Example 1
U = 12 V, I = 2 A, t = 60 s → W = 1440 J.
Electrical Work Calculator
Type U [V], I [A] and t [s]. The calculator computes W = U·I·t: 12 V, 2 A and 60 s is 1440 J, and 230 V and 1 A for 3600 s is 828,000 J. Negative time is refused.
Circuit power: P = U·I. Heat in a resistor: Q = I²·R·t.
Result
Voltage U (V), Current I (A) and Time t (s). The result shows up here.
How it works
Electrical work is the energy voltage and current deliver over time t: W = U·I·t. At 12 V, 2 A and 60 s you get 1440 J. A heater at 230 V and 1 A for one hour, 3600 s, is 828,000 J. At constant power that is the same as P·t, because P = U·I: 24 W for 60 s is again 1440 J.
The form has three fields in this order: voltage U in volts, current I in amperes, time t in seconds. The result is in joules. Type a minute as 60 and an hour as 3600, not as 1. A comma and a period mean the same current: 0,5 and 0.5.
Negative time will not run. Typed zero in U, I, or t gives W = 0: no voltage, no current, or no seconds. All three fields need a number before 1440 J appears. 1 kWh is 3,600,000 J (1000 W for 3600 s); this calculator stays in joules and does not convert to kWh.
Power P = U·I is on the neighbouring page, without time. Here energy in joules, there watts. Mechanical W = F·s uses the same joule unit and a different formula: force and distance there, a circuit here.
Joule heat Q = I² R t is another calculator. On a purely thermal resistor W and Q can be the same number. Here you compute work delivered to the circuit, not necessarily heat in the resistor.
USB at 5 V and 0.5 A for 120 s is 300 J. An LED at 3 V and 0.02 A for one hour is 216 J. Same joules, different scales: the calculator does not guess the device, it multiplies three field numbers.
How to use
- In the first field enter voltage U in volts. For example 12 on a USB rail or 230 at a wall outlet.
- In the second field enter current I in amperes, for example 2. In the third, time t in seconds, for example 60. One hour is 3600, not 1.
- Click Calculate. The calculator multiplies U·I·t. 12 V, 2 A and 60 s give 1440 J. 230 V, 1 A and 3600 s give 828,000 J.
- Negative time is rejected. Zero in any field gives W = 0. At constant power that is the same as P·t, where P = U·I.
- Want watts alone? Open power P = U·I. Heat in a resistor is on Q = I² R t. Here it stays delivered energy.
Formula
W = U · I · t
Alternatively at steady power: W = P · t with P = U · I. Unit: J.
W, U, I, and t for current
Electrical work here is W = U·I·t. 12 V, 2 A and 60 s is 1440 J. 230 V and 1 A for an hour is 828,000 J.
- W
- Work [J]. 12 × 2 × 60 = 1440 J. 1 kWh = 3,600,000 J; this calculator stays in joules.
- U
- Voltage [V]. 12 V or 230 V. Pair of P = U·I, here with t as well.
- I
- Current [A]. 2 A or 0.5 A. I must be a number.
- t
- Time [s]. 60 s or 3600 s. Negative t is refused.
Real-life examples
Example 2
One hour heater run: W = 828000 J.
Example 3
USB: W = 300 J.
Example 4
Short motor start: W = 2400 J.
Example 5
LED for one hour: W = 216 J.
Example 6
10 min: W = 36000 J.
Example 7
EV battery: W = 72000 J.
Example 8
9 V battery, half an hour: W = 1620 J.
Example 9
One minute: W = 27600 J.
Example 10
12 min: W = 43200 J.
Ways to use this calculator
- You compute 1440 J from 12 V, 2 A, 60 s.
- You check one hour of a heater: 230 V, 1 A, 3600 s.
Frequently asked questions
How much W at 12 V, 2 A and 60 s?
Work is 1440 J. That is 12 × 2 × 60. At power P = 24 W it is the same 24 × 60, only here the fields are U, I and t.
How much at 230 V, 1 A and 3600 s?
Work is 828,000 J. One hour at 230 V and 1 A, a 230 W heater for 3600 s.
Which units do I type?
Voltage U [V], current I [A], time t [s]. Result W [J]. Type an hour as 3600, not as 1.
How is this different from P = U·I?
Here energy W = U I t in joules. There power P = U I in watts, with no time field. Same U and I pair, different unknown.
Is this the same joule as W = F s?
Same unit W [J]. Different formula: a circuit with U, I and t here. Force and path there, with no amperes.
Does a comma in 0.5 A work?
Yes. 0.5 and 0,5 are the same I [A]. A comma and a period mean the same value.
Where is Joule heat?
On the Q = I² R t page. Here work delivered to the circuit, not necessarily heat on a resistor.
Is 1 kWh 3,600,000 J?
Yes. 1000 W for 3600 s. This calculator reports joules, not kilowatt-hours. 828,000 J is not yet 1 kWh.
What if t is negative?
The calculator refuses negative time. Zero seconds gives W = 0 J. U and I still need a number.
How much at 5 V, 0.5 A and 120 s?
Work is 300 J. That is 5 × 0.5 × 120. A small supply, two minutes.
Knowledge sources
The formula is the school one. Units follow SI; NIST SP 330 and BIPM define the measures, not your result.
Page updated in 2026.