Frequently Asked Questions

How accurate are the calculators?

All calculators use industry-standard formulas from IEC, NEC, and IEEE publications. Results are computed with double-precision floating point (15+ significant digits). For most engineering applications, this exceeds practical measurement accuracy. However, always verify critical calculations against official standards and local codes.

Which standards do the calculators follow?

Our calculators reference specific international standards on each page: IEC 60364 for cable sizing, IEC 60062 for resistor color codes, NEC Article 310 for conductor sizing, IEEE Std 141 for power distribution, and IEC 60027 for letter symbols. Each calculator's educational section cites the relevant standards.

Can I use these results for official submissions?

These calculators are designed for estimation and educational purposes. While the formulas are based on international standards, official submissions (building permits, safety certifications, etc.) typically require calculations performed or verified by a licensed professional engineer. Always consult local codes and a qualified engineer.

What does the ⓘ icon mean?

Hover over the ⓘ icon next to any input field to see a brief explanation of what that parameter means and typical values. This helps you understand each input without leaving the calculator.

How do I use the unit selectors?

Some calculators (Voltage Divider, Power Calculator) have unit dropdowns next to input fields. For example, you can type "10" and select "kΩ" instead of typing "10000". The calculator automatically converts units before computing results.

What is the "Load Example Values" button?

Click this button to fill in realistic example values so you can see how the calculator works. It's a great way to learn if you're unsure what values to enter.

How does the resistor color code reverse lookup work?

Switch to "Value → Colors" mode, enter a resistance value (e.g., 4.7 kΩ), select tolerance, and the calculator will show you the correct color bands and a visual preview of the resistor.

Can I share my calculation with someone?

Yes! You can copy any result value using the "Copy" button next to each result. For a complete record, use your browser's print function (Ctrl+P) — the page is formatted for clean printing with inputs and results.

Why does my calculation show floating-point errors (like 0.30000004)?

This is a normal limitation of floating-point arithmetic in computers. Our calculators apply rounding to minimize display errors, but very small rounding artifacts may occasionally appear. For practical engineering, these differences are negligible (well below component tolerances).

Do the calculators work offline?

Once loaded, the calculators work entirely in your browser using JavaScript — no server calls are needed for calculations. If you've visited the site before, your browser cache may allow limited offline use.

Do you support SMD resistor codes?

Not yet. Our Resistor Color Code calculator currently supports through-hole resistors with 4-band and 5-band color codes. SMD resistor codes (e.g., "103" = 10 kΩ) use a different numbering system that we plan to add in a future update.

Can I use these calculators on my phone?

Yes! All calculators are fully responsive and work on any screen size. On smaller screens, the input and output panels stack vertically for easy scrolling.

Is CoreCalx really free?

Yes, all calculators are 100% free with no account required. We cover costs through non-intrusive advertising. There are no premium tiers or hidden fees.

Will you add more calculators?

We're actively developing new calculators. Planned additions include LED resistor calculators, PCB trace width calculators, and more. Check back regularly or visit our blog for updates.

How can I report a bug or suggest a feature?

We'd love to hear from you! Visit our Contact page to send us feedback, bug reports, or feature requests.