Resistor finder
Finds the nearest resistor to a desired value from the standard "E" families. Resistors are commonly available from 10Ω to 1MΩ, values above and below this range are harder to find. Resistors are readily available as metal film chip resistors in surface mount packages (402, 603, 805, 1206) and leaded axial packages. These parts have fractional power capability. Resistors with larger power capability are less readily available. Ceramic capacitors in 5% and 10% tolerance follow the E24 and E12 rules. They are commonly available from 10pF to 1u. It can be prudent to stick to the E12 values: 1, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, and 8.2 when selecting capacitors. |
Resistor divider
Select the variable you wish to find, fill in the other values, and click "Calculate". |
Resistors in parallel
Select the variable you wish to find, fill in the other values, and click "Calculate". |
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This applet finds the time constant and corner frequency for a simple RC circuit. |
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This is a guideline chart for picking the right size SMD resistor for power dissipation. |
Size |
Size Metric |
Length (in) |
Width (in) |
Length (mm) |
Width (mm) |
Height (mm) |
Watts |
Max Operating Voltage (V) |
No Margin Resistance for 3.3V Power Dissipation (Ohms) |
| 0201 | 0603 | 0.02 | 0.01 | 0.60 | 0.30 | 0.25 | 0.05 | 25 | 218 |
| 0402 | 1005 | 0.04 | 0.02 | 1.00 | 0.50 | 0.35 | 0.06 | 50 | 182 |
| 0603 | 1608 | 0.06 | 0.03 | 1.55 | 0.80 | 0.50 | 0.1 | 75 | 109 |
| 0805 | 2012 | 0.08 | 0.05 | 2.00 | 1.25 | 0.50 | 0.125 | 150 | 87 |
| 1206 | 3216 | 0.12 | 0.06 | 3.20 | 1.60 | 0.60 | 0.25 | 200 | 44 |
| 1210 | 3225 | 0.12 | 0.10 | 3.20 | 2.60 | 0.50 | 0.5 | 200 | 22 |
| 1218 | 3246 | 0.12 | 0.18 | 3.10 | 4.60 | 0.90 | 1.0 | 200 | 11 |
| 2010 | 5025 | 0.20 | 0.10 | 5.00 | 2.60 | 0.70 | 0.75 | 200 | 15 |
| 2512 | 6432 | 0.25 | 0.12 | 6.30 | 3.20 | 0.60 | 1.0 | 250 | 11 |
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