Micrometer to Span Conversion Calculator: Free Online Tool
Convert micrometers to spans with our free online length converter.
Micrometer to Span Calculator
How to Use the Calculator:
- Enter the value you want to convert in the 'From' field (Micrometer).
- The converted value in Span will appear automatically in the 'To' field.
- Use the dropdown menus to select different units within the Length category.
- Click the swap button (⇌) to reverse the conversion direction.
How to Convert Micrometer to Span
Converting Micrometer to Span involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Micrometer = 4.3745e-6 spansExample Calculation:
Convert 10 micrometers: 10 × 4.3745e-6 = 4.3745e-5 spans
Disclaimer: For Reference Only
These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.
Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.
What is a Micrometer and a Span?
A micrometer, also known as a micron, is a unit of length equal to one millionth of a meter (1×10⁻⁶ m).
The Span is an ancient unit of length based on the distance across an outstretched human hand, measured from the tip of the thumb to the tip of the little finger (or sometimes the index finger). As an anthropomorphic unit, its length was inherently variable, depending on the size of an individual's hand.
Historically, it was often defined in relation to other body-based units:
- Typically considered half a cubit.
- Often equated to 3 palms (where a palm is the width of the hand across the base of the fingers).
- Sometimes defined as 12 digits (fingerbreadths).
A common, though unofficial, modern estimate for a span is around 9 inches or approximately 22.86 centimeters (cm).
Note: The Micrometer is part of the metric (SI) system, primarily used globally in science and trade. The Span belongs to the imperial/US customary system.
History of the Micrometer and Span
The term micron was officially accepted between 1879 and 1967 but later deprecated. Micrometer is the current standard term.
The span is one of the oldest informal units of measurement, used by numerous ancient civilizations, including the Egyptians, Israelites, Greeks, and Romans, due to the convenience of using the human hand.
- Ancient Egypt & Mesopotamia: The span was used alongside the cubit and digit. The relationship (often 1 span = 1/2 cubit) was fundamental in their systems.
- Biblical References: The span is mentioned in the Bible (e.g., Exodus 28:16 describing the High Priest's breastplate, Goliath's height in some interpretations).
- Ancient Greece & Rome: Used as a practical subdivision of the cubit.
- Medieval Europe: Continued in informal use and sometimes appeared in texts defining lengths. In England, it was often standardized (unofficially) as 9 inches.
Like other anthropomorphic units, the span fell out of official use with the development and adoption of more standardized systems like the Imperial (inches, feet) and Metric (meters) systems, which provided necessary precision for trade, science, and industry.
Common Uses for micrometers and spans
Explore the typical applications for both Micrometer (metric) and Span (imperial/US) to understand their common contexts.
Common Uses for micrometers
- Measuring microscopic objects (e.g., bacteria, cells)
- Precision engineering tolerances
- Semiconductor manufacturing
Common Uses for spans
The span is now obsolete for precise or official measurements but is still encountered or used in specific contexts:
- Informal Estimation: Used for quick, rough measurements of moderate lengths where precision is not critical (e.g., gardening, crafts, estimating object sizes).
- Historical Texts: Found in ancient and medieval documents, requiring understanding for interpretation.
- Anthropology & Archaeology: Relevant when studying historical measurement systems or interpreting dimensions from ancient sites.
- Figurative Language: Can be used metaphorically to denote a small distance or extent ("life span").
- Understanding Historical Units: Key to grasping the relationship between units like the digit, palm, and cubit in ancient systems.
Frequently Asked Questions
Questions About Micrometer (μm)
Is a micrometer the same as a micron?
Yes, 'micron' is an older, deprecated name for the micrometer (μm). Both refer to one millionth of a meter.
How many micrometers are in a millimeter?
There are 1,000 micrometers (μm) in 1 millimeter (mm).
What are some examples of things measured in micrometers?
Examples include the diameter of human hair (around 50-100 μm), bacteria (typically 1-10 μm), and the thickness of plastic bags.
About Span (span)
How long is a span?
There is no single, universally fixed length for a span because it's based on human hand size. However:
- A common historical and modern estimate is 9 inches (in).
- This is approximately 22.86 centimeters (cm) or 0.2286 meters (m).
- Historically, it was often defined as half a cubit, which varied (e.g., a common cubit of ~18 inches would yield a 9-inch span).
What is the relationship between a span and a cubit?
In many historical systems, a span was considered half (1/2) of a cubit. Since cubits themselves varied (e.g., common cubit vs. royal cubit), the exact length of the span derived this way also varied.
What is the relationship between a span and a palm or digit?
Common relationships, though varying by system, were:
- 1 span ≈ 3 palms (where a palm is the width of the hand).
- 1 span ≈ 12 digits (where a digit is the width of a finger).
Is the span an SI unit?
No, the span is not an SI unit. It is an ancient, non-standardized, anthropomorphic unit. The SI base unit for length is the meter (m).
Is the span still used today?
The span is not used for any official, scientific, or commercial measurements. Its use is limited to informal estimations, historical context, and figurative language. People might still use their own hand span for a quick size check.
Where does the name 'span' come from?
The word "span" comes from Old English spann, related to the verb spannan, meaning "to stretch, extend, or connect". This directly reflects the action of stretching the hand to measure the unit.
Conversion Table: Micrometer to Span
| Micrometer (μm) | Span (span) |
|---|---|
| 1 | 0 |
| 5 | 0 |
| 10 | 0 |
| 25 | 0 |
| 50 | 0 |
| 100 | 0 |
| 500 | 0.002 |
| 1,000 | 0.004 |
All Length Conversions
Other Units from Length
- Meter (m)
- Kilometer (km)
- Hectometer (hm)
- Decimeter (dm)
- Centimeter (cm)
- Millimeter (mm)
- Inch (in)
- Foot (ft)
- Yard (yd)
- Mile (mi)
- Nautical Mile (NM)
- Nanometer (nm)
- Light Year (ly)
- Astronomical Unit (AU)
- Parsec (pc)
- Angstrom (Å)
- Point (Typography) (pt)
- Mil/Thou (mil)
- Fathom (fath)
- Furlong (fur)
- Link (Gunter's) (li)
- Pace (pace)
- Digit (digit)
- Cable Length (cb)
- Ell (ell)
- Finger (finger)
- Roman Mile (m.p.)
- Stadion (stadion)
- Chi (Chinese) (chi)
- Shaku (Japanese) (shaku)
- Li (Chinese) (li)
- Toise (toise)
- Bolt (bolt)
- Rope (rope)
- Smoot (smoot)
- Sajene (sajene)
- Ken (ken)
- Wa (wa)
- Vara (vara)
- Aln (aln)
- Cubit (Royal/Egyptian) (cubit)
- Versta (versta)
- Arpent (arpent)
- Ri (Japanese) (ri)
- Klafter (klafter)
- Yojana (yojana)
- Skein (skein)