E-Series Resistor Finder
Find the closest standard resistor value from E12, E24, E48, or E96 series. Get percentage error and alternatives.
Calculator
How to Use This Tool
This E-series resistor finder helps you find the closest standard resistor values to any target resistance. Standard resistor values follow E-series progressions that provide optimal coverage across the resistance range.
- Select E-Series — Choose the series based on required tolerance (E24 is most common)
- Enter Target Value — Type your calculated or desired resistance
- Select Unit — Choose Ω, kΩ, or MΩ
- Click Find Values — See the exact match or closest standard values
- Review Error — Check if the percentage error is acceptable for your design
E-Series Explained
The E-series is an international standard (IEC 60063) that defines preferred number sequences for electronic components. Each series provides values that are spaced logarithmically to ensure uniform percentage steps between adjacent values.
Available Series
| Series | Values/Decade | Tolerance | Step Ratio |
|---|---|---|---|
| E6 | 6 | ±20% | ~47% |
| E12 | 12 | ±10% | ~21% |
| E24 | 24 | ±5% | ~10% |
| E48 | 48 | ±2% | ~5% |
| E96 | 96 | ±1% | ~2.4% |
Base Values
Each series defines base values between 1.0 and 10.0. These values are then multiplied by powers of 10 to create the full range (1Ω to 10MΩ and beyond).
E24 Base Values
1.0, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.7, 3.0, 3.3, 3.6, 3.9, 4.3, 4.7, 5.1, 5.6, 6.2, 6.8, 7.5, 8.2, 9.1
Tolerance Guide
When to Use Each Tolerance
- ±20% (E6): Pull-up/pull-down resistors, LED current limiting, discharge resistors — where exact value is not critical
- ±10% (E12): General purpose applications, bias resistors, voltage dividers with moderate accuracy requirements
- ±5% (E24): Most common choice, good balance of availability and accuracy, suitable for most analog circuits
- ±2% (E48): Precision voltage dividers, feedback networks, filter circuits requiring tighter matching
- ±1% (E96): Precision applications, instrumentation, measurement circuits, precision references
Cost vs Accuracy
Tighter tolerance resistors cost more and may have longer lead times. Only specify tighter tolerances when your design actually requires them. For many applications, E24 (±5%) provides sufficient accuracy.
Practical Examples
Example 1: Calculated Voltage Divider
Your calculation requires 19.4kΩ for a voltage divider.
Target: 19.4kΩ
E24 Result: No exact match
Closest Lower: 18kΩ (-7.2%)
Closest Higher: 20kΩ (+3.1%)
Recommendation: Use 20kΩ (smaller error)
Example 2: LED Current Limiting
You calculated 165Ω for an LED at 20mA from 5V (with 1.7V forward voltage).
Target: 165Ω
E24 Result: No exact match
Closest Lower: 160Ω (higher current)
Closest Higher: 180Ω (lower current)
Recommendation: Use 180Ω (safer, LED won't be overdriven)
Example 3: Precision Reference Divider
You need exactly 4.99kΩ for a precision ADC reference circuit.
Target: 4.99kΩ
E96 Result: 4.99kΩ is an E96 value!
Match: Exact match available
Note: For precision work, use E96 (1%) resistors
Frequently Asked Questions
Why don't standard resistors come in every value?
Manufacturing resistors in every possible value would be impractical. The E-series provides values spaced so that adjacent values overlap within their tolerance bands, ensuring any desired value can be achieved with an acceptable error.
Should I choose the lower or higher value?
It depends on your application. For current limiting (LEDs, fuses), choose the higher value for safety. For pull-up resistors, either works. For voltage dividers, recalculate the actual output with each option to see which gives better results.
Can I combine resistors to get exact values?
Yes! Two resistors in series add (R1 + R2), and two in parallel give (R1 × R2)/(R1 + R2). This is useful when you need a value between standard values. However, this adds cost and board space.
What if I need a value not in any series?
Consider: (1) Using a higher precision series like E96, (2) Combining two standard resistors, (3) Using a trimmer potentiometer for adjustment, or (4) Accepting the closest standard value if the error is tolerable.
Are E-series values the same worldwide?
Yes, E-series values are defined by IEC 60063 and are internationally standardized. The same values are available from manufacturers worldwide.
Verify Your Component Selections
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