Standard resistor values, called E-Series values, are preferred resistance numbers used worldwide. They are arranged in steady steps across decade ranges like 10Ω–100Ω and 100Ω–1kΩ, so common values stay consistent and easy to find. This article explains E-Series groups, decade ranges, tolerance matching, and value spacing, with detailed coverage from E3 to E192.
Standard Resistor Values (E-Series) Basics
Standard resistor values, also called E-Series values, are a set of preferred resistance numbers used worldwide. These values follow a planned pattern that spreads resistance steps evenly across each decade range (such as 10Ω–100Ω, then 100Ω–1kΩ).
Instead of producing every possible resistance number, standard lists ensure that values remain consistent, available, and easy to replace.
E-Series Numbering System and Decade Ranges
The E-Series groups standard resistor values into sets such as E3, E6, E12, E24, E48, E96, and E192. The number shows how many standard values exist per decade, meaning a range that grows by ×10. Common decade ranges include:
• 1Ω to 10Ω
• 10Ω to 100Ω
• 100Ω to 1kΩ
• 1kΩ to 10kΩ
How does Resistor Tolerance Match Each E-Series?
| E-Series | Typical Tolerance |
|---|---|
| E3 | ±40% |
| E6 | ±20% |
| E12 | ±10% |
| E24 | ±5% |
| E48 | ±2% |
| E96 | ±1% |
| E192 | ≤±0.5% |
E3 Series: Basic Values With Wide Spacing
• Values per decade: 1.0, 2.2, 4.7
• Repeats across: 10Ω, 22Ω, 47Ω
• Scales up to: 100Ω, 220Ω, 470Ω → 1kΩ, 2.2kΩ, 4.7kΩ
E6 Series: Simple Set With Smaller Gaps
• Values per decade: 1.0, 1.5, 2.2, 3.3, 4.7, 6.8
• Repeats across: 10Ω, 15Ω, 22Ω, 33Ω, 47Ω, 68Ω
• Scales up by: ×10 each decade (100Ω, 150Ω, 220Ω...)
E12 Series: Common Standard Values
• Values per decade:
| - | Values |
|---|---|
| 1 | 1.0, 1.2, 1.5, 1.8 |
| 2 | 2.2, 2.7, 3.3, 3.9 |
| 3 | 4.7, 5.6, 6.8, 8.2 |
• Repeats across decades by ×10
• Fits 10%, 5%, and some 2% tolerance resistors
E24 Series: More Options for Closer Target Values
The E24 series has 24 values per decade. It provides smaller steps between values than E12, making it more suitable for circuits that require mid-level precision.
• Values per decade:
| Row | Values |
|---|---|
| 1 | 1.0, 1.1, 1.2, 1.3 |
| 2 | 1.5, 1.6, 1.8, 2.0 |
| 3 | 2.2, 2.4, 2.7, 3.0 |
| 4 | 3.3, 3.6, 3.9, 4.3 |
| 5 | 4.7, 5.1, 5.6, 6.2 |
| 6 | 6.8, 7.5, 8.2, 9.1 |
• Repeats every decade by ×10
• Fits 5% and some 2% tolerance resistors
E48 Series: Smaller Steps for More Accurate Values
The E48 series provides 48 standard resistor values per decade, resulting in smaller steps between values.
• 48 values per decade for tighter spacing
• Smaller gaps between resistor choices
• Values repeat every decade by ×10
E96 Series: Tight Value Steps for High-Precision Circuits
• 96 values per decade
• Very small steps between values
• Used in precise and calibrated circuits
• Values repeat every decade by ×10
E192 Series: Ultra-Precision Standard Values
• 192 values per decade
• Used in lab tools and calibrated systems
• Very tight tolerance, down to ±0.1%
• Values repeat by ×10 each decade
Why E-Series Values Use Logarithmic Spacing?
Standard resistor values are calculated using logarithmic spacing, meaning each step increases by a consistent ratio rather than a fixed amount. This keeps the spacing balanced across every decade. A common formula is:
10^(1/N)
• N = number of values per decade
• Smaller N = wider spacing
• Larger N = finer spacing
Choosing the Right Standard Resistor E-Series
| Required Accuracy Level | Recommended E-Series |
|---|---|
| Low Accuracy | E6 / E12 |
| General Purpose | E12 / E24 |
| Tighter Selection | E24 / E48 |
| Precision Selection | E96 |
| Ultra Precision | E192 |
Conclusion
The E-Series organizes resistor values into sets like E3, E6, E12, E24, E48, E96, and E192, based on how many values fit in each decade. Each series matches a typical tolerance level, from wider steps to very tight precision. The values follow logarithmic spacing, using a constant ratio step of 10^(1/N) across decades.
Frequently Asked Questions [FAQ]
What do I do if my exact resistor value isn’t available?
Choose the nearest standard value or combine resistors in series or parallel.
What do k and M mean on resistor values?
k = ×1,000 and M = ×1,000,000.
Do E-Series values apply to both SMD and through-hole resistors?
Yes. E-Series values apply to both types.
Can a 1% resistor still use E24 values?
Yes. Some 1% resistors are sold in E24-style values for availability.
What is the difference between resistance and power rating?
Resistance (Ω) controls current. Power rating (W) tells how much heat it can handle.
Are E-Series values exact or rounded?
They are rounded standard values based on logarithmic spacing.
