C-Rate to Current
I = C_rate × Q
Quick answer
This calculator solves I = C_rate × Q for Current. With C-Rate 0.5, Battery Capacity 2.5 Ah, the result is 1.25 A. It solves in 3 directions, so you can enter the values you have and get the one you need.
Calculator
Formula
Description
The C-rate expresses charge or discharge current relative to the battery capacity. A 1C rate means the current that would fully charge or discharge the battery in exactly 1 hour. For a 3000 mAh battery, 1C = 3 A, 0.5C = 1.5 A (2-hour charge), and 2C = 6 A (30-minute charge). C-rate is the standard way to specify charge and discharge rates across different battery sizes, allowing direct comparison of stress levels. Higher C-rates generate more heat and accelerate degradation.
Variables
- I — Charge or discharge current (A)
- C_rate — C-rate multiplier (dimensionless, e.g., 0.5, 1, 2)
- Q — Battery capacity (Ah)
Practical Notes
Capacity units must be consistent: if Q is in Ah, I will be in A. Common charge rates: standard Li-ion charging is 0.5C-1C; fast charging is 2C-4C; some LFP cells support 5C+ continuous. Discharge ratings: typical Li-ion 1-3C continuous, RC LiPo 25-100C burst. The Peukert effect means actual deliverable capacity decreases at higher C-rates.
Symbols and units
| Symbol | Meaning | Default unit | Accepted units |
|---|---|---|---|
| I | Current | A | pA, nA, µA, mA, A, kA |
| Crate | C-Rate | — | — |
| Q | Battery Capacity | mAh | mAh, Ah |
Step by step
- 1. What you know: C-Rate 0.5, Battery Capacity 2.5 Ah
- 2. The relation: I = C_rate × Q
- 3. Substitute: Crate = 0.5, Q = 2.5 Ah
- 4. Result: Current = 1.25 A
Worked examples
Minimum range
Given: C-Rate 0.025, Battery Capacity 50 mAh
Result: Current = 1.25 mA
Low range
Given: C-Rate 0.25, Battery Capacity 0.5 Ah
Result: Current = 125 mA
Typical
Given: C-Rate 0.5, Battery Capacity 2.5 Ah
Result: Current = 1.25 A
High range
Given: C-Rate 0.8, Battery Capacity 10 Ah
Result: Current = 8 A
Maximum range
Given: C-Rate 8, Battery Capacity 100 Ah
Result: Current = 0.8 kA
Solving for each variable
Solve for Current
C-Rate 0.025, Battery Capacity 50 mAh → 1.25 mA
Solve for C-Rate
Current 2 mA, Battery Capacity 50 mAh → 0.04
Solve for Battery Capacity
Current 2 mA, C-Rate 0.025 → 80 mAh
How Current changes with C-Rate
| C-Rate (input) | Current (result) |
|---|---|
| 0.05 | 125 mA |
| 0.125 | 0.3125 A |
| 0.25 | 0.625 A |
| 0.375 | 0.9375 A |
| 0.5 | 1.25 A |
| 0.75 | 1.875 A |
| 1 | 2.5 A |
| 2 | 5 A |
| 3.5 | 8.75 A |
| 5 | 12.5 A |
The same result in other units
| Unit | Value |
|---|---|
| µA | 1250000 |
| mA | 1250 |
| A | 1.25 |
| kA | 0.00125 |
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<p><a href="https://vbatpower.com/formulas/c-rate-current/">C-Rate to Current</a> Calculator by vbatpower.com</p>Frequently asked questions
How do you calculate C-Rate to Current?
Use I = C_rate × Q. With C-Rate 0.5, Battery Capacity 2.5 Ah, Current works out to 1.25 A.
What is the formula for C-Rate to Current?
The formula is I = C_rate × Q. The C-rate expresses charge or discharge current relative to the battery capacity.
How do you find C-Rate when you know the other values?
Rearrange for C-Rate: with Current 2 mA, Battery Capacity 50 mAh, C-Rate is 0.04.
How do you find Battery Capacity when you know the other values?
Rearrange for Battery Capacity: with Current 2 mA, C-Rate 0.025, Battery Capacity is 80 mAh.
What units does C-Rate to Current use?
Current is shown in µA, mA, A, kA. Values are held in SI base units internally, so you can mix prefixes without converting by hand.
Related Concepts
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