33 Ω resistor colour code
orangeorangeblackgold
33 Ω ±5%
orange orange black gold — four bands, read from the end with the bands closest to it.
| Band 1 — first digit | orange = 3 |
| Band 2 — second digit | orange = 3 |
| Band 3 — multiplier | black × 1 |
| Band 4 — tolerance | gold ± 5% |
| Value | 33 Ω |
| Acceptable range | 31.35 Ω to 34.65 Ω |
Reading it
The two digit bands give 33 and the multiplier band multiplies it by 1:
33 × 1 = 33 Ω
Which end to start from is the part that catches people. The tolerance band is the one set slightly apart from the other three, and it is gold or silver far more often than not — neither of which is a digit colour, so a gold or silver band tells you which end you are at. Read from the opposite end.
What ±5% actually means
A 33 Ω ±5% resistor is in specification anywhere from 31.35 Ω to 34.65 Ω. A meter reading of 31.35 Ω on this part is not a fault and not a reason to replace it.
33 Ω is one of the E24 values — the 24 steps per decade that ±5% resistors are made in. The steps are spaced so that the tolerance bands of neighbouring values just about touch: there is no gap between one value's range and the next, and no point making anything in between. It is the same reasoning that gives ±10% parts only 12 values per decade.
The same resistor with five bands
Precision resistors carry five bands: three digits, a multiplier and a tighter tolerance. The same 33 Ω reads
orangeorangeblackgoldbrown
— orange orange black gold brown. The digits become 3, 3 and 0, and the multiplier drops one decade to gold to compensate. The brown final band is ±1% rather than ±5%, which narrows the range to 32.67 Ω–33.33 Ω.
How much this one can take
A resistor's limit is heat, not voltage or current on their own: the power it turns into heat is V² ÷ R, so the same wattage allows very different numbers at 33 Ω than it does at a value ten times away. This is the part of a colour code lookup people actually came for and charts leave out.
| Rating | Maximum current | Maximum voltage |
|---|---|---|
| ⅛ W | 61.5 mA | 2 V |
| ¼ W | 87 mA | 2.9 V |
| ½ W | 123.1 mA | 4.1 V |
| 1 W | 174.1 mA | 5.7 V |
The quarter-watt part is the one in everybody's drawer: at 33 Ω it will carry 87 mA or stand 2.9 V across it, and not both at once — those are the same limit expressed two ways.
33 Ω is a ±10% value too
33 Ω is one of the twelve E12 values as well as one of the twenty-four E24 ones, which means it is made at ±10% and ±5% both. In practice that makes it easier to find and cheaper: E12 values are what a beginner's assortment box contains, and a shop that stocks one range stocks this value.
The nearest E12 value is 33 Ω — this one.
The same resistor as a surface-mount marking
Surface-mount resistors have no room for bands, so they carry printed digits instead — and 330 is what 33 Ω looks like on one. The scheme is the colour code with the colours replaced by the digits they stood for: two significant figures and a count of zeros.
| Marking | Used on | Reads as |
|---|---|---|
330 | Three-digit, ±5% parts | 33 with no zeros after it |
33R0 | Four-digit, ±1% parts | 33.0 Ω — the R is the decimal point |
The three-digit marking works the usual way here — 330 is 33 with nothing after it. The four-digit one cannot, because there are not three figures before the decimal point at 33 Ω, so it falls back to the R: 33R0. That is why this decade is the one where the two schemes look least alike.
Very small ±1% parts use a third scheme, EIA-96, where two digits index a table of values and a letter gives the multiplier — 01C rather than 1002. It only covers the E96 series, so it has no marking for most of the E24 values on this site, and a marking with a letter in the middle is never one of these codes.
Where 33 Ω turns up
Tens of ohms is where LED series resistors live on low-voltage rails, along with base and gate stoppers on transistors and the damping resistors on fast logic outputs. It is also the range where a resistor gets warm in normal use, so the wattage matters more here than it does higher up.
Frequently asked questions
What is the colour code for a 33 Ω resistor?
orange orange black gold on a four-band resistor: orange for 3, orange for 3, black for a multiplier of ×1, and gold for ±5%.
What resistor is orange orange black gold?
33 Ω, ±5%. The first two bands are the digits 3 and 3, the third multiplies by 1, and the gold band is the tolerance.
What is the tolerance range of a 33 Ω ±5% resistor?
31.35 Ω to 34.65 Ω. A resistor measuring anywhere in that range is within specification, which is why a meter reading of 31.35 Ω on a 33 Ω part is not a fault.
What is the five-band code for 33 Ω?
orange orange black gold brown — three digit bands (3, 3, 0), then gold as the multiplier and brown for ±1%. Five-band resistors carry an extra significant figure, so the third digit is the zero that a four-band code leaves to the multiplier.
Nearby values
- 36 Ω resistor colour code — orange blue black gold
- 39 Ω resistor colour code — orange white black gold
- 43 Ω resistor colour code — yellow orange black gold
- 47 Ω resistor colour code — yellow violet black gold
- 51 Ω resistor colour code — green brown black gold
- 56 Ω resistor colour code — green blue black gold
- 62 Ω resistor colour code — blue red black gold
- 68 Ω resistor colour code — blue grey black gold
- 75 Ω resistor colour code — violet green black gold
- 82 Ω resistor colour code — grey red black gold