What formula does this calculator use?

The calculator uses E(J) = V(V) × Q(C). Voltage (V) is the potential difference in volts and Q is the electric charge in coulombs. One joule equals one volt times one coulomb (1 J = 1 V · C).

A coulomb (C) is the SI unit of electric charge. One coulomb equals the charge transported by a current of one ampere in one second (1 C = 1 A · s). For reference, a typical AA battery holds roughly 3,000–5,000 coulombs of charge.

How is this different from E = I × V × t?

They are equivalent. Charge Q = I × t (current × time), so E = V × Q = V × I × t. Use E = V × Q when you know the charge directly (e.g., from a capacitor spec), and E = I × V × t when you know current and time instead.

Can I calculate capacitor energy with this tool?

Yes. For a capacitor of capacitance C (farads) charged to voltage V, the stored charge is Q = C × V coulombs. Enter V and Q here to get the energy. Note that the full stored energy formula is E = ½ × C × V², which equals ½ × V × Q — half the V × Q product because the voltage ramps from 0 to V during charging.

A joule (J) is the SI unit of energy and work. One joule equals one newton-meter, one watt-second, or one volt-coulomb. It is also the energy dissipated as heat when one ampere flows through one ohm for one second.

What are the other energy units shown?

The result panel also displays kilojoules (1 kJ = 1,000 J), watt-hours (1 Wh = 3,600 J), and millijoules (1 mJ = 0.001 J) for convenience when working with very small or very large energy values.

Volts to Joules Calculator

Name: Volts to Joules Calculator
Availability: InStock
Author: Nham Vu

Enter voltage in volts and charge in coulombs to calculate energy in joules using E = V × Q.

Input Parameters

Voltage (V)

Charge (C)

Result

Enter values and press Calculate

Formula Reference

Energy

E (J) = V (V) × Q (C)

Charge

Q (C) = I (A) × t (s)

Unit Check

1 J = 1 V × 1 C

Result copied!

Summary

Enter voltage in volts and charge in coulombs to calculate energy in joules using E = V × Q.

How it works

Enter the voltage in volts (V).
Enter the electric charge in coulombs (C).
Click Calculate to apply the formula E = V × Q.
The result is displayed in joules (J) along with kilojoules and watt-hours.
Use the Reset button to clear all fields and start over.

Use cases

Calculate energy stored in a capacitor given its voltage and charge.
Determine energy delivered by a battery based on terminal voltage and charge drawn.
Verify joule output in electrostatic discharge (ESD) scenarios.
Compute energy in defibrillator or pulse-power systems.
Estimate work done moving a charge through a potential difference in circuit design.
Convert charge-voltage product to joules for physics homework and exams.
Analyze energy in charged particle accelerators.
Check energy balance in electrochemical cell reactions.

Frequently Asked Questions

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Last updated: 2026-05-23 · Reviewed by Nham Vu