Solar and electrical projects constantly require converting between volts, amps, watts, amp-hours, watt-hours, and kilowatt-hours. Each unit measures something different, and mixing them up leads to undersized wiring, blown fuses, or batteries that do not last as long as expected. Our free Electrical Unit Converter lets you enter any two known values and instantly calculates the rest — no formulas to remember.
What Each Unit Measures
Volts (V) measure electrical pressure — the force that pushes current through a circuit. Your home outlet is 120V or 230V depending on your country. Solar batteries are typically 12V, 24V, or 48V. Amps (A) measure current — the flow rate of electricity through a wire. Higher amps require thicker wire to avoid overheating. Watts (W) measure power — the rate of energy consumption. A 100-watt bulb consumes energy 10 times faster than a 10-watt LED. The relationship is the foundation of electrical engineering: Watts = Volts × Amps.
Amp-hours (Ah) measure charge capacity — how much current a battery can deliver over time. A 200 Ah battery can theoretically deliver 200 amps for 1 hour, or 10 amps for 20 hours. Watt-hours (Wh) measure energy — charge capacity multiplied by voltage. A 12V 200 Ah battery stores 2,400 Wh. Kilowatt-hours (kWh) are simply watt-hours divided by 1,000. Your electricity bill is measured in kWh. That same battery stores 2.4 kWh, and one kWh is one “unit” on your bill.
How to Use the Converter
Enter any two values you know and click Calculate. The tool derives everything it can from those inputs. For example, enter 12 volts and 200 Ah, and the converter shows energy as 2,400 Wh and 2.40 kWh. Add a load of 500 watts, and it also shows that the current draw is 41.7 amps. Leave fields empty for values you want calculated — the tool fills them in.
The Clear button resets all fields so you can run a new calculation without manually deleting each input. Results appear in a clean card layout with each value clearly labeled.
Common Conversions People Search For
Ah to kWh is the most common solar battery conversion. Multiply amp-hours by voltage, then divide by 1,000. A 12V 200 Ah battery = 2.4 kWh. A 12V 150 Ah battery = 1.8 kWh. A 12V 230 Ah battery = 2.76 kWh. A 48V 100 Ah LiFePO4 battery = 4.8 kWh. Remember that these are rated capacities — usable energy is lower after depth of discharge, as our Battery Backup Calculator shows.
Watts to amps is critical for wire sizing. A 3,000-watt load at 230V draws 13 amps (manageable on standard wiring). The same 3,000 watts at 12V draws 250 amps, requiring extremely thick cables. This is why higher-voltage battery systems (24V or 48V) are preferred for larger solar installations — lower current means thinner, cheaper, safer wiring.
kWh to Ah is useful when you know your daily energy need and want to know what battery capacity you require. If you need 5 kWh of storage at 48V: 5,000 Wh ÷ 48V = 104.2 Ah. Before depth of discharge and efficiency, you need a battery rated at least 104 Ah at 48V. After applying 90 percent DoD and 85 percent efficiency for LiFePO4, the required rated capacity is 104.2 ÷ (0.9 × 0.85) = 136 Ah.
The Formulas Behind the Tool
The converter uses six core relationships. Watts equals Volts times Amps. Amps equals Watts divided by Volts. Volts equals Watts divided by Amps. Watt-hours equals Amp-hours times Volts. kWh equals Watt-hours divided by 1,000. And Amp-hours from kWh equals kWh times 1,000 divided by Volts. The tool includes a quick-reference table of these formulas below the results so you can verify the math or use them independently.
These are DC (direct current) formulas. For AC circuits, power factor comes into play — the relationship between apparent power (VA) and real power (watts) is not 1:1 for motor loads. For AC conversions, use our kVA to Watts Converter which handles power factor properly.
Why Units Matter in Solar
Getting units wrong is how solar systems get mis-sized. A battery rated at 200 Ah sounds like a lot — but at 12V that is only 2.4 kWh, and after depth of discharge only about 1.0 to 1.8 kWh depending on chemistry. An inverter rated at 5 kVA sounds powerful — but at 0.8 power factor it delivers only 4,000 watts. A solar panel rated at 585 watts sounds productive — but after losses it generates about 2.3 kWh per day, not 585 × 24 hours. Every conversion in the solar sizing chain matters, and any unit error compounds through the rest of the system.
This is why our Solar System Calculator handles all these conversions internally — you enter appliances in watts and hours, and the tool converts through every step (kWh daily load → panel watts → battery Ah → inverter kVA → controller amps) using the correct formulas at each stage.
Convert Your Units Now
Our Electrical Unit Converter is the quick-reference tool for any solar or electrical project. Enter any two values, get the rest instantly. Bookmark it — you will use it every time you spec a cable, check a battery, or verify a panel’s output.
Open the Electrical Unit Converter →
⚡ Free Solar Sizing Cheat Sheet
Get our one-page guide to sizing panels, batteries and inverters — plus weekly solar tips. No spam, unsubscribe anytime.
By subscribing you agree to our privacy policy. We'll email your guide and occasional solar tips — never spam.
