Free · Open Source · No Sign-up

Free Online Electronics
Calculators & Tools

17 professional-grade electronics calculators — Ohm's Law, resistor color codes, voltage dividers, LED resistors, wire gauges, inverter sizing, and more. Instant results, always free.

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Runs entirely in your browser — no server, no accountAll formulas verified against IEEE and IEC standardsFree forever — no paywalls or usage limitsWorks on desktop, tablet, and mobile

Calculator Suite

All 17 Tools

Popular

Fundamentals

Ohm's Law Calculator

Calculate voltage, current, or resistance instantly using Ohm's Law. Essential for every electronics project.

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Power & Battery

Inverter & Battery Calculator

Size your inverter (VA) and battery bank (Ah) for solar, off-grid, and backup power systems.

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Components

Resistor Color Code Calculator

Decode 4-band and 5-band resistor color codes to get exact resistance and tolerance values.

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Components

SMD Resistor Code Decoder

Decode EIA-96 and 3/4-digit SMD resistor markings to resistance values.

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Components

Capacitor Code Calculator

Convert 3-digit capacitor codes to pF, nF, and µF values with tolerance info.

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Wire & Cable

AWG Wire Gauge Calculator

Look up wire diameter, cross-section area, and max current capacity by AWG number.

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Wire & Cable

SWG Wire Gauge Calculator

Convert SWG numbers to wire dimensions. Standard for Indian and British wiring.

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Fundamentals

Star-Delta Conversion

Convert between Star (Y) and Delta (Δ) resistor networks for three-phase AC circuits.

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New

Fundamentals

Voltage Divider Calculator

Calculate output voltage, required resistor values, or input voltage for resistor divider circuits.

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Components

LED Series Resistor Calculator

Find the correct current-limiting resistor value and wattage for single or series LEDs.

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New

Fundamentals

Pull-up / Pull-down Resistor

Calculate optimal pull-up or pull-down resistor values, valid ranges, and power for digital logic.

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Power & Battery

Battery Backup Time

Calculate how long your inverter battery will last based on Ah capacity, load, voltage, and efficiency.

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Power & Battery

Battery Charging Time

Estimate charging time for your inverter or solar battery based on charger current and DoD.

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New

Power & Battery

Inverter Battery Matching

Find the right inverter VA and battery Ah for your home load and desired backup hours.

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Power & Battery

DC Load Calculator

Add up DC appliances to find total watts and amps for 12V, 24V, or 48V off-grid systems.

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Power & Battery

AC Load Calculator

Calculate total power, monthly kWh, and estimated electricity cost for household appliances.

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Power & Battery

Solar Load Calculator

Size your solar panels, battery bank, charge controller, and inverter for your daily load.

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Why ElectroCalc

Built for professionals,
free for everyone.

ElectroCalc is a free suite of electronics engineering tools built and maintained by KSP Electronics. Every calculator follows IEEE and IEC standards so you can trust the results in real-world projects — from student labs to production engineering.

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Browser-based

All calculations run locally in your browser. No data is ever sent to a server.

IEEE & IEC verified

Every formula is sourced from recognised international standards.

Free, no account required

Unlimited use with zero sign-ups — no ads on calculator pages.

Open Source

The full source code is available on GitHub for transparency and contributions.

FAQ

Frequently Asked Questions

What is ElectroCalc?

ElectroCalc is a free suite of online electronics calculators built by KSP Electronics. It includes tools for Ohm's Law, resistor color codes, voltage dividers, LED resistor calculations, wire gauge lookups, inverter/battery sizing, and more.

Are these electronics calculators really free?

Yes, 100% free with no sign-up required. All calculators run entirely in your browser — no data is ever sent to any server. There are no paywalls, usage limits, or hidden charges.

How accurate are the calculations?

All formulas are verified against IEEE and IEC standards. Results are computed locally using double-precision floating-point arithmetic for maximum accuracy. We recommend verifying critical designs against component datasheets.

What is a voltage divider calculator used for?

A voltage divider calculator helps you determine the output voltage of a resistor divider network, or find the resistor values needed to achieve a specific voltage. Common uses include level shifting (e.g., 5V to 3.3V), ADC reference voltage scaling, and sensor signal conditioning.

How do I calculate the resistor for an LED?

Use the LED Series Resistor Calculator. Enter your supply voltage, the LED's forward voltage (Vf) and forward current (If), and the number of LEDs in series. The calculator gives you the exact resistor value, the nearest standard E24 value, and the recommended wattage rating.

What is the difference between kspelectronics.in and tools.kspelectronics.in?

kspelectronics.in is our main e-commerce store where you can purchase electronic components, development boards, sensors, and project kits. tools.kspelectronics.in (ElectroCalc) is our free engineering tools and calculators platform for electronics professionals and students.

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Need components for your project? Visit our e-commerce store for development boards, sensors, resistors, capacitors, and project kits.

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