HOW-TO GUIDE
How to Measure Microamps With a Multimeter
By the OhmSavvy Research Team ·
Milliamps vs. microamps: not just a smaller number
A microamp is one-thousandth of a milliamp. That scale difference matters practically: at microamp levels, tiny sources of error that are completely irrelevant on the mA range — stray leakage paths, meter burden voltage, even static charge on test leads — become large enough relative to the signal to meaningfully affect the reading. Setup and technique that work fine for milliamp measurements need extra care here.
Where microamp currents actually show up
Coin-cell self-discharge
A CR2032's own datasheet puts self-discharge at roughly 1–3% of capacity per year, which works out to hundreds of nanoamps to a few microamps of continuous draw.
Op-amp input bias current
Usually nanoamps or even picoamps, not microamps — TI's datasheet for the bipolar-input LM358 gives a typical -20 nA, and Diodes Inc.'s datasheet for the JFET-input TL072 gives a typical 65 pA. µA-level bias current only shows up on older or unusually leaky parts.
Photodiode dark current
Current flowing with no light present, typically a few µA or less.
Sleep-mode microcontroller draw
Modern low-power MCUs can idle at single-digit µA in deep sleep.
Worked example: a CR2032 rated 230 mAh losing roughly 2% of its capacity a year to self-discharge is losing about 4.6 mAh annually (230 mAh × 0.02). Spread that loss evenly across the 8,760 hours in a year, 4.6 mAh ÷ 8,760 h, and the average continuous current is about 0.53 µA — comfortably inside a dedicated µA range, and far too small for the mA range to resolve at all. Manufacturer self-discharge figures vary (roughly 1–3% per year depending on the cell and datasheet), so treat 0.53 µA as an illustrative midpoint, not a spec for any specific battery.
1Measuring microamps step by step
Power down the circuit, break the path where you want to measure current, and connect the meter in series in that gap — the same fundamental setup as any current measurement. Select the µA range on the dial (not mA or A), power the circuit back up, and read the display once it settles.
Sources of error specific to this range
| Source of error | Why it matters at µA levels |
|---|---|
| Meter burden voltage | The meter's own tiny internal resistance causes a voltage drop that can disturb a sensitive circuit |
| Stray leakage paths | Dirt, flux residue, or humidity on a board can leak enough current to be comparable to the signal itself |
| Test lead capacitance | Can cause a slow settling drift before the reading stabilizes |
| Electrical noise pickup | Test leads can act as small antennas; at µA levels, picked-up noise currents are no longer negligible |
Keep the leads short and the circuit clean
Quick reference
A µA range on a real meter looks like this: the Fluke 116's own spec sheet lists 600.0 µA AC/DC with 0.1 µA resolution, so a meter in this class can resolve a change as small as a tenth of a microamp. Not every multimeter has this range at all — check the model's own spec sheet rather than assuming, since it is a feature some otherwise-similar meters in the same product family leave out.
Same core technique as milliamps — series connection, correct range, fuse-protected current jack — with extra attention paid to settling time, lead length, and board cleanliness. See our milliamps guide for the base technique this builds on.
In short
Meters with a dedicated µA range
600.0 µA AC/DC range at 0.1 µA resolution, built for flame-sensor checks.
A clamp meter with its own 200 µA DC range (0.1 µA resolution) through the test leads.
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Frequently asked questions
Can I use the same jack as milliamps for microamp measurements?
Usually yes — on most meters the µA and mA ranges share the same input jack, with the dial selecting the range, not a separate port. Check your specific meter's markings, since a few models do use a dedicated jack for very low currents.
Why does my reading drift slowly instead of settling?
At microamp levels, stray capacitance in the test leads and circuit can take a moment to charge or discharge through the tiny current being measured, causing a slow settling drift rather than an instant stable reading. Waiting a few seconds before recording the value usually resolves it.
Is a cheap multimeter accurate enough for microamp measurements?
It depends on what you need the number for. Cheaper meters often have higher burden voltage and more noise at the low end of their µA range, which matters for precise comparisons but is usually fine for simply confirming whether a circuit draws a lot or a little current. For precise bias-current or leakage work, a meter with a stated, tighter µA accuracy spec is worth the extra cost.
Does this range have the same fuse-protection concern as milliamps?
Yes, the same principle applies: current mode is a near-zero-resistance path, so connecting it across a voltage source by mistake, rather than in series within the circuit, risks blowing the meter's internal fuse just as it would on the mA range. See our how-to-measure-milliamps guide for the full explanation of how the fuse protects the meter.
How do I know if my multimeter actually has a µA range?
Check the model's own published spec sheet rather than assuming — it is not universal even within one maker's lineup. Fluke's own datasheet for its 114/115/116/117 family lists a µA range only on the 116, for example; the 117 has none at all despite looking like a similar general-purpose meter. Look for 'µA' printed on the dial or in the manufacturer's current-range table before relying on a meter for this measurement.
