How do I convert mAh to Wh?

Multiply the milliamp-hours by the voltage in volts, then divide by 1000. The formula is Wh = mAh × V / 1000.

Can I convert Wh back to mAh?

Yes. Divide the watt-hours by the voltage and multiply by 1000. The formula is mAh = Wh × 1000 / V.

What if I only have amp-hours (Ah), not milliamp-hours (mAh)?

Convert Ah to Wh by multiplying amp-hours by voltage. To go from Ah to mAh, multiply the Ah value by 1000.

Do I need to know the battery voltage to use these calculators?

Yes, voltage is required. The conversion links the charge unit (mAh or Ah) to energy unit (Wh) using the formula energy = charge × voltage.

Which tool should I use if I also need runtime estimates?

Active Calculator includes runtime, C-rate, and discharge current calculations alongside the basic conversions, making it suitable for battery bank or e-bike planning.

Miscellaneous Calculators6 options compared

Battery Capacity Calculator

Converts milliamp-hours (mAh) to watt-hours (Wh) by requiring voltage input, utilizing the fundamental relationship that links battery capacity units of Ah and Wh. The tool provides a clear explanation of the necessary formula alongside direct fields for entering values. It also offers reverse conversion functionality, ensuring users can easily move between different standard battery measurement...

Tech and electronics calculators

Editors’ Top PickBased on community votes

RapidTables

rapidtables.com

This calculator converts milliamp-hours (mAh) to watt-hours (Wh) using voltage, which is the same battery-capacity re...

Open RapidTables Read review →

Other OptionsRanked by votes

02
02
Active Calculator
activecalculator.com
This battery capacity calculator converts between amp-hours and watt-hours and supports runtime-related battery calcu...
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03
03
Inch Calculator
inchcalculator.com
This calculator converts amp-hours (Ah) to watt-hours (Wh) using battery voltage. The same page also links directly t...
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04
04
Omni Calculator
omnicalculator.com
Battery capacity calculator converts between amp-hours and watt-hours.
Open site View details
05
05
Convert-Formula
convert-formula.com
This page provides two-way conversion between amp-hours and watt-hours with voltage input. It includes both direction...
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06
06
Footprint Hero
footprinthero.com
This tool converts watt-hours to amp-hours from a user-entered voltage and also links to the reverse Ah-to-Wh convers...
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Side by side

Battery Capacity Calculator options compared

Tool	Best for	Strengths	Limitations
RapidTables rapidtables.com	Quick mAh/Wh conversion	Free, no signup Both conversion directions on one page Clear formula display	No runtime or C-rate calculations Basic design only
Active Calculator activecalculator.com	Runtime and C-rate calculations	Runtime, C-rate, discharge current Supports lithium, lead-acid, LiFePO4 Browser-based, free	More fields to fill out Less focused on simple mAh/Wh conversion only
Inch Calculator inchcalculator.com	Ah-to-Wh with reference tables	Ah-to-Wh conversion only Worked examples and reference tables Includes reverse Wh-to-Ah link	Focuses on Ah not mAh Fewer unit options than RapidTables
Omni Calculator omnicalculator.com	General unit conversion	Converts between Ah and Wh Straightforward input Part of a large calculator network	Community votes low (3) Excerpt thin; exact features unclear from material
Convert-Formula convert-formula.com	Two-way Ah/Wh conversion	Both directions on one page Free and openly accessible Simple formula display	Fewer features Community votes low (2)
Footprint Hero footprinthero.com	Wh-to-Ah with charts at common voltages		Focuses on Wh-to-Ah, not mAh-to-Wh Limited to common voltage charts only

Buyer's guide

How to choose a battery capacity calculator

When picking a battery capacity calculator, first decide which direction you need: mAh to Wh or Ah to Wh. If you only need a simple conversion with voltage, choose a tool that has direct input fields for charge and voltage and shows the formula. If you also need to estimate how long a battery will run a device, calculate C-rate, or see discharge current, look for a tool that includes runtime and runtime-related fields. The voltage value is the critical number that links the two unit systems, so make sure the calculator requires it.

Questions

Battery Capacity Calculator FAQ

How do I convert mAh to Wh?: Multiply the milliamp-hours by the voltage in volts, then divide by 1000. The formula is Wh = mAh × V / 1000.
Can I convert Wh back to mAh?: Yes. Divide the watt-hours by the voltage and multiply by 1000. The formula is mAh = Wh × 1000 / V.
What if I only have amp-hours (Ah), not milliamp-hours (mAh)?: Convert Ah to Wh by multiplying amp-hours by voltage. To go from Ah to mAh, multiply the Ah value by 1000.
Do I need to know the battery voltage to use these calculators?: Yes, voltage is required. The conversion links the charge unit (mAh or Ah) to energy unit (Wh) using the formula energy = charge × voltage.
Which tool should I use if I also need runtime estimates?: Active Calculator includes runtime, C-rate, and discharge current calculations alongside the basic conversions, making it suitable for battery bank or e-bike planning.

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