Ah to mAh Conversion Calculator
Convert Ampere-Hours to Milliampere-Hours Instantly - Free Battery Capacity Converter
Understanding Ah to mAh Conversion
The ampere-hour (Ah) to milliampere-hour (mAh) conversion is one of the most common battery capacity calculations in consumer electronics and electrical engineering. Both units measure electric charge capacity, but they differ by a factor of 1,000. Understanding this conversion is essential when comparing battery specifications, selecting replacement batteries, or designing portable electronic devices.
This conversion calculator provides instant, accurate results for converting between ampere-hours and milliampere-hours, helping consumers, engineers, technicians, and students quickly translate battery capacities between these two widely used units. Whether you're shopping for smartphone batteries, power banks, or understanding your device specifications, this simple conversion is fundamental to making informed decisions about battery capacity.
Conversion Formula
The mathematical relationship between ampere-hours and milliampere-hours is straightforward and based on the metric prefix "milli-" which means one thousandth.
Basic Conversion Formula:
\[ mAh = Ah \times 1{,}000 \]
Fundamental Relationship:
\[ 1 \text{ Ah} = 1{,}000 \text{ mAh} \]
Reverse Conversion:
\[ Ah = \frac{mAh}{1{,}000} \]
Where:
- Ah = Electric charge capacity in ampere-hours
- mAh = Electric charge capacity in milliampere-hours
- 1,000 = Conversion factor (milli- prefix means 1/1000)
Key Fact: 1 ampere-hour equals exactly 1,000 milliampere-hours because "milli-" is a metric prefix meaning one thousandth (1/1000). Therefore, 1 Ah = 1,000 mAh, following the standard metric system convention.
How to Convert Ah to mAh: Step-by-Step Guide
Converting ampere-hours to milliampere-hours is one of the simplest unit conversions you'll encounter:
- Identify Your Value: Find the battery capacity rating in ampere-hours (Ah) from the battery label or specifications.
- Apply the Conversion Factor: Multiply the ampere-hour value by 1,000.
- Calculate the Result: Perform the multiplication to obtain milliampere-hours (mAh).
- Verify Your Answer: The mAh value should be 1,000 times larger than the Ah value.
- Round Appropriately: Round to a sensible number of significant figures for practical use.
Example Calculation 1:
Convert 2.5 Ah (common smartphone battery) to mAh:
\[ mAh = 2.5 \times 1{,}000 = 2{,}500 \text{ mAh} \]
A 2.5 Ah battery equals 2,500 mAh.
Example Calculation 2:
Convert 0.25 Ah (small device battery) to mAh:
\[ mAh = 0.25 \times 1{,}000 = 250 \text{ mAh} \]
A 0.25 Ah battery equals 250 mAh.
Example Calculation 3:
Convert 10 Ah (laptop battery) to mAh:
\[ mAh = 10 \times 1{,}000 = 10{,}000 \text{ mAh} \]
A 10 Ah battery equals 10,000 mAh.
Quick Reference Conversion Table
This comprehensive table provides common Ah to mAh conversions for various battery capacities:
| Ampere-Hours (Ah) | Milliampere-Hours (mAh) | Typical Device |
|---|---|---|
| 0.05 Ah | 50 mAh | Small coin cell battery |
| 0.1 Ah | 100 mAh | Bluetooth earbuds (per bud) |
| 0.25 Ah | 250 mAh | Wireless mouse battery |
| 0.5 Ah | 500 mAh | Smartwatch battery |
| 1 Ah | 1,000 mAh | Small portable device |
| 2 Ah | 2,000 mAh | Budget smartphone |
| 3 Ah | 3,000 mAh | Standard smartphone |
| 5 Ah | 5,000 mAh | Flagship smartphone/Small power bank |
| 10 Ah | 10,000 mAh | Tablet/Medium power bank |
| 20 Ah | 20,000 mAh | Laptop battery/Large power bank |
What is an Ampere-Hour (Ah)?
An ampere-hour is a unit of electric charge that represents the amount of charge transferred by a steady current of one ampere flowing for one hour. It is commonly used to measure the capacity of larger batteries and energy storage systems.
Characteristics of Ampere-Hours
- Symbol: Ah (also written as A·h or A h)
- Definition: 1 Ah = 1 ampere × 1 hour = 3,600 coulombs
- Usage: Primarily for larger batteries (car batteries, solar batteries, UPS systems)
- Typical range: 1 Ah to several hundred Ah
- Status: Non-SI unit accepted for use with the SI system
Common Applications of Ah Rating
- Automotive batteries: 40-100 Ah (12V lead-acid batteries)
- Marine batteries: 50-200 Ah (deep cycle batteries)
- Solar battery banks: 100-400 Ah (off-grid systems)
- Electric vehicle batteries: 50-100 Ah per module (high voltage systems)
- UPS systems: 7-200 Ah (backup power supplies)
- Industrial equipment: Various capacities for forklifts, golf carts, etc.
Usage Guideline: Generally, batteries with capacities above 10 Ah are rated in ampere-hours (Ah), while smaller batteries below 10 Ah are often rated in milliampere-hours (mAh) for convenience.
What is a Milliampere-Hour (mAh)?
A milliampere-hour is a unit of electric charge equal to one thousandth of an ampere-hour. It is the standard unit used to rate the capacity of smaller batteries, particularly in consumer electronics and portable devices.
Characteristics of Milliampere-Hours
- Symbol: mAh
- Definition: 1 mAh = 0.001 Ah = 3.6 coulombs
- Usage: Primarily for smaller batteries in portable electronics
- Typical range: 50 mAh to 20,000 mAh
- Metric prefix: "milli-" means one thousandth (10⁻³)
Common Device Battery Capacities (mAh)
- Bluetooth earbuds: 30-100 mAh per earbud, 300-500 mAh for charging case
- Smartwatches: 200-500 mAh
- Basic smartphones: 2,000-3,000 mAh
- Flagship smartphones: 4,000-5,000 mAh
- Tablets: 6,000-12,000 mAh
- Portable power banks: 5,000-30,000 mAh
- Laptop batteries: 10,000-20,000 mAh (at internal voltage)
- E-readers: 1,000-2,000 mAh
- Digital cameras: 1,000-2,500 mAh
Why mAh for Small Batteries?
Using milliampere-hours for small batteries provides more convenient, readable numbers. For example, saying a smartphone has a "3,000 mAh battery" is more intuitive than "3 Ah battery" because it avoids small decimal values and makes comparisons easier for consumers.
Practical Applications of Ah to mAh Conversion
Understanding Ah to mAh conversion is crucial in numerous everyday and professional situations:
Consumer Electronics Shopping
- Battery comparison: Comparing batteries from different manufacturers that use different units
- Replacement batteries: Finding compatible replacements when original specifications use different units
- Power bank selection: Understanding actual capacity when comparing products
- Device runtime estimation: Calculating how long a battery will power your device
Technical Specifications
- Product documentation: Converting between units for technical manuals and datasheets
- Engineering design: Selecting appropriate battery sizes for new products
- Component sourcing: Finding batteries when suppliers list capacities in different units
- Quality control: Verifying battery specifications match across documentation
Battery Performance Analysis
- Energy density calculations: Computing energy per unit volume or weight
- Efficiency testing: Measuring actual capacity vs. rated capacity
- Degradation monitoring: Tracking capacity loss over time and charge cycles
- Cost comparison: Calculating cost per Ah or mAh for budget planning
Educational and Research
- Laboratory experiments: Standardizing measurements across different equipment
- Research papers: Reporting data in consistent units for publication
- Student projects: Understanding battery specifications and comparisons
- Science education: Teaching metric system conversions and battery technology
Reverse Conversion: mAh to Ah
Converting milliampere-hours to ampere-hours is equally simple—just divide by 1,000:
Reverse Conversion Formula:
\[ Ah = \frac{mAh}{1{,}000} \]
Or equivalently:
\[ Ah = mAh \times 0.001 \]
Reverse Conversion Examples:
Example 1: Convert 3,000 mAh to Ah:
\[ Ah = \frac{3{,}000}{1{,}000} = 3 \text{ Ah} \]
Example 2: Convert 5,000 mAh to Ah:
\[ Ah = \frac{5{,}000}{1{,}000} = 5 \text{ Ah} \]
Example 3: Convert 250 mAh to Ah:
\[ Ah = \frac{250}{1{,}000} = 0.25 \text{ Ah} \]
This reverse conversion is useful when:
- Comparing small device batteries to larger battery systems
- Converting portable device specs to match industrial battery ratings
- Calculating total system capacity when combining multiple small batteries
- Standardizing battery documentation across different product lines
Using Ah and mAh for Runtime Calculations
Battery capacity in Ah or mAh is essential for calculating how long a device will run:
Runtime Formula:
\[ \text{Runtime (hours)} = \frac{\text{Battery Capacity (mAh)}}{\text{Device Current Draw (mA)}} \]
Or using Ah:
\[ \text{Runtime (hours)} = \frac{\text{Battery Capacity (Ah)}}{\text{Device Current Draw (A)}} \]
Runtime Calculation Examples:
Example 1: Smartphone with 4,000 mAh battery, 500 mA average draw:
\[ \text{Runtime} = \frac{4{,}000}{500} = 8 \text{ hours} \]
Example 2: Flashlight with 2.5 Ah battery, 0.5 A current:
\[ \text{Runtime} = \frac{2.5}{0.5} = 5 \text{ hours} \]
Important Considerations
- Efficiency losses: Actual runtime is typically 10-20% less due to conversion losses
- Temperature effects: Cold temperatures reduce effective battery capacity
- Discharge rate: Higher current draws reduce total available capacity (Peukert effect)
- Age and condition: Older batteries deliver less capacity than their rating
- Cut-off voltage: Devices stop operating before battery is fully depleted
Common Mistakes to Avoid
When converting between Ah and mAh, watch out for these frequent errors:
- Using wrong conversion factor: Multiplying or dividing by 100 instead of 1,000
- Decimal point errors: Misplacing the decimal when converting (e.g., 2.5 Ah = 25 mAh instead of 2,500 mAh)
- Confusing with Wh: Mixing up Ah/mAh (charge) with Wh (energy)—they require voltage for conversion
- Ignoring voltage differences: Comparing batteries solely on Ah/mAh without considering voltage
- Assuming linear scaling: Thinking a 4,000 mAh battery lasts exactly twice as long as 2,000 mAh
- Not accounting for efficiency: Expecting 100% of rated capacity in real-world use
- Mixing current units: Using mA with Ah or A with mAh in runtime calculations
- Overlooking C-rate specifications: Not considering discharge rate effects on capacity
Quick Check: To verify your conversion, remember that the mAh value should always be 1,000 times larger than the Ah value. If converting 2.5 Ah, you should get 2,500 mAh (not 25 or 250).
Frequently Asked Questions (FAQs)
How many mAh are in 1 Ah?
1 ampere-hour (Ah) equals exactly 1,000 milliampere-hours (mAh). This is because the metric prefix "milli-" means one thousandth (1/1000), so 1 Ah = 1,000 mAh. This conversion factor is constant and applies to all battery capacities.
What is the formula to convert Ah to mAh?
The conversion formula is: mAh = Ah × 1,000. Simply multiply the ampere-hour value by 1,000 to get milliampere-hours. For example, 2.5 Ah × 1,000 = 2,500 mAh. This is one of the simplest unit conversions in electrical measurements.
Why do we multiply by 1,000 to convert Ah to mAh?
We multiply by 1,000 because the metric prefix "milli-" represents one thousandth of the base unit. Since 1 mAh = 0.001 Ah, then 1 Ah must equal 1,000 mAh. This follows the standard metric system convention used for all milli- prefix conversions (millimeters, milligrams, etc.).
How do you convert 2.5 Ah to mAh?
To convert 2.5 Ah to mAh: 2.5 × 1,000 = 2,500 mAh. A battery rated at 2.5 Ah has a capacity of 2,500 mAh. This is a typical capacity for modern smartphones, making it easier to understand and compare when expressed in mAh.
When should I use Ah vs mAh?
Use mAh for smaller batteries typically found in consumer electronics (smartphones, tablets, power banks) with capacities under 10 Ah. Use Ah for larger batteries (car batteries, solar systems, UPS) typically over 10 Ah. The choice makes numbers more convenient: "3,000 mAh" is easier to read than "3 Ah" for a phone, while "100 Ah" is clearer than "100,000 mAh" for a car battery.
Is a higher mAh always better?
Generally yes, higher mAh means longer battery life, but context matters. For the same voltage, higher mAh provides longer runtime. However, consider: (1) Physical size—higher capacity batteries are larger/heavier, (2) Voltage—compare Wh (Wh = V × Ah) for true energy capacity, (3) Application—excessive capacity adds unnecessary weight and cost.
Can I directly compare Ah and mAh ratings?
Yes, after converting to the same unit. A 5 Ah battery (5,000 mAh) has higher capacity than a 4,000 mAh battery (4 Ah). However, for meaningful comparison, both batteries must have the same voltage. Energy capacity (Wh) accounts for both voltage and capacity: Wh = V × Ah.
How do I convert mAh to Ah?
To convert mAh to Ah, divide by 1,000: Ah = mAh ÷ 1,000. For example, 5,000 mAh ÷ 1,000 = 5 Ah. Alternatively, multiply by 0.001: 5,000 mAh × 0.001 = 5 Ah. Both methods give the same result.
What's the difference between mAh and Wh?
mAh (milliampere-hours) measures electric charge capacity, while Wh (watt-hours) measures energy capacity. They're related by voltage: Wh = V × Ah (or V × mAh ÷ 1,000). For example, a 3.7V 3,000 mAh battery stores 3.7 × 3 = 11.1 Wh. Wh is better for comparing batteries with different voltages.
Does battery capacity decrease over time?
Yes, all rechargeable batteries lose capacity over time and charge cycles. Lithium-ion batteries typically retain 80% capacity after 300-500 full charge cycles. Factors affecting degradation include: number of charge cycles, depth of discharge, operating temperature, charging speed, and storage conditions. A 3,000 mAh battery might effectively become 2,400 mAh after 2-3 years of regular use.
Expert Tips for Ah and mAh Conversions
- Easy mental math: To convert Ah to mAh, just move the decimal point three places right (multiply by 1,000)
- For comparisons: Always convert to the same unit before comparing battery capacities
- Consider voltage: For true energy comparison, calculate Wh = V × Ah for batteries with different voltages
- Check both specifications: Quality batteries list both Ah/mAh and Wh ratings for complete information
- Understand marketing claims: Some power banks inflate mAh ratings by measuring at internal battery voltage (3.7V) rather than USB output (5V)
- Account for efficiency: Real-world usable capacity is typically 80-90% of rated capacity
- Temperature matters: Battery capacity decreases in cold temperatures; specifications are typically at 25°C
- Read the fine print: Battery capacity ratings often include conditions like "typical" vs "minimum" or specific discharge rates
Conclusion
Converting between ampere-hours (Ah) and milliampere-hours (mAh) is one of the simplest yet most practical unit conversions in battery technology. The straightforward relationship—1 Ah equals 1,000 mAh—makes it easy to translate between these units whether you're shopping for smartphone batteries, comparing power banks, or designing portable electronic devices.
Understanding that both units measure the same quantity (electric charge capacity) but at different scales helps in making informed decisions about battery selection and usage. Manufacturers choose Ah or mAh based on convenience: mAh for smaller consumer batteries to avoid small decimals, and Ah for larger batteries to avoid large numbers. The RevisionTown Ah to mAh calculator simplifies this conversion while helping you understand the fundamental relationship between these universally used battery capacity units.
Bookmark this page for quick access whenever you need to convert between Ah and mAh for battery comparisons, product specifications, or technical documentation. Master this essential conversion to confidently navigate battery ratings and make informed choices for your electronic devices and projects.
