ESP32 Battery Life Estimator

Calculator

All fields update the estimate live. Pick a preset below to auto-fill sleep current.

Active current draw

mA

Wi-Fi/BLE active, sensors reading, CPU awake — typically 80–260 mA. Enter a value greater than 0.

Active duration per wake

How long the chip stays fully awake each time it wakes up. Enter a value greater than 0.

Deep sleep current

mA

Chip in deep sleep — typically 0.01–0.15 mA depending on RTC peripherals kept on. Enter a value 0 or greater.

Wake interval

How often the ESP32 wakes from deep sleep to do something. Enter a value greater than 0.

Battery capacity

mAh

Rated capacity of your battery, e.g. a typical 18650 cell is ~2000–3500 mAh. Enter a value greater than 0.

Usable capacity

%

Accounts for self-discharge, regulator/LDO losses, and voltage cutoff before the rated capacity is fully used. Enter a whole number from 1 to 100.

Average current draw

—

Estimated battery life

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Wake-ups per day

—

Active current draw — 0% Deep sleep draw — 0%

Share of total energy consumed by each state — not share of time, since the active state usually draws 1,000×+ more current than deep sleep even though it lasts a tiny fraction of the cycle.

Deep sleep current presets

Typical ESP32 deep sleep current for common RTC peripheral configurations. Click to fill the "deep sleep current" field above.

Quick scenarios

Populate the whole form with a common project pattern.

About this tool

Why ESP32 battery life is hard to estimate

The ESP32 spends most of its life in one of two very different power states: briefly awake and drawing tens to hundreds of milliamps while it does real work, then deeply asleep and drawing a few microamps until the next wake-up. A back-of-envelope estimate using just one of those numbers is almost always wrong — the real battery life depends on the weighted average of both, based on how long each phase actually lasts.

What this calculator does

You enter the active current draw and how long each wake stays active, the deep sleep current, how often the chip wakes up, and your battery's capacity. It computes the time-weighted average current across a full wake/sleep cycle, then divides your usable battery capacity by that average to estimate total runtime in hours and days — plus a chart showing what share of total energy the active phase actually consumes.

Why it's useful

It turns "how long will this run on a battery" from a guess into a number you can act on before you commit to a battery size or a wake interval — and it usually reveals that shortening the active phase matters far more for battery life than tweaking the deep sleep current, since active current is often 1,000–10,000× higher.

Who should use it

Anyone building a battery-powered ESP32 project — sensor nodes, BLE beacons, remote monitors — who needs to size a battery or decide whether a wake interval is realistic before building the hardware.

A note on accuracy

This is a straight-line average-current model — it doesn't account for the brief current spikes during Wi-Fi/BLE radio bursts, boost-converter inefficiency, or battery voltage sag under load, all of which can shorten real-world runtime versus this estimate. Treat the result as an optimistic upper bound and validate with a real current-measurement test before finalizing a battery-powered design.