Volts to mAh Calculator

How to Use Volts to mAh Calculator

Follow these simple steps to use the volts to mAh calculator effectively:

1. 1
   Enter Voltage: Input the nominal voltage (V) of your battery or device (e.g., 3.7V for a cell, 12V for a car battery).
2. 2
   Select Energy Unit: Use the dropdown next to the energy field to select your energy unit: Watt-hours (Wh), Milliwatt-hours (mWh), or Joules (J).
3. 3
   Enter Energy Value: Input the energy capacity of the battery or system in the selected unit.
4. 4
   Calculate: Click the Calculate to mAh button to run the conversion.

How to Calculate Volts to mAh (Conversion Guide)

To convert voltage (Volts) to battery capacity (milliamp-hours, mAh), you must understand that Volts and mAh measure two distinct physical properties: electrical potential difference and electric charge. Because of this, they cannot be converted directly without knowing the total energy capacity of the battery. This energy is typically specified in Watt-hours (Wh), Milliwatt-hours (mWh), or Joules (J).

By using the total energy, you can calculate the exact charge capacity. Doing so helps electrical engineers, device designers, and hobbyists size batteries properly for electronic systems and compare capacity ratings across different battery chemistries.

Real-Life Sizing Scenarios

Scenario 1: Sizing Smartphone Battery Capacity (3.7V Lithium-Ion)
A modern smartphone manufacturer lists their battery energy rating as 14.8 Watt-hours (Wh) at a nominal operating voltage of 3.7 Volts. To size the battery capacity in mAh, we use the standard Wh formula:
mAh = (14.8 Wh × 1000) ÷ 3.7 V = 4,000 mAh
This tells us the phone has a 4,000 mAh battery capacity.

Scenario 2: Sizing a Portable Power Station Battery (12V Lead-Acid/LiFePO4)
A camping power station or portable backup UPS is rated at 120 Wh and operates at 12 Volts. To find its capacity in milliamp-hours:
mAh = (120 Wh × 1000) ÷ 12 V = 10,000 mAh (which is equal to 10 Ah).
This helps you size standard DC loads that run off the 12V output port.

Step-by-Step Manual Sizing Guide & Formulas

To perform this calculation manually, follow these steps using the formula that corresponds to your energy unit:

Step 1: Determine your inputs. Identify the system voltage (V) and the total energy capacity. Let's assume you have a 5V USB output power bank rated at 50 Wh.

Step 2: Multiply the energy (Wh) by 1,000. This converts Watt-hours to milliwatt-hours (mWh):
50 Wh × 1,000 = 50,000 mWh

Step 3: Divide by the system voltage. Divide the mWh value by the nominal voltage (5V):
50,000 mWh ÷ 5 V = 10,000 mAh

Final Answer: The battery capacity at 5V is 10,000 mAh.

Volts to mAh Reference Conversion Chart

This table provides a quick lookup for converting standard system and battery voltages to capacity in milliamp-hours (mAh) based on common energy ratings (in Watt-hours, Wh).

12 volts to mah

A 12V voltage rating is standard for automotive lead-acid batteries, RV house batteries, boat electrical accessories, and small uninterruptible power supplies (UPS). To convert 12 volts to capacity in milliamp-hours (mAh), you need to divide the total energy capacity in Watt-hours by 12, then multiply by 1,000.

• Formula: mAh = (Wh × 1,000) ÷ 12
• For a 60Wh Backup Battery: Sizing capacity yields (60 × 1,000) ÷ 12 = 5,000 mAh.
• For a 600Wh Car Battery: Sizing capacity yields (600 × 1,000) ÷ 12 = 50,000 mAh (which is equal to 50 Ah).

3.7 volts to mah

A nominal potential of 3.7 Volts is the universal standard for rechargeable single-cell lithium-ion and lithium-polymer batteries. These are widely used in smartphones, tablets, rechargeable bluetooth speakers, and handheld power banks.

• Formula: mAh = (Wh × 1,000) ÷ 3.7
• For an 11.1Wh Smartphone Battery: Capacity sizing yields (11.1 × 1,000) ÷ 3.7 = 3,000 mAh.
• For a 37Wh Lithium Power Bank: Capacity sizing yields (37 × 1,000) ÷ 3.7 = 10,000 mAh.

1.5 volts to mah

A standard voltage rating of 1.5 Volts is common for standard household alkaline batteries (AA, AAA, C, and D sizes). These single-use batteries power low-drain devices such as TV remotes, wall clocks, and kitchen scales.

• Formula: mAh = (Wh × 1,000) ÷ 1.5
• For a 3.0Wh Alkaline AA Battery: Capacity sizing yields (3.0 × 1,000) ÷ 1.5 = 2,000 mAh.
• For a 1.5Wh Alkaline AAA Battery: Capacity sizing yields (1.5 × 1,000) ÷ 1.5 = 1,000 mAh.

5 volts to mah

5 Volts is the standard operating potential for USB charging grids, desktop/laptop ports, and smart accessory chargers. Converting 5V to mAh is vital when sizing capacity ratings for portable power banks or charging hubs.

• Formula: mAh = (Wh × 1,000) ÷ 5
• For a 50Wh USB Portable Charger: Capacity sizing yields (50 × 1,000) ÷ 5 = 10,000 mAh.
• For a 25Wh Backup Battery: Capacity sizing yields (25 × 1,000) ÷ 5 = 5,000 mAh.

48 volts to mah

A rating of 48 Volts is widely used in residential solar backup battery blocks, telecom server rooms, and light electric vehicles (LEVs) like high-speed e-bikes, electric scooters, and golf carts.

• Formula: mAh = (Wh × 1,000) ÷ 48
• For a 480Wh Server Backup Rack: Capacity sizing yields (480 × 1,000) ÷ 48 = 10,000 mAh (or 10 Ah).
• For a 960Wh E-Bike Battery: Capacity sizing yields (960 × 1,000) ÷ 48 = 20,000 mAh (or 20 Ah).

21 volts to mah

21 Volts is the peak charging voltage for 5-cell in series (5S) lithium battery packs. These packs are nominal 18V but are frequently marketed as "20V Max" or "21V peak" cordless power tools (like grass trimmers, leaf blowers, and drills). Battery Wh ratings are based on the nominal voltage, so divide by 18V, not the 21V peak (dividing by 21V would understate the capacity).

• Formula: mAh = (Wh × 1,000) ÷ 18
• For a 72Wh High-Power Power Tool Pack: Capacity sizing yields (72 × 1,000) ÷ 18 = 4,000 mAh.
• For a 36Wh Handheld Drill Battery: Capacity sizing yields (36 × 1,000) ÷ 18 = 2,000 mAh.

220 volts to mah

220 Volts is the standard AC household single-phase voltage used across Europe, Asia, Africa, and parts of South America. Sizing capacity at 220V is useful for solar grid-tied inverters and high-voltage home battery bank backup systems.

• Formula: mAh = (Wh × 1,000) ÷ 220
• For a 220Wh Appliance Load: Capacity sizing yields (220 × 1,000) ÷ 220 = 1,000 mAh.
• For a 1,100Wh Portable Solar Generator: Capacity sizing yields (1,100 × 1,000) ÷ 220 = 5,000 mAh.

convert volts to mah

To convert voltage (V) to battery capacity in milliamp-hours (mAh), you must use the total active energy stored in the cell, typically measured in Watt-hours (Wh). Milliamps and volts represent distinct measurements, meaning a direct conversion requires knowing the total work capacity of the storage cell.

• Standard Sizing Formula: mAh = (Wh × 1,000) ÷ Voltage
• Alternative Sizing Formula (using Joules): mAh = (Joules × 1,000) ÷ (Voltage × 3,600)

20 volts to mah

20 Volts is the highest fixed voltage of standard USB-C Power Delivery (PD) used to charge modern laptops. ("20V Max" garden tool batteries are 18V nominal, see above.) The results below are the charge delivered at the 20V output, ignoring conversion losses.

• Formula: mAh = (Wh × 1,000) ÷ 20
• For 100Wh Delivered at 20V USB-C PD: Capacity sizing yields (100 × 1,000) ÷ 20 = 5,000 mAh.
• For 80Wh Delivered at 20V: Capacity sizing yields (80 × 1,000) ÷ 20 = 4,000 mAh.

1588 volts to mah

1,588 Volts is not a standard system voltage. It is slightly above the 1,500 V DC level common in utility-scale battery storage and solar arrays, where high string voltages keep currents and losses low. The conversion works the same way at any voltage.

• Formula: mAh = (Wh × 1,000) ÷ 1,588
• For 1,588Wh of Stored Energy: Capacity sizing yields (1,588 × 1,000) ÷ 1,588 = 1,000 mAh.
• For 3,176Wh of Stored Energy: Capacity sizing yields (3,176 × 1,000) ÷ 1,588 = 2,000 mAh.

Frequently Asked Questions (FAQs)