Convert Amperes per Inch to Amperes per Meter
Ampere per Inch (A/in) to Ampere per Meter (A/m) linear current density conversion — enter any value below to get an instant result, or use the table for common values.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Result
1 A/in = 39.370079 A/m
1 Ampere per Inch = 39.370079 Amperes per Meter
1 Ampere per Meter = 0.0254 Amperes per Inch
1 A/in in every supported unit
Conversion chart: Ampere per Inch to Amperes per Meter
Conversion table
| Ampere per Inch (A/in) | Ampere per Meter (A/m) |
|---|---|
| 0.01 A/in | 0.39370079 A/m |
| 0.1 A/in | 3.9370079 A/m |
| 1 A/in | 39.370079 A/m |
| 2 A/in | 78.740157 A/m |
| 3 A/in | 118.11024 A/m |
| 5 A/in | 196.85039 A/m |
| 10 A/in | 393.70079 A/m |
| 20 A/in | 787.40157 A/m |
| 50 A/in | 1968.5039 A/m |
| 100 A/in | 3937.0079 A/m |
| 1000 A/in | 39370.079 A/m |
Ampere per Inch (A/in)
Definition: The US customary version of linear current density, expressing current per inch of length rather than per meter.
History: Used historically in American and British electrical engineering practice, where winding densities and current sheet dimensions were traditionally specified in inches rather than metric units.
Current use: Occasionally found in legacy US and UK electromagnet and motor-winding specifications quoting current per inch of coil length.
Ampere per Meter (A/m)
Definition: The SI derived unit of linear current density — the amount of electric current flowing per meter of width across a current sheet, or equivalently the SI unit of magnetic field strength H produced by a distributed current.
History: Derived directly from combining the SI base ampere with the meter once Maxwell's electromagnetic theory required a natural way to express current spread continuously across a surface, rather than concentrated in a single wire, and to quantify the magnetizing field such a current produces.
Current use: Used throughout electromagnetics and antenna theory to describe surface current sheets, the winding density of solenoids and electromagnets (turns per meter multiplied by current), and magnetic field strength H in magnetic circuit calculations.
Supported Units
| Unit | Symbol | In Ampere/Meter |
|---|---|---|
| Ampere per Meter | A/m | 1 A/m |
| Ampere per Centimeter | A/cm | 100 A/m |
| Ampere per Inch | A/in | 39.370079 A/m |
| Abampere per Meter | abA/m | 10 A/m |
| Abampere per Centimeter | abA/cm | 1000 A/m |
| Abampere per Inch | abA/in | 393.70079 A/m |
| Oersted | Oe | 79.577472 A/m |
| Gilbert per Centimeter | Gi/cm | 79.577472 A/m |
About These Parameters
- Value
- The linear current density value you want to convert, expressed in the "From" unit. Accepts decimals, and can represent anything from a small solenoid's winding density to a magnetic recording material's coercivity rating.
- From Unit
- The unit your input value is currently measured in — a modern calculation's ampere-per-meter figure, or a magnetics datasheet's oersted or gilbert-per-centimeter rating.
- To Unit
- The unit you want the result converted into. Use the swap button to flip From and To instantly, which is handy when translating an oersted-based magnetics spec into the modern SI ampere per meter or vice versa.
How Linear Current Density Conversion Works
The Formula
Every unit here is defined by a fixed multiplier relative to ampere per meter. To convert a value from one unit to another:
result = value × (factor of "From" unit ÷ factor of "To" unit)
For Ampere per Inch → Ampere per Meter: multiply by 39.370079. For example, 1 A/in × 39.370079 = 39.370079 A/m.
Ampere per Meter and Magnetic Field Strength
Ampere per meter is not just an abstract "current spread over a length" unit — it is literally the SI unit of magnetic field strength H, the quantity that describes how strongly a current magnetizes the space around it, independent of the material present. Wrapping a wire N times around a core carrying current I produces a field strength directly related to N × I divided by the length of the winding, expressed in amperes per meter. For decades before SI unification, magnetics engineers instead worked in oersteds and gilberts per centimeter — CGS-Gaussian units that remain deeply embedded in the magnetics industry even today, which is why permanent-magnet and recording-media coercivity is still commonly rated in oersteds on otherwise SI-based datasheets.
Oersted and Gilbert per Centimeter
The oersted (named after Hans Christian Ørsted, who discovered electromagnetism in 1820) and the gilbert per centimeter (named after William Gilbert, the pioneering 16th-century researcher of magnetism) are numerically identical CGS-Gaussian units, both equal to about 79.577 A/m. They express the same underlying magnetic field strength concept from two angles: the oersted was defined directly as a CGS field-strength unit, while the gilbert per centimeter arrives at the same value by dividing the gilbert (a unit of magnetomotive force, the magnetic analogue of electromotive force) by a centimeter of magnetic path length.
Example
A linear current density of 1 A/in equals 39.370079 A/m. For scale, a small electromagnet coil might operate around a few hundred ampere-turns per meter, while a magnetic recording medium's coercivity is often rated in the hundreds to low thousands of oersteds.
Frequently Asked Questions
How many Amperes per Meter are in 1 Ampere per Inch?
1 Ampere per Inch (A/in) equals exactly 39.370079 Amperes per Meter (A/m).
What is linear current density used for?
Linear current density (ampere per meter) describes electric current distributed along a length — for example, the turns of a solenoid winding or the edge of a current sheet — and is also the SI unit of magnetic field strength H, used to calculate how strongly a coil or current sheet magnetizes the surrounding space.
Why are oersted and gilbert per centimeter numerically equal?
Both units come from the same CGS-Gaussian unit system and describe magnetic field strength from equivalent definitions — the oersted directly, and the gilbert per centimeter as magnetomotive force divided by path length. Since the CGS system defines the gilbert and oersted consistently with each other, dividing gilberts by centimeters always produces a value numerically equal to the oersted.
Why do magnetics datasheets still use oersteds instead of SI units?
The oersted became deeply embedded in the magnetics and recording-media industries throughout the 20th century, and coercivity specifications for permanent magnets, magnetic tape, and hard-disk media continue to be quoted in oersteds by industry convention, even though the equivalent SI ampere-per-meter value is equally valid.
How does abampere per meter differ from ampere per meter?
Abampere per meter uses the CGS-electromagnetic current unit (the abampere, equal to 10 amperes) divided by an SI meter, making it exactly 10 times larger than ampere per meter for the same physical current distribution. It is a hybrid unit rarely used outside older transitional scientific literature.