The conversion between microfarads (µF), nanofarads (nF), and picofarads (pF) relies on strict factors of 1,000, while legacy "MFD" markings on HVAC capacitors are entirely identical to modern "µF". However, simply converting the units is only half the battle on the bench. The actual capacitance you get in-circuit depends heavily on the dielectric material's temperature and voltage derating characteristics. Below is the definitive reference for unit conversion, EIA part codes, and baseline thermal derating.
The Master Capacitor Conversion Chart (Units, Codes, and Derating)
How to read this table: The base value is anchored in microfarads (µF), the standard unit for bulk decoupling and motor run capacitors. We translate this to picofarads (pF) for RF/high-frequency work, nanofarads (nF) for general analog filtering, and the 3-digit EIA code printed on surface-mount and ceramic disc components. The final two columns show the maximum capacitance loss at temperature extremes compared to the 25°C baseline. These thermal limits are governed by the IEC 60384-1 and EIA-198 standards for fixed ceramic capacitors. X7R dielectrics are rated from -55°C to +125°C, while Y5V dielectrics are restricted to -30°C to +85°C.
| Base Value (µF) | Picofarads (pF) | Nanofarads (nF) | EIA 3-Digit Code | X7R Temp Loss (Max) | Y5V Temp Loss (Max) |
|---|---|---|---|---|---|
| 0.00001 µF | 10 pF | 0.01 nF | 100 | ±15% | -82% / +22% |
| 0.0001 µF | 100 pF | 0.1 nF | 101 | ±15% | -82% / +22% |
| 0.001 µF | 1,000 pF | 1 nF | 102 | ±15% | -82% / +22% |
| 0.01 µF | 10,000 pF | 10 nF | 103 | ±15% | -82% / +22% |
| 0.1 µF | 100,000 pF | 100 nF | 104 | ±15% | -82% / +22% |
| 1.0 µF | 1,000,000 pF | 1,000 nF | 105 | ±15% | -82% / +22% |
| 10.0 µF | 10,000,000 pF | 10,000 nF | 106 | ±15% | -82% / +22% |
| 100.0 µF | 100,000,000 pF | 100,000 nF | 107 | ±15% | -82% / +22% |
Bookmark-Friendly Quick-Jump Rows for Common Bench Values
When you are sorting through a mixed bin of through-hole ceramics or trying to read a faded SMD reel, these are the five most queried conversions on the bench. Bookmark this section for quick visual matching:
- The "104" Bypass Cap: 0.1 µF = 100 nF = 100,000 pF. This is the universal decoupling capacitor for 74-series logic and basic microcontroller VCC pins.
- The "103" Filter Cap: 0.01 µF = 10 nF = 10,000 pF. Standard for high-frequency analog filtering and snubber networks.
- The "105" Bulk Decoupler: 1.0 µF = 1000 nF = 1,000,000 pF. Commonly used in 0805 or 1206 SMD packages for local energy storage near ICs.
- The 4.7 µF Oddity: 4.7 µF = 4700 nF. EIA code 475. Frequently used in ESP32 and Arduino reset circuits.
- The 22 µF Workhorse: 22 µF = 22,000 nF. EIA code 226. Standard for input/output bulk filtering on 3.3V and 5V buck converters.
Decision Path: Which Column Applies to Your Installation?
Do not blindly grab a part based solely on the µF value. Use this decision tree to select the correct column and dielectric for your specific application.
| If your application is... | Then use this dielectric / column... | Concrete Part Pick (Example) |
|---|---|---|
| DC blocking, audio coupling, or general logic decoupling (under 50°C ambient) | X7R Column (±15% temp loss) | Murata GRM21BR71H105KA12 (0805, 1µF, 50V) |
| High-temperature automotive under-hood or industrial motor drive (>100°C ambient) | Upgrade to X8R or X8T (Not in table; X7R will drift) | Kemet C0805X105K8RAC (0805, 1µF, 150°C rated) |
| Cost-sensitive consumer toy, non-critical timing, strict space limits | Y5V Column (Accept -82% loss at 85°C) | Samsung CL21Y105ZBFNNNE (0805, 1µF, 50V) |
| HVAC compressor or fan motor run capacitor replacement | Ignore EIA/SMD entirely; match µF (MFD) and VAC exactly | Titan Pro 45+5 MFD, 440VAC Round Motor Run Cap |
How Derating Rows Modify the Base Value (And What the Table Cannot Tell You)
The derating rows in Table 1 modify your base value strictly based on ambient temperature. If you place a 1.0 µF Y5V capacitor in an enclosure that reaches 80°C, the dielectric physics cause the capacitance to plummet. You must calculate your worst-case scenario by taking the base value and reducing it by 82%. A 1.0 µF Y5V cap at 80°C is effectively a 0.18 µF cap. If your circuit requires a minimum of 0.5 µF to maintain a stable reset timeout, the circuit will brownout and fail.
What the table cannot tell you: This chart does not account for DC Bias Derating. This is the silent killer of modern MLCC (Multi-Layer Ceramic Capacitor) designs. As you apply DC voltage across a ceramic capacitor, the dielectric material physically stiffens, reducing its ability to store charge. For example, if you place a 10 µF X7R capacitor in a tiny 0805 SMD package and apply 25V DC across it, the effective capacitance will drop by up to 80%, leaving you with only 2 µF of actual bulk storage. To mitigate DC bias derating, you must either select a larger physical case size (like a 1210 or 2220) or choose a higher voltage rating than your circuit strictly requires. Always verify this against the manufacturer's DC bias curves, such as those provided in Murata's MLCC DC Bias FAQ.
The HVAC Motor Capacitor Myth: MFD vs. µF
A massive volume of searches for "capacitor conversion charts" come from DIYers trying to fix an air conditioner or well pump. They pull a dusty, cylindrical metal can off the motor that reads "45 MFD" and go to the hardware store, only to find modern replacements labeled "45 µF". They assume they need a mathematical conversion formula.
There is no conversion required. MFD stands for "MicroFarads" (an archaic English phonetic spelling), and µF is the modern SI symbol for the exact same unit. 45 MFD = 45 µF. When replacing motor run or start capacitors, your only conversion task is ensuring the physical dimensions fit the bracket and the voltage rating (e.g., 370VAC or 440VAC) meets or exceeds the original. Never install a lower voltage AC rating, and never use a DC-rated electrolytic capacitor in an AC motor circuit—it will vent violently. For a deeper dive into AC motor capacitor sizing and safety, refer to the All About Circuits capacitor guide.
Keep this chart at your workstation. Whether you are calculating the RC time constant for a 555 timer astable circuit or debugging a brownout on an ESP32 dev board, knowing exactly how your capacitor behaves at temperature and voltage is the difference between a prototype that works on the bench and a product that fails in the field.
