful difference between an 'American inch' and a 'British inch' as there was before 1959. The fractional-inch output rounds to the nearest 1⁄16 in (the carpentry industry standard). For construction tolerances, the International Residential Code (IRC) specifies dimensions and minimums. For human height percentile context, US averages come from the CDC National Center for Health Statistics' Anthropometric Reference Data for Children and Adults (NHANES surveys).