MCU Power Consumption
Estimate microcontroller battery life in active and sleep modes. Enter circuit values to calculate the selected electrical quantity.
Current Consumption
Battery
Electronics guide · Electrical power, energy, and wiring
About MCU Power Consumption Calculator
Estimate average current and optional battery life for a microcontroller that alternates between active and sleep states. The form uses current in each state, active duty cycle, supply voltage, circuit efficiency, and optional battery capacity.
Power and energy calculations relate quantities such as voltage, current, resistance, time, and load. AC and DC systems can require different assumptions, and a calculated estimate is not a substitute for checking source capability, wire ratings, protection, efficiency, and equipment specifications.
How to Use This Tool
- 1.Enter active current in mA, sleep current in µA, active duty percentage, and supply voltage.
- 2.For runtime, add battery capacity in mAh and circuit efficiency as a percentage.
- 3.Calculate and inspect average current, average power, and estimated battery life if a capacity was supplied.
Technical Details to Check
1.Check AC or DC assumptions
In AC calculations, voltage and current may refer to RMS values, and phase relationships can affect real power. Do not apply a DC relationship to an AC system unless the tool's stated assumptions fit.
2.Power is not the same as energy
Watts describe a rate of energy use; watt-hours and joules describe an amount of energy over time. A runtime or consumption estimate needs both a load and a duration or duty profile.
3.Real systems lose energy
Inverters, batteries, wiring, motors, and power supplies are not perfectly efficient. Confirm whether the selected calculation includes efficiency, power factor, voltage drop, or only ideal values.
4.Ratings and protection are essential
An estimated current or power value does not determine a safe wire size, fuse, battery connection, or supply. Follow applicable standards, product ratings, and qualified design guidance.
How the Calculation Works
The calculator weights active and sleep currents by their time shares, converts µA to mA, then adjusts average current for the entered efficiency. Average power uses voltage and adjusted current. Estimated runtime divides usable battery capacity by average adjusted current, assuming the duty cycle and load stay constant.
Worked Example
A device spending only a small fraction of time active can have an average current far below its active-state current, though radio bursts and peripherals may dominate in practice.
Where This Tool Can Help
Compare low-power firmware duty cycles and make an initial battery-runtime estimate for an MCU-based design.
Estimating a load
Use known voltage and current or power figures to understand a device's approximate demand before checking its label and startup behavior.
Planning energy use
Combine a power estimate with realistic operating hours to compare possible consumption, while accounting separately for standby use and efficiency.
Checking a wiring estimate
Use current or voltage-drop results as an early check, then verify conductor size and protection with the correct installation rules and environment.
Comparing supply options
Compare candidate sources on the same voltage, current, power, and duration basis, and include headroom where the equipment specification requires it.
Tips for More Reliable Results
- Confirm whether voltage and current are RMS, peak, nominal, or measured under load.
- Keep watts, watt-hours, joules, and time units distinct when entering values.
- Include efficiency or power factor only when the tool provides that input and you have a suitable value.
- Check conductor, connector, battery, and supply ratings before using an estimate in a real installation.
Limitations and Assumptions
Real current varies with clock, peripheral state, radio transmission, regulator quiescent draw, battery voltage, temperature, and firmware behavior. The tool assumes a stable duty cycle. Measure the assembled device over representative workloads before choosing a battery.
Electrical power tools estimate values from entered figures and stated assumptions. They do not measure a circuit, model every transient or loss, or certify wiring and equipment as safe. Confirm important designs with manufacturer data and applicable electrical requirements.
Frequently Asked Questions
Why does sleep current matter?
A device may spend most of its time asleep, so even small sleep draw contributes to average consumption.
Does battery life use the efficiency field?
Yes, the page adjusts the average current using the entered circuit-efficiency assumption.
Is the result a guaranteed runtime?
No. It assumes constant state currents, duty cycle, and usable battery capacity.
Are watts and watt-hours interchangeable?
No. Watts are a rate; watt-hours measure energy used over time.
Does a calculated value make a circuit safe to build?
No. Safety depends on ratings, protection, installation conditions, and applicable standards as well as the arithmetic.