Current Converter
Convert amperes, milliamperes and microamperes, with the charge-flow relationship shown explicitly — because an ampere is a coulomb per second, not a quantity of anything.
Current Converter
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Power figures assume a purely resistive load at unity power factor and are illustrative rather than design values.
- Current bands describe typical applications and are not circuit ratings or safety guidance.
- The charge card assumes steady current for the whole duration; real loads vary.
In short: Electric current converts through the ampere, which since the 2019 SI revision is defined by fixing the elementary charge: one ampere is one coulomb per second. The SI prefixes are exact powers of ten, so 1 mA is 0.001 A. Remember that current is a rate of flow, while a battery's ampere-hour rating is a quantity of charge — the two are separated by time.
Formula
Each factor is the number of amperes in one of that unit. The SI prefixes are exact powers of ten. The abampere, also called the biot, is exactly 10 A.
Worked Example
- Identify the source factor. One ampere is 1.
- Convert to the SI unit. 1 × 1 = 1 A.
- Identify the target factor. One milliampere is 0.001 A.
- Divide. 1 ÷ 0.001 = 1,000 mA.
- For charge, multiply by time. 1 A for 3,600 s moves 3,600 coulombs, which is exactly one ampere-hour.
What changed in 2019. The ampere was formerly defined by the force between two infinitely long parallel conductors one metre apart, an experiment nobody could actually perform. The revised SI instead fixes the elementary charge at exactly 1.602176634 × 10−19 C and derives the ampere from it, so one ampere is now precisely 6.241509074 × 1018 elementary charges per second. The practical value did not change; the definition became realisable.
Strengths & Limits Of This Model
Where this engine is strong
- Separates current as a rate from ampere-hours as a quantity, the distinction most battery confusion rests on.
- States the post-2019 definition of the ampere accurately rather than repeating the withdrawn parallel-conductor wording.
- Bridges directly into charge through Q = It.
Where it stops
- Does not handle AC power factor or harmonics.
- Not a cable-sizing or protection-coordination tool.
- Assumes steady current over the stated duration.
Practical Use Cases
Circuit protection and cable sizing
Breaker ratings, fuse selection and conductor current capacity are all specified in amperes, while datasheets for the loads are often in milliamperes.
Low-power and battery-operated design
Sleep-mode currents in microamperes determine standby life. Converting them into charge over a duty cycle gives the real capacity requirement.
Electrochemistry and plating
Deposition rate is governed by current through Faraday's laws, so plating and anodising specifications combine current with time.
Instrumentation loops
The 4 to 20 mA industrial signalling standard is a current loop precisely because current is unaffected by cable resistance — pair with the Resistance Converter when checking loop compliance.
Methodology & Editorial Standards
All conversions route through the ampere, one of the seven SI base units. Since the 2019 revision the ampere is defined by fixing the elementary charge at exactly 1.602176634 × 10⁻¹⁹ coulombs, replacing the earlier definition based on the force between parallel conductors. The SI prefixes are exact powers of ten. The abampere, also called the biot, is exactly 10 A in the electromagnetic CGS system, and the statampere is derived from the exact speed of light. The charge card applies Q = It and links to the charge converter rather than duplicating it. The power figures assume a purely resistive load at unity power factor and are illustrative only. Current bands are orientation and carry no safety authority. All conversion factors are exact by definition under the International System of Units, or exact by international agreement where the unit is defined by treaty. Values are held at full IEEE-754 double precision internally and rounded only for display, so chained conversions do not accumulate drift.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Current Converter — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
How many milliamps are in an amp?
Exactly 1,000, because milli is an exact SI prefix meaning one thousandth. There is no measurement uncertainty in this or any other prefix conversion on this page. A 2 A charger supplies 2,000 mA, and a 500 mA USB port supplies half an amp.
Is an amp the same as an amp-hour?
No, and the difference matters. An ampere is a rate of charge flow, one coulomb per second. An ampere-hour is a quantity of charge, specifically 3,600 coulombs. A 5 Ah battery does not deliver 5 A; it delivers one amp for five hours or five amps for one hour. Rate and quantity are separated by time.
How is the ampere defined now?
By fixing the elementary charge. Since May 2019 the SI defines the elementary charge as exactly 1.602176634 × 10⁻¹⁹ coulombs, and one ampere is the current that corresponds to about 6.241509 × 10¹⁸ of those charges passing a point per second. The previous definition used the force between two parallel conductors, which was impossible to realise directly.
What current is dangerous to a person?
Far less than most people expect. Currents of around 10 mA through the body can cause muscles to contract so that a person cannot let go, and currents in the region of 100 mA through the chest can induce ventricular fibrillation. Because body resistance varies enormously with skin condition and contact area, no voltage can be declared universally safe. Treat this as background, not guidance, and consult a qualified electrician.
Why is 4 to 20 mA used for industrial signals?
Because current is the same everywhere in a series loop regardless of cable resistance, so a long run does not weaken the signal the way a voltage signal would. The offset zero at 4 mA is deliberate: a reading of 0 mA means a broken wire rather than a legitimate zero measurement, which makes the failure mode detectable.
What is an abampere?
The unit of current in the electromagnetic CGS system, equal to exactly 10 amperes. It is also called the biot after Jean-Baptiste Biot. Along with the statampere from the electrostatic system it survives only in older physics literature and has no modern engineering use.
Does current get used up in a circuit?
No. Current is the same at every point in a series loop; the same electrons that leave the supply return to it. What gets used up is energy, converted into heat, light or motion as charge falls through a potential difference. The persistent idea that current is consumed by components is one of the most durable misconceptions in basic electricity.
How do I convert amps to watts?
Multiply by the voltage, since power is voltage times current. Amps alone cannot give watts, which is why a 13 A appliance draws about 2,990 W on a 230 V supply but a 15 A appliance draws only about 1,800 W on a 120 V supply. For AC circuits with motors or electronic loads you also need the power factor.