Electronics Reference Tables — Values & Codes

One page instead of a search

You're repairing a board. A resistor reads 4R7, a capacitor reads 104, and the resistor you just calculated came out at 384 Ω. This page answers all of it — tables you open while you're still at the bench.

1. SI prefixes

The foundation everything else sits on. Get the prefix wrong and you're out by a factor of a thousand.

Prefix	Symbol	Factor	Example
pico	p	10⁻¹²	100 pF
nano	n	10⁻⁹	10 nF
micro	µ	10⁻⁶	470 µF
milli	m	10⁻³	20 mA
—	—	1	5 V
kilo	k	10³	4.7 kΩ
mega	M	10⁶	1 MΩ
giga	G	10⁹	2.4 GHz

Remember: 1 µF = 1000 nF = 1,000,000 pF. Most beginner errors live right here.

2. Preferred resistor values (E-series)

Resistors aren't made in arbitrary values — they come in standard series spaced logarithmically. Calculated 384 Ω? You won't find it. You'll buy 390 Ω.

E24 (±5 % tolerance) — the common one


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

E12 (±10 % tolerance)


1.0	1.2	1.5	1.8	2.2	2.7
3.3	3.9	4.7	5.6	6.8	8.2

E6 (±20 % tolerance)


1.0	1.5	2.2	3.3	4.7	6.8

How to read them: multiply any value by any power of ten. So 4.7 means 4.7 Ω, 47 Ω, 470 Ω, 4.7 kΩ — and so on.

Why these numbers? Because at ±5 % the tolerance bands of neighbouring values just touch without leaving a gap — whatever value you need, something covers it.

3. Resistor colour bands

Colour	Digit	Multiplier	Tolerance
Black	0	×1	—
Brown	1	×10	±1 %
Red	2	×100	±2 %
Orange	3	×1k	—
Yellow	4	×10k	—
Green	5	×100k	±0.5 %
Blue	6	×1M	±0.25 %
Violet	7	×10M	±0.1 %
Grey	8	—	±0.05 %
White	9	—	—
Gold	—	×0.1	±5 %
Silver	—	×0.01	±10 %

Read them automatically instead of memorising:

resistor-color

4. SMD resistor codes

Format	Example	Value	Rule
3-digit	`103`	10 kΩ	Two significant figures + power of ten
4-digit (1 %)	`1002`	10 kΩ	Three significant figures + power of ten
R-notation	`4R7`	4.7 Ω	The letter is the decimal point
R-notation	`R022`	0.022 Ω	Shunt / current-sense resistors
EIA-96	`01C`	10 kΩ	Two digits = value code, letter = multiplier
`0` or `000`	`000`	0 Ω	A jumper link

smd-resistor

5. Capacitor codes

Code	Value	Note
`104`	100 nF	The most common part in existence — decoupling
`103`	10 nF
`102`	1 nF
`223`	22 nF
`224`	220 nF
`105`	1 µF
`220`	22 pF	Two digits = picofarads directly
`4n7`	4.7 nF	The letter is the decimal point
`2u2`	2.2 µF

Tolerance letters

Letter	Tolerance
D	±0.5 pF
F	±1 %
J	±5 %
K	±10 %
M	±20 %
Z	+80 % / −20 %

capacitor-code

6. LED forward voltage (Vf)

Colour sets the voltage — because wavelength sets the band gap.

Colour	Typical Vf	Usual current
Red	1.8 – 2.2 V	20 mA
Yellow / orange	2.0 – 2.2 V	20 mA
Green	2.0 – 3.2 V	20 mA
Blue	3.0 – 3.4 V	20 mA
White	3.0 – 3.4 V	20 mA
Infrared	1.2 – 1.6 V	20–50 mA

led-resistor

7. Common battery voltages

Type	Nominal	Full	Empty
Alkaline (AA/AAA)	1.5 V	1.6 V	0.9 V
NiMH rechargeable	1.2 V	1.4 V	1.0 V
Li-ion (18650)	3.7 V	4.2 V	3.0 V
LiFePO4	3.2 V	3.65 V	2.5 V
Coin cell (CR2032)	3.0 V	3.3 V	2.0 V
9V battery	9 V	9.5 V	6 V
Lead-acid (cell)	2.0 V	2.15 V	1.75 V
Lead-acid (car)	12 V	12.8 V	11.8 V

Important: discharging Li-ion below 3.0 V damages it permanently. Never charge it above 4.2 V.

8. Decibel table

dB	Power ratio	Voltage ratio
0	×1	×1
3	×2	×1.41
6	×4	×2
10	×10	×3.16
20	×100	×10
40	×10,000	×100
−3	×0.5	×0.71
−6	×0.25	×0.5
−20	×0.01	×0.1

−3 dB is the definition of a filter's cutoff frequency: the point where power falls to half.

rc-filter

Key points

Preferred values exist for a reason — don't design around a value nobody sells.
104 = 100 nF, 4R7 = 4.7 Ω, 000 = a jumper.
Gold and silver in the multiplier band mean divide, not multiply.
Every table here has a matching calculator — use it instead of counting on your fingers.


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


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


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