What next?
Decoding the bands is the first step. These are the calculations that usually follow once you know the value.
The colour code gained a new colour in 2016
Almost every resistor chart online shows twelve colours. The current standard has thirteen: the 2016 edition of IEC 60062 added pink as a multiplier meaning ×10⁻³, for the very low-value current-sense resistors that barely existed when the code was written. If a chart has no pink, it predates 2016.
The other overlooked rule is about which end you start from. The standard says the tolerance band should be 1.5 to 2 times wider than the others precisely so you can tell. In practice the gap before it is the giveaway, and gold or silver in the last position is almost always tolerance rather than a digit.
This calculator only offers the colours that are legal for the band you are editing, so you cannot build a resistor that could not exist — there is no yellow tolerance band, and no gold significant digit.
What your result means
The large figure is the nominal resistance — what the part is sold as. The tolerance below it is the manufacturer’s guarantee, and the minimum and maximum are what the resistor may actually measure. A ±5% 4.7 kΩ part measuring 4.55 kΩ is not faulty; it is in spec.
The shorthand code is the same value written the way it appears on schematics and in parts lists — 4K7 rather than 4.7 kΩ, R22 rather than 0.22 Ω. The letter replaces the decimal point, because a printed dot is easy to lose.
Once you have the value, the series and parallel resistance calculator reduces a whole network to the single figure Ohm’s law needs. The panel at the bottom is the sanity check. Resistors are only made in the E-series of preferred values, so if your decoded value belongs to no series at all, you have almost certainly read the bands from the wrong end or misjudged a colour under poor light.
Why this one is different
Tolerance is turned into the window it means — the lowest and highest resistance the band actually permits — rather than being printed as a percentage to work out yourself. The shorthand code stamped on surface-mount parts is given alongside, and the temperature coefficient band, where the resistor has one, is translated into drift per degree.
How it works
Each band has one job, and the job depends on how many bands the resistor has. The first bands are significant digits, the next is a power-of-ten multiplier, and the last one or two describe the part’s quality rather than its value.
None of the bands describe the power rating, so size the part with the power dissipation calculator before you fit it. The fifth band on a five-band part and the sixth on a six-band part are easy to confuse. The tolerance band sits after a visible gap; the temperature coefficient is the one beyond it, and it is only present on precision parts.
How to use this calculator
- Count the bands on your resistor and pick 4, 5 or 6.
- Hold the resistor so the wider band, or the one after the gap, is on the right.
- Click a band on the diagram to select it, then choose its colour from the swatches below.
- Read the resistance, tolerance and measured range on the right.
- Check the panel at the bottom — if it says the value is not standard, try reading the bands the other way round.
Formula
D is the significant digits read in order (two bands on a 4-band part, three on a 5 or 6-band part). M is the multiplier band’s exponent — black is 0, brown 1, red 2 and so on, with gold −1, silver −2 and pink −3. The tolerance band gives the percentage the real value may differ by, and does not affect R itself.
Example calculation
A 4-band resistor banded yellow, violet, red, gold:
Red multiplier → ×10² = ×100
R = 47 × 100 = 4.7 kΩ
Gold → ±5% → 4.46 kΩ to 4.93 kΩ
Shorthand = 4K7 · 47 is an E6 value, so this is a stocked part
Frequently asked questions
Which end of the resistor do I start reading from?＋
Start at the end whose first band is closest to the lead. The tolerance band is at the other end, is often separated by a wider gap, and on cheap parts is gold or silver — neither of which is ever a significant digit. If the value you get is not a standard E-series value, you are almost certainly reading it backwards.
Why does my multimeter disagree with the bands?＋
Within the tolerance, disagreement is normal and not a fault: a 10% 100 ohm resistor may legitimately measure anywhere from 90 to 110 ohms. Larger discrepancies usually mean the resistor is still in circuit and you are measuring it in parallel with everything around it, or that the part has been overheated.
What does the sixth band mean?＋
It is the temperature coefficient in parts per million per kelvin — how much the resistance drifts as the part warms. Brown is 100 ppm/K, red 50 and blue 10. It only matters in precision analogue work; for hobby circuits the value and tolerance are what count.
Assumptions & limitations
This tool reads the marking and nothing else. Keep these limits in mind:
- It decodes value and tolerance only. The bands carry no information about power rating or working voltage — those come from the resistor’s physical size and its datasheet, and using an underrated part is how resistors burn.
- A resistor measured in circuit reads low, because your meter sees it in parallel with every other path around it. Desolder one leg before comparing a measurement with the figure here.
- The E-series check rounds to a three-digit mantissa. Genuine non-preferred values do exist in precision and current-sense parts, so “not a standard value” means “check your reading first”, not “this resistor cannot exist”.
- The temperature-coefficient list only offers the colours IEC 60062 assigns a TCR to. Manufacturers occasionally use their own sixth-band conventions, and a few use it for reliability class instead — the datasheet wins.
- Colours fade and char with age and heat. Brown, red and orange are the usual casualties under poor light, and a scorched resistor has often drifted well outside tolerance anyway. When the decoded value looks implausible, check the part against a known current with the Ohm’s law calculator rather than trusting the bands.