1 kΩ and 2 kΩ: the classic
- Input
- 5V 1k 2k
- Expected output
- 3.33V
1% above target, 1.67 mA.
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5v to 3.3v voltage divider
It is the most common level conversion between 5 V boards and 3.3 V devices: a data line that must arrive lower on the other side. For a signal that only goes one way, two resistors are enough. The tool opens in search mode with 5 V in and 3.3 V out, shows the E24 pairs grouped by total resistance, and lets you enter the load of the input that will be connected.
1% above target, 1.67 mA.
−0.09%, 3.62 mA.
Same ratio, 0.36 mA.
−0.10%, 2.75 mA.
Ratio 0.5, only 0.17 mA.
The load lowers the output by 6%.
Vout = Vin × R2 ÷ (R1 + R2), with R1 between the input and the output and R2 between the output and ground. For 5 V with R1 = 1 kΩ and R2 = 2 kΩ, Vout = 5 × 2000 ÷ 3000 = 3.33 V.
Use a divider with R1 ÷ R2 = 0.515, such as 470 Ω and 910 Ω (3.297 V) or 1 kΩ and 2 kΩ (3.333 V). Connect R1 to the 5 V side and R2 to ground, and take the output between them.
They give 3.333 V, about 1% above 3.3 V, which is acceptable for most logic inputs. For more accuracy, 470 Ω and 910 Ω give 3.297 V.
With care. Large resistors plus the input capacitance form a filter that delays the edges. For fast signals, use smaller values or a purpose-built level shifter.
No. A divider only reduces voltage. To go up you need a level shifter, a transistor or a dedicated integrated circuit.
R1 + R2 between 100 Ω and 1 kΩ
| R1 | R2 | Vout | Error | Current | Use |
|---|---|---|---|---|---|
| 200 Ω | 390 Ω | 3.305 V | +0.15% | 8.47 mA | |
| 220 Ω | 430 Ω | 3.308 V | +0.23% | 7.69 mA | |
| 240 Ω | 470 Ω | 3.31 V | +0.30% | 7.04 mA |
R1 + R2 between 1 kΩ and 10 kΩ
| R1 | R2 | Vout | Error | Current | Use |
|---|---|---|---|---|---|
| 470 Ω | 910 Ω | 3.297 V | −0.09% | 3.62 mA | |
| 620 Ω | 1.2 kΩ | 3.297 V | −0.10% | 2.75 mA | |
| 2 kΩ | 3.9 kΩ | 3.305 V | +0.15% | 847 µA |
R1 + R2 between 10 kΩ and 100 kΩ
| R1 | R2 | Vout | Error | Current | Use |
|---|---|---|---|---|---|
| 4.7 kΩ | 9.1 kΩ | 3.297 V | −0.09% | 362 µA | |
| 6.2 kΩ | 12 kΩ | 3.297 V | −0.10% | 275 µA | |
| 20 kΩ | 39 kΩ | 3.305 V | +0.15% | 84.7 µA |
R1 + R2 between 100 kΩ and 1 MΩ
| R1 | R2 | Vout | Error | Current | Use |
|---|---|---|---|---|---|
| 47 kΩ | 91 kΩ | 3.297 V | −0.09% | 36.2 µA | |
| 62 kΩ | 120 kΩ | 3.297 V | −0.10% | 27.5 µA | |
| 200 kΩ | 390 kΩ | 3.305 V | +0.15% | 8.47 µA |
R1 + R2 between 1 MΩ and 10 MΩ
| R1 | R2 | Vout | Error | Current | Use |
|---|---|---|---|---|---|
| 470 kΩ | 910 kΩ | 3.297 V | −0.09% | 3.62 µA | |
| 390 kΩ | 750 kΩ | 3.289 V | −0.32% | 4.39 µA | |
| 510 kΩ | 1 MΩ | 3.311 V | +0.34% | 3.31 µA |
One group per range of total resistance. A low sum wastes current, a high sum lets the load pull the output down. The error is only series rounding; add the resistor tolerance on top.
The math runs in your browser; no value is sent to a server. A resistive divider is for signals and references, not for powering circuits that draw current.