Calculate the correct series resistor needed to safely power light-emitting diodes. Input supply voltage, LED voltage drop, current, and the number of LEDs to find the required resistor value and wattage.


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| # | App | Price | Rating | Ads | In-App Purchases | Updated | |
|---|---|---|---|---|---|---|---|
| 1 | Free | — | No | No | May 2026 | ||
| 2 | $2.99 | 4.8★ (8) | No | No | Sep 2026 | ||
| 3 | Free | 4.9★ (34K) | Yes | Yes | Sep 2026 | ||
| 4 | Free | 4.7★ (1.7M) | Yes | Yes | Sep 2026 | ||
| 5 | Free | 4.5★ (126K) | Yes | Yes | Sep 2026 | ||
| 6 | Free | 5.0★ (1) | No | No | Aug 2026 | ||
| 7 | Free | 4.7★ (16K) | Yes | Yes | Sep 2026 | ||
| 8 | Free | 4.7★ (25K) | No | Yes | Sep 2026 |








Calculate the correct series resistor needed to safely power light-emitting diodes. Input supply voltage, LED voltage drop, current, and the number of LEDs to find the required resistor value and wattage.





This app offers a straightforward calculation experience, focusing on essential functions without unnecessary complexity. It includes basic arithmetic, percentage calculations, and advanced functions like square root. Users can customize the appearance with multiple color schemes and utilize features like result copying and split-screen multitasking on iPad.