Current Conversion — fA · pA · nA · μA · mA · A · kA
A universal electric-current converter built around a horizontal bench-strip with seven labeled range cells. Type a value into any cell — femtoamps through kiloamps — and the active decade lights up while every neighbor shows the equivalent magnitude. Real-world presets include single ion channels (2 pA), op-amp input bias (10 pA), USB-C PD chargers (3 A), HVAC motors (25 A) and lightning bolts (30 kA). Formula: I_target = I_source × 10^(Δprefix).
Quick Conversion
Formula: I_to = I_from × 10^(p_from − p_to); 1 A = 1 C/s
Named current presets
Conversion Table (mA base)
| mA | μA | A | kA |
|---|---|---|---|
| 0.001 | 1 | 0.0000 | 1.00e-9 |
| 0.01 | 10 | 0.0000 | 1.00e-8 |
| 0.1 | 100 | 0.0001 | 1.00e-7 |
| 1 | 1,000 | 0.0010 | 1.00e-6 |
| 5 | 5,000 | 0.0050 | 5.00e-6 |
| 10 | 10,000 | 0.0100 | 1.00e-5 |
| 50 | 50,000 | 0.0500 | 5.00e-5 |
| 100 | 100,000 | 0.1000 | 1.00e-4 |
| 500 | 500,000 | 0.5000 | 5.00e-4 |
| 1000 | 1,000,000 | 1.0000 | 1.00e-3 |
| 5000 | 5,000,000 | 5.0000 | 5.00e-3 |
| 10000 | 10,000,000 | 10.0000 | 1.00e-2 |
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Formula card
I_target = I_source × 10^(p_src − p_tgt)fA=−15, pA=−12, nA=−9, μA=−6, mA=−3, A=0, kA=+3.
I = dQ/dt · 1 A = 1 C / sPer CGPM 2018: 1 A = 6.241509074... × 10¹⁸ elementary charges per second.
I = V / R12 V across 10 Ω gives 1.2 A = 1200 mA. The bench strip lights the A cell at this value.
From Ampère's 1820 Annales paper to the 2018 SI redefinition
In 2026, a bioelectronics engineer profiling a neural interface needs to confirm the pA stimulus current at the electrode does not exceed the mA safe-charge envelope — without juggling three SI prefix calculators. This bench strip is the universal current Rosetta Stone.
On 4 September 1820, François Arago presented to the Académie des Sciences in Paris a translation of Hans Christian Ørsted's Copenhagen experiment in which an electric current deflected a magnetic compass needle. André-Marie Ampère (1775-1836), then chair of mathematics at the École Polytechnique, was electrified. Within seven days he had derived the right-hand rule, the force between parallel current-carrying wires, and the theoretical basis for what we now call the magnetic field. His paper "Mémoire sur l'action mutuelle de deux courants électriques" appeared in the Annales de Chimie et de Physique in October 1820.
The unit was named in his honor at the First International Electrical Congress in Paris in 1881 — held in conjunction with the International Exposition of Electricity at the Palais de l'Industrie. The Congress also named the ohm, volt, coulomb and farad, establishing the ampere-volt-ohm system that became the foundation of modern electrical engineering. The 9th CGPM in 1948 made the ampere the SI coherent unit of electric current with an operational definition: the constant current that produces a force of 2 × 10⁻⁷ N/m between two parallel infinite wires 1 m apart in vacuum.
The 26th CGPM at Versailles in November 2018 effected the most radical change. The elementary charge e = 1.602176634 × 10⁻¹⁹ C was fixed exactly, and the ampere was redefined in terms of e per second — exactly 6.241509074... × 10¹⁸ electrons per second. Effective 20 May 2019, the ampere is no longer tied to a force measurement but to a count of electrons, traceable to natural law and reproducible in any laboratory with sub-attoampere precision via single-electron pumps.
The bench strip's 18-decade range reflects the entire span of practical electrical engineering. At the smallest, single-electron pumps in NIST and PTB labs reach 10⁻¹⁹ A precision. Patch-clamp instruments (Axon Instruments 200B, HEKA EPC10) measure 0.1-100 pA with sub-pA noise floor. Femtoammeters (Femto LCA-1K-3M) read 10 fA to 1 mA. The mid-range from μA to kA is owned by digital multimeters (Fluke 87V), clamp meters (Fluke 376) and Rogowski coils (PEM CWT for power-electronics testing).
At the kiloamp end, the bench strip caps at typical industrial-scale currents — arc furnaces, aluminum smelters, lightning. Beyond that, fusion-research devices like ITER's poloidal-field coils carry 45 kA per turn, and pulsed-power machines like Sandia's Z-machine peak at 26 MA over 100 ns. Those scales would need MA and GA cells on the strip; the present design covers the universal electrical-engineering range without ITER-specific extension.
Modern current metrology is rooted in the quantum-Hall effect (von Klitzing 1980, Nobel 1985) and the AC Josephson effect (Josephson 1962, Nobel 1973). NIST's programmable Josephson voltage standard combined with the quantum-Hall resistance standard yields ampere measurements at 10⁻⁹ relative precision. The bench-strip widget on this page visualizes the result of those measurements — every decade from fA to kA traceable to the fundamental constants fixed by the 26th CGPM in 2018.
Practical safety thresholds make the strip a critical reference. NFPA 70E (2024) classifies 5 mA as the let-go threshold for adults; 10 mA causes muscular freeze; 100 mA across the heart causes ventricular fibrillation; 1 A causes cardiac arrest. The mA cell on the strip is therefore the safety-critical decade — every electrician, EE and lab tech should internalize the 5-10-100-1000 mA progression that the bench strip visualizes in one glance.
How to use the bench strip
- Pick a cell. The seven cells fA, pA, nA, μA, mA, A and kA are each a decade. Click any to make it the input.
- Enter the current. The natural-magnitude cell lights up; smaller and larger cells show scientific-notation equivalents.
- Tap a real-world preset. Ion channel, LED, USB, motor, lightning and 6 more chips load named current values.
- Read all seven decades at a glance. The colored grid below the strip shows every conversion simultaneously.
- Save the reading. Press Save and the conversion drops into your per-tool local-storage history.
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What current-strip users say
“Single-channel currents at 2 pA and whole-cell at 200 nA are my daily working range. The bench strip lighting both the pA and nA cells simultaneously is the cleanest visualization I have seen — saves me sketching the scale on the whiteboard.”
“Sizing variable-frequency drives I jump from motor FLA in A to inrush in kA constantly. The HVAC and arc-welder presets are dead-on, and the kA cell with the lightning preset is a great teaching moment for protection coordination.”
“NFPA 780 air-terminal sizing depends on the 200 kA 95th-percentile lightning current. The lightning preset and the kA decade are exactly what I demo when training new engineers on strike-energy budgets.”
“Keithley 6517B picoammeter outputs in pA-fA are central to gate-leakage characterization. The Ampère 1820 history paragraph and the CGPM 2018 redefinition FAQ are exactly what I quote in audit reports for NIST traceability.”
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