How many amperes in 1 volt?

You cannot convert volts to amperes directly — they measure different quantities. Volts measure electrical pressure; amperes measure flow rate. The relationship is set by the load: I = V / R (Ohm's Law). 1 V across a 1 Ω resistor produces 1 A; across a 100 Ω resistor produces 0.01 A; across an open circuit produces 0 A. To answer "how many amps", you need both voltage AND resistance (or impedance for AC).

How many ampere in 1 volt?

The query "how many ampere in 1 volt" reflects the same misunderstanding — ampere and volt are independent SI units, related only via a load impedance: I = V / R. With R unknown, the answer is undefined.

How many ampere in 230 volt?

Same reasoning as for "how many ampere in 230 volt" generally: depends on the connected load. A 230 V outlet will deliver 0.05 A to a phone charger, ~10 A to a kettle, or up to 32 A to a high-power oven branch — the breaker rating sets the upper limit.

How many amperes in 230 volt?

Same answer — depends on the load. A typical 230 V residential circuit serves loads of 6–32 A: a phone charger draws ~0.05 A, a laptop ~0.5 A, a kettle ~10 A, an oven ~15–30 A. The breaker rating (e.g. 16 A) is the maximum current the circuit will carry before tripping. To compute: I = P / V for resistive loads, or I = P / (V·cos φ) for inductive loads. The calculator above does this directly when you select "V and P" as inputs.

How do you convert amperes to kVA?

For three-phase: kVA = √3 × V × A / 1000. For single-phase: kVA = V × A / 1000. Example: 100 A on a 480 V three-phase service: kVA = 1.732 × 480 × 100 / 1000 = 83.1 kVA. The same 100 A on a 240 V single-phase: kVA = 240 × 100 / 1000 = 24 kVA. The √3 factor comes from the three-phase line-to-line voltage relation. Use the calculator above with phase mode set correctly.

How do you convert amperes to kW?

kVA times power factor: kW = kVA × cos φ. So kW = √3 × V × A × cos φ / 1000 for three-phase, or kW = V × A × cos φ / 1000 for single-phase. With pure resistive load (cos φ = 1) the kVA and kW are equal. With inductive load (motor at cos φ = 0.85), kW is 85% of kVA. Example: 100 A on 480 V three-phase at PF 0.85: kW = 1.732 × 480 × 100 × 0.85 / 1000 = 70.6 kW.

How do you convert amperes to HP?

Convert to kW first, then divide by 0.7457 (kW per HP). For three-phase: HP = (√3 × V × A × cos φ × η) / 745.7, where η is motor efficiency. For a typical 75% efficient motor at 100 A, 480 V, 0.85 PF: HP = (1.732 × 480 × 100 × 0.85 × 0.75) / 745.7 ≈ 71 HP. For pure power conversion (no motor): HP = kW / 0.7457.

What is the formula for amperes?

Three forms depending on what you know. Ohm's Law: I = V / R (volts divided by resistance). Power form: I = P / V for DC, I = P / (V·cos φ) for single-phase AC, I = P / (√3·V·cos φ) for three-phase. From apparent power: I = (kVA × 1000) / V (1ph) or (kVA × 1000) / (√3·V) (3ph). The calculator above uses whichever form matches your given inputs.

Who is the unit "ampere" named after?

The ampere is named after André-Marie Ampère (1775–1836), French mathematician and physicist who founded the science of classical electromagnetism — what he called "electrodynamics". His work demonstrated that two parallel wires carrying current attract or repel each other depending on direction, which became the basis for the original 1948 SI definition of the ampere. The 2019 SI redefinition fixed the elementary charge e exactly, and the ampere now follows from e × Hz (charges per second).

Calculator · Electrical · SI base unit · Ampère 1820

Ampere

The ampere is the SI unit of electric current — coulombs per second of charge flow. The calculator below covers ampere to kVA, ampere to kW, ampere to volts, and ampere x volt conversions for DC, single-phase, and three-phase systems, plus the related ampere kw calculator, hp to ampere calculator, and ampere calculator 3 phase use cases. Includes ampere hour and ampere hours calculator workflows for battery sizing.

Use the ampere calculator

Pick your phase mode and the two values you know — voltage and power, voltage and resistance, etc. The calculator returns current in amperes plus all the related power units (kVA, kW, kVAR, HP, BTU/hr).

CALC.007 Universal Power · V · I · P · R · 3 modes · 6 solve combos

I know:[Given]

Voltage V[V]

Current I[I]

Power P[P]

Resistance R[R]

Pure DC: P = V · I. Resistance shown is V/I (Ohm's law equivalent).

Voltage V

— V

Current I

— A

Power P

— W

Resistance R

— Ω

Apparent power S: — kVA
Reactive power Q: — kVAR
Power factor used: —
Mechanical equivalent: — HP
Heat output: — BTU/hr

Show your work

P = V · I = ...

FORMULA · P = V · I (DC) SOURCE · OHM 1827 · IEEE STD 100

The ampere formula

Two main forms cover most practical cases — Ohm\'s Law for resistive loads, and the power equation for everything else.

Eq. 01 — Ohm's Law (current from voltage and resistance) SI · Ohm 1827

I = \frac{V}{R}

I: current, A
V: voltage, V
R: resistance, Ω

Eq. 02 — Current from power (DC, 1-phase, 3-phase) SI · IEEE Std 100

I_{DC} = \frac{P}{V} \qquad I_{1\phi} = \frac{P}{V \cdot \cos\varphi} \qquad I_{3\phi} = \frac{P}{\sqrt{3} \cdot V_{LL} \cdot \cos\varphi}

I: line current, A
P: active power, W
V: voltage (line-to-line for 3-phase), V
cos φ: power factor (1.0 for resistive), —

Eq. 03 — Ampere ↔ kVA conversion SI · IEEE / NEC

kVA_{1\phi} = \frac{V \cdot I}{1000} \qquad kVA_{3\phi} = \frac{\sqrt{3} \cdot V_{LL} \cdot I}{1000}

kVA: apparent power, kVA
V: line voltage, V
I: line current, A

Worked example: 100 A on 480 V three-phase service

An industrial panel pulling 100 A continuous on a 480 V three-phase system at power factor 0.85. Convert to all the standard power units.

Quantity	Formula	Substitution	Result
Apparent power S	√3 · V · I / 1000	1.732 × 480 × 100 / 1000	83.1 kVA
Active power P	S × cos φ	83.1 × 0.85	70.6 kW
Reactive power Q	√(S² − P²)	√(83.1² − 70.6²)	43.8 kVAR
Mechanical equivalent	kW / 0.7457	70.6 / 0.7457	94.6 HP
Annual energy at 100% duty	kW × 8760 hr	70.6 × 8760	618 MWh / yr
Annual cost at $0.10 / kWh	MWh × $100	618 × 100	$61 800 / yr

The same 100 A on a 240 V single-phase service would give only 24 kVA — less than a third — because there is no √3 factor and the voltage is half. This is why three-phase power dominates industrial service: more power for the same conductor current.

Ampere: comparison and differences

Term	Symbol / unit	What it measures	Used for
Ampere	A	Current — rate of charge flow (1 A = 1 C/s)	Conductor sizing, breaker rating, motor FLA
Milliampere	mA	0.001 A	Sensor, signal, protective relay current
Microampere	µA	10⁻⁶ A	Leakage current, ESD events
kiloampere	kA	1000 A	Short-circuit / fault current ratings (AIC)
Volt-ampere (apparent power)	VA / kVA	V × I (RMS), no PF correction	Transformer rating, UPS sizing
Active power (kW)	W / kW	VA × cos φ	Real energy use, billing, mechanical work
Reactive power (kVAR)	VAR	VA × sin φ	PF correction, capacitor bank sizing
Coulomb (charge, NOT current)	C	Total charge transferred	Electrochemistry, capacitor charge

Ampere quick reference

Term / question	Quick answer
Ampere meter	An analogue or digital instrument (clamp meter, panel ammeter) that measures current. Modern true-RMS ampere meters cover both AC and DC; clamp-on units measure without breaking the conductor.
Ampere examples	Common load currents — phone charger 0.5 A, laptop 1.5 A, microwave 12 A, electric kettle 12.5 A, hair dryer 12 A, induction motor (5 HP, 480 V 3-φ) 7.6 A, residential service entrance 100–200 A.
Fuse ampere	The fuse rating (in amperes) is the steady current the fuse will pass without opening. Fuses open above this rating per NEC 240.6 standard sizes — 1, 3, 5, 10, 15, 20, 25, 30, 35 A and so on.
Ampere hour calculator / ampere hours calculator	An ampere hour (Ah) is current × time. The calculator: required Ah = (load W × hours) / battery V, then divide by usable depth-of-discharge. See the battery runtime tool.
Ampere x volt = volt-ampere	Multiply ampere x volt to get volt-amperes (VA), the apparent power. For a 230 V × 16 A circuit: 3 680 VA = 3.68 kVA.
Ampere formula 3 phase	I = P / (√3 × V_LL × cos φ). For 50 kW at 480 V three-phase, PF 0.9: I = 50 000 / (1.732 × 480 × 0.9) = 66.8 A.
Ampere kw calculator / hp to ampere calculator	The same calculator above does both: enter kW (or HP × 0.7457 = kW), voltage, and PF; it returns line current in amperes.
10 ampere watt	A 10 ampere watt question: 10 A × 120 V = 1 200 W (resistive); 10 A × 240 V = 2 400 W; 10 A × 480 V × √3 × 0.9 PF (three-phase) = 7 481 W.

Related concepts on this site

Frequently asked questions

How many amperes in 1 volt?: You cannot convert volts to amperes directly — they measure different quantities. Volts measure electrical pressure; amperes measure flow rate. The relationship is set by the load: I = V / R (Ohm's Law). 1 V across a 1 Ω resistor produces 1 A; across a 100 Ω resistor produces 0.01 A; across an open circuit produces 0 A. To answer "how many amps", you need both voltage AND resistance (or impedance for AC).
How many ampere in 1 volt?: The query "how many ampere in 1 volt" reflects the same misunderstanding — ampere and volt are independent SI units, related only via a load impedance: I = V / R. With R unknown, the answer is undefined.
How many ampere in 230 volt?: Same reasoning as for "how many ampere in 230 volt" generally: depends on the connected load. A 230 V outlet will deliver 0.05 A to a phone charger, ~10 A to a kettle, or up to 32 A to a high-power oven branch — the breaker rating sets the upper limit.
How many amperes in 230 volt?: Same answer — depends on the load. A typical 230 V residential circuit serves loads of 6–32 A: a phone charger draws ~0.05 A, a laptop ~0.5 A, a kettle ~10 A, an oven ~15–30 A. The breaker rating (e.g. 16 A) is the maximum current the circuit will carry before tripping. To compute: I = P / V for resistive loads, or I = P / (V·cos φ) for inductive loads. The calculator above does this directly when you select "V and P" as inputs.
How do you convert amperes to kVA?: For three-phase: kVA = √3 × V × A / 1000. For single-phase: kVA = V × A / 1000. Example: 100 A on a 480 V three-phase service: kVA = 1.732 × 480 × 100 / 1000 = 83.1 kVA. The same 100 A on a 240 V single-phase: kVA = 240 × 100 / 1000 = 24 kVA. The √3 factor comes from the three-phase line-to-line voltage relation. Use the calculator above with phase mode set correctly.
How do you convert amperes to kW?: kVA times power factor: kW = kVA × cos φ. So kW = √3 × V × A × cos φ / 1000 for three-phase, or kW = V × A × cos φ / 1000 for single-phase. With pure resistive load (cos φ = 1) the kVA and kW are equal. With inductive load (motor at cos φ = 0.85), kW is 85% of kVA. Example: 100 A on 480 V three-phase at PF 0.85: kW = 1.732 × 480 × 100 × 0.85 / 1000 = 70.6 kW.
How do you convert amperes to HP?: Convert to kW first, then divide by 0.7457 (kW per HP). For three-phase: HP = (√3 × V × A × cos φ × η) / 745.7, where η is motor efficiency. For a typical 75% efficient motor at 100 A, 480 V, 0.85 PF: HP = (1.732 × 480 × 100 × 0.85 × 0.75) / 745.7 ≈ 71 HP. For pure power conversion (no motor): HP = kW / 0.7457.
What is the formula for amperes?: Three forms depending on what you know. Ohm's Law: I = V / R (volts divided by resistance). Power form: I = P / V for DC, I = P / (V·cos φ) for single-phase AC, I = P / (√3·V·cos φ) for three-phase. From apparent power: I = (kVA × 1000) / V (1ph) or (kVA × 1000) / (√3·V) (3ph). The calculator above uses whichever form matches your given inputs.
Who is the unit "ampere" named after?: The ampere is named after André-Marie Ampère (1775–1836), French mathematician and physicist who founded the science of classical electromagnetism — what he called "electrodynamics". His work demonstrated that two parallel wires carrying current attract or repel each other depending on direction, which became the basis for the original 1948 SI definition of the ampere. The 2019 SI redefinition fixed the elementary charge e exactly, and the ampere now follows from e × Hz (charges per second).

Sources and methodology

BIPM. The International System of Units (SI), 9th Edition, 2019. 2019 redefinition: ampere now derives from elementary charge e = 1.602176634 × 10⁻¹⁹ C exactly.
IEEE. IEEE Std 100 — Authoritative Dictionary of IEEE Standards Terms, 7th Edition.
NFPA. National Electrical Code (NEC) NFPA 70, 2023. Article 100 — definitions of ampere, voltage, voltage class.
NIST. NIST Reference on Constants, Units, and Uncertainty.
Ampère, A.-M. Mémoire sur les effets du courant électrique, 1820. Foundational electrodynamics paper.