How to Use the Current Estimation Calculator

1. Start a project

Open the calculator and click the + icon (Create a new blank project) to start from scratch, or the document icon (Start from template) to load one of the example designs below. Use the Compact / Full switch to show the full set of inputs (Full mode is part of Calculator Pro). Click the project name in the header to rename it. Your work is saved in your browser automatically, and auto-save snapshots are kept every few minutes.

2. Define operating states (Battery tab)

A state is a phase of your schedule, for example Sensing, Radio TX or Deep Sleep. Add them under Operational states in the Battery tab and give each one a duration. Pick the schedule cycle the states repeat over: a 24 h day (default), a 7-day week, or a custom length such as a 90 s wake/sleep loop. Each duration can be per cycle or per hour, day or week, so “5 s per hour” or “10 min per week” is entered directly. Mark one state (usually sleep) as fills remainder so it takes whatever time is left, and the calculator warns you if the schedule does not fit the cycle.

3. Add power rails (Rails tab)

Add a rail for every regulator output (for example 3.3 V, 5 V). Choose the regulation type: SMPS converters use their efficiency, linear regulators pass load current straight through. Enter the regulator's quiescent current per state, and nest rails under a parent rail if one regulator feeds another. Rails that are power-gated can be switched off in selected states.

4. Add loads (Loads tab)

Pick a part from the built-in library or add a custom load, assign it to a rail, and enter its current in every state. Use count for repeated parts such as multiple sensors. Resistive loads can be entered as a resistance instead of a current. If a part has short current bursts, enter its optional peak current per state so the Results tab can show a peak total.

5. Configure the power source (Battery tab)

Select a battery chemistry and capacity, or switch to an external supply. Optionally enable solar charging with a charging current and daily active hours to see whether the design is energy-positive.

6. Read the results

The Results tab shows average and peak current, per-rail and per-state breakdowns, battery life and a state-of-charge chart. Topology draws the power tree so you can sanity-check how rails and loads are connected.

7. Compare, export and share

Use the Scenario lab to clone the project and compare alternatives, export or import the project as JSON, and generate a PDF report for design reviews.

Solar-charged 3000 mAh Li-Ion system with an ESP32-S3, three BME280 sensors, two soil-moisture probes and a relay-driven fan on a boost rail.

• Multiple states: Sensing, WiFi Tx, Fan Active, Deep Sleep (fills remainder).
• Two rails: a low-IQ 3.3 V buck and a 5 V boost that is switched off outside the fan state.
• Solar input (120 mA for 6 h/day) to check the daily energy balance.

Coin-cell-class sensor node built around an nRF52832 and a BME280 that wakes, samples, advertises over BLE and sleeps.

• Short active bursts (2 s active, 100 ms TX) against a long sleep remainder.
• Why sleep current dominates battery life in low-duty-cycle designs.

ATmega328P with an analog sensor and an RFM95 LoRa radio on a single 3.3 V rail.

• Comparing radio TX energy with sensing energy.
• Using the Scenario lab to test a longer reporting interval.