抵抗計算機

Decode resistor color codes, calculate series and parallel resistance, and find power dissipation. Free, fast, and easy to use.

計算する

Choose a calculation type, enter your values or select color bands, and click Calculate Now to get instant results with step-by-step solutions.

完全なユーザーガイド

抵抗器とは何ですか?

A resistor is an electrical component that limits or controls the flow of electric current in a circuit. Resistance is measured in ohms (Ω) and is usually shown by colored bands on the resistor body. This tool helps you decode those color bands, combine resistors in series or parallel, and calculate power dissipation — all for free.

All Formulas at a Glance

カラーコード: R = (digits) × multiplier ± tolerance%

シリーズ: R_total = R1 + R2 + R3 + …

平行: 1/R_total = 1/R1 + 1/R2 + 1/R3 + …

力: P = V² / R  |  I = V / R

4 Calculation Types

カラーコード

抵抗器の 4 バンド、5 バンド、または 6 バンドのカラー コードから抵抗をデコードします。

直列抵抗

Calculate total resistance when resistors are connected end to end.

並列抵抗

Calculate total resistance when resistors are connected side by side.

消費電力

電圧と抵抗を使用して、抵抗器が消費する電力を求めます。

この計算機の使い方

  1. カラーコード、直列、並列、電力など、計算したいものを選択します。
  2. Enter resistor values or select color bands.
  3. 必要に応じて単位を選択します (オーム、キロオーム、メガオーム)。
  4. Click Calculate Now and see your answer with a step-by-step breakdown and chart.

Resistor Color Code Chart

• Black=0, Brown=1, Red=2, Orange=3, Yellow=4

• Green=5, Blue=6, Violet=7, Gray=8, White=9

• Gold multiplier = ×0.1, Silver multiplier = ×0.01

• 公差: ブラウン ±1%、レッド ±2%、ゴールド ±5%、シルバー ±10%

Quick Examples

• 茶-黒-赤-金 = 10 × 100 = 1000 Ω (1 kΩ) ±5%

• 2 つの 100 Ω 抵抗を直列に接続 = 200 Ω

• 2 つの 100 Ω 抵抗を並列 = 50 Ω

• 100 Ω 両端で 12 V = 1.44 W の電力損失

重要な注意事項

  • All resistance values must be greater than zero.
  • Color bands are read from left to right — the tolerance band is usually gold or silver.
  • Unit conversions are done automatically — just pick your preferred unit.
  • At least two resistors are needed for series and parallel calculations.

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