What does a 104 capacitor mean?

A 104 ceramic capacitor is 100 nF, also written 0.1 µF or 100000 pF. Read it as 10 (the first two digits) followed by 4 zeros, all in picofarads: 10 times 10 to the 4th equals 100000 pF. Divide by 1000 to get 100 nF, divide again by 1000 to get 0.1 µF. The 104 value is one of the most common decoupling capacitors on circuit boards, which is why people look it up so often.

How do I read a 3-digit capacitor code?

Take the first two digits as the significant figures and the third digit as the number of zeros to add, giving a value in picofarads. So 221 is 22 followed by 1 zero, which is 220 pF. 473 is 47 followed by 3 zeros, which is 47000 pF or 47 nF. A small value like 47 with no third digit is read literally as 47 pF. This tool shows the result in pF, nF and µF together so you never have to convert by hand.

How do pF, nF and µF relate to each other?

They step by factors of 1000. 1 µF equals 1000 nF equals 1000000 pF. So 100 nF is 0.1 µF and also 100000 pF, and 220 pF is 0.22 nF. The built-in converter lets you move a value between any two of the three units. Picofarads are used for the smallest ceramics, microfarads for larger electrolytics, and nanofarads sit comfortably in between for typical decoupling and filter parts.

What does the tolerance letter such as K or J mean?

A trailing letter encodes tolerance. J is plus or minus 5 percent, K is plus or minus 10 percent, and M is plus or minus 20 percent. So a 104K capacitor is 100 nF that may measure anywhere from 90 nF to 110 nF. Tighter grades use F for plus or minus 1 percent and G for plus or minus 2 percent. Type the letter after the code, like 104K, and the calculator shows both the value and the tolerance.

How do I find the code for a known capacitance?

Switch to the value-to-code direction, type the capacitance and pick its unit. For 100 nF the tool returns 104, for 220 pF it returns 221, for 47 nF it returns 473. It keeps two significant figures and adds the right power-of-ten digit. Values under 100 pF print as the bare number, since tiny ceramics are often marked that way rather than with a multiplier digit.

Identify a capacitor pulled from a board during repair

You desoldered a tiny ceramic part stamped 104 and need to know what to order as a replacement. Type 104 and read 100 nF / 0.1 µF instantly, then search a supplier with the value rather than guessing. The three-unit display means you match the part whether the datasheet lists it in nanofarads or microfarads.

Build a parts order from a schematic

A schematic calls for 220 pF, 1 nF and 100 nF capacitors but the BOM uses codes. Run each value through the value-to-code direction to get 221, 102 and 104, then label your storage bins and order envelopes the way the parts are actually marked. No more squinting at a chart taped to the bench.

Stock and sort a hobby electronics drawer

A grab bag of ceramics arrives marked only with codes. Decode each one to its nF value, group 103 (10 nF), 104 (100 nF) and 105 (1 µF) into labelled compartments, and you have an organized drawer you can reach into mid-project without a magnifier and a lookup table.

Teach or learn how capacitor markings work

Walking a student through why 473 is 47 nF is far clearer when the significant-figures-plus-power-of-ten rule is spelled out and the answer appears in all three units at once. Share the URL with a worked example loaded so the lesson reopens exactly where you left it.

Capacitor Code Calculator with pF nF µF Conversion

Read a 3-digit capacitor code both ways: 104 to 100 nF, or a value back to its code, with pF / nF / µF and tolerance letters, browser-only

Runs locally
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Best for Getting a realistic range before a purchase, plan, workout, or schedule decision.

Capacitor code

First two digits are significant figures; the third is how many zeros to add (the power of ten), in picofarads.

100 nF

100000

100

µF

0.1

Unit conversion

100 nF = 0.1 µF

Common codes

What this tool does

Free capacitor code calculator that decodes the 3-digit number printed on ceramic and film capacitors and works the other way too. The code 104 means 10 followed by four zeros in picofarads: 100000 pF, which is 100 nF or 0.1 µF. The first two digits are the significant figures, the third is the power of ten. Type any code such as 103, 221, 474 or 105 and read the value in all three units at once, plus the tolerance when a letter is present (104K is 100 nF at plus or minus 10 percent). Switch direction and type a capacitance with its unit to get the matching code back. A built-in pF nF µF converter and a quick-reference table of the codes people search most round it out. Everything runs in your browser with one-click copy and a shareable URL that reopens your exact lookup. 100 percent client-side, nothing is uploaded.

Tool details

Input: Numbers; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 9 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Calculator · Developer; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How Capacitor Code Calculator fits into your work

Use it for fast estimates, comparisons, and planning numbers before you make the final call.

Calculation jobs

Getting a realistic range before a purchase, plan, workout, or schedule decision.
Comparing scenarios by changing one input at a time.
Turning rough assumptions into a number you can discuss.

Calculation checks

Double-check units, dates, rates, and rounding assumptions.
Treat health, finance, tax, and legal outputs as planning aids, not professional advice.
Save the inputs that produced an important result so you can reproduce it later.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Identify a capacitor pulled from a board during repair
You desoldered a tiny ceramic part stamped 104 and need to know what to order as a replacement. Type 104 and read 100 nF / 0.1 µF instantly, then search a supplier with the value rather than guessing. The three-unit display means you match the part whether the datasheet lists it in nanofarads or microfarads.
Build a parts order from a schematic
A schematic calls for 220 pF, 1 nF and 100 nF capacitors but the BOM uses codes. Run each value through the value-to-code direction to get 221, 102 and 104, then label your storage bins and order envelopes the way the parts are actually marked. No more squinting at a chart taped to the bench.
Stock and sort a hobby electronics drawer
A grab bag of ceramics arrives marked only with codes. Decode each one to its nF value, group 103 (10 nF), 104 (100 nF) and 105 (1 µF) into labelled compartments, and you have an organized drawer you can reach into mid-project without a magnifier and a lookup table.
Teach or learn how capacitor markings work
Walking a student through why 473 is 47 nF is far clearer when the significant-figures-plus-power-of-ten rule is spelled out and the answer appears in all three units at once. Share the URL with a worked example loaded so the lesson reopens exactly where you left it.

Common pitfalls

Reading the code in nanofarads instead of picofarads. The 3-digit code always resolves to picofarads first, so 104 is 100000 pF (100 nF), not 104 nF. Convert from pF afterward; the calculator shows all three units so you never make this slip.
Confusing capacitor codes with resistor codes. They look similar but a resistor's third color band is a multiplier on ohms while a capacitor's third digit is a power of ten on picofarads. Use the resistor color code tool for resistors and this one for capacitors so the math stays right.
Treating the tolerance letter as part of the number. The trailing letter in 104K is tolerance (plus or minus 10 percent), not an extra digit. Strip it before decoding the value; this tool does that automatically and reports the tolerance separately.

Privacy

Every step here, decoding the code, encoding a value back, the pF nF µF conversion and the cheat sheet, is plain JavaScript running in your browser tab. No code, value or lookup ever leaves the page and nothing is logged. The one caveat: the shareable URL encodes your active input in the query string, so a share link pasted into chat records that input in the recipient server's access log. There is nothing sensitive about a capacitor value, but it is worth knowing how the share link works.

FAQ

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Capacitor Code Calculator with pF nF µF Conversion

Unit conversion

Common codes

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How Capacitor Code Calculator fits into your work

Calculation jobs

Calculation checks

Good next steps

Real-world use cases

Identify a capacitor pulled from a board during repair

Build a parts order from a schematic

Stock and sort a hobby electronics drawer

Teach or learn how capacitor markings work

Common pitfalls

Privacy

FAQ

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