# Digital Multimeter Uncertainties

Click the link below to go to the specifications for your digital multimeter.

### Tutorial: Understanding the DMM's Uncertainty Specifications

Uncertainties for digital multimeters (DMMs) are always listed as a percentage of the reading plus some integer-multiple of the least significant digit (dgt) on the scale.

e.g.   ±(2.5% + 3 dgt)

So, for example, if we measure a voltage of 32.00V on a scale that has the uncertainty listed above (where 0.01V is the least significant digit on that scale), then the absolute uncertainty of our reading will be:

(32.00 × 0.025) = 0.8
+   (3 × 0.01) = 0.03
= 0.83 ⇒ ±0.8V

Notice how 3×(the least significant digit) made a negligible contribution to the total uncertainty in this example. However, if we measure a voltage of 0.09V on the same scale, then the absolute uncertainty will be:

(0.09 × 0.025) = 0.00225
+   (3 × 0.01) = 0.03
= 0.03225 ⇒ 0.03V

This demonstrates why it's important to use the most sensitive scale on the DMM that will still measure your reading. In this case, 3×(the least significant digit) was the major contribution, and it gave us an uncertainty that is very large compared to our value. Using a more sensitive scale should give us a better (i.e. smaller) uncertainty.

### B & K 2712

Setting Range Resolution Accuracy
DC Voltage 400 mV
4 V
40 V
400 V
1000 V
0.01 mV ±(0.15% + 10 dgt) on 400 mV range
±(0.1% + 5 dgt) on 4 V range
±(0.1% + 5 dgt) on 40 V range
±(0.1% + 5 dgt) on 400 V range
±(0.1% + 5 dgt) on 1000 V range
AC Voltage
(True RMS 45-1000Hz)
400 mV
4 V
40 V
400 V
750 V
0.01 mV ±(1.5% + 20 dgt) 45-60 Hz on 400 mV to 400 V ranges
±(1.5% + 20 dgt) 60-500 Hz on 4V range
±(1.5% + 20 dgt) 60Hz - 1kHz on 40 V to 400V ranges

±(2.0% + 20 dgt) 45-500 Hz on 750 V range
AC+DC Voltage
(True RMS 45-1000Hz)
400 mV
4V
40V
400V
750V
0.01 mV ±(2.0% + 20 dgt) 45-60 Hz on 400 mV to 400 V ranges
±(2.0% + 20 dgt) 60-500 Hz on 4V range
±(2.0% + 20 dgt) 60Hz - 1kHz on 40 V to 400 V ranges

±(2.0% + 20 dgt) 45-500 Hz on 750 V range
DC Current 40 mA
400 mA
10 A
1 μA ±(0.5% + 10 dgt) on 40 mA to 400 mA ranges

±(1.5% + 10 dgt) on 10 A range
AC Current
(True RMS 50-1000Hz)
40 mA
400 mA
10 A
1 μA ±(2.0% + 10 dgt) on 40 mA to 400 mA ranges

±(2.5% + 10 dgt) on 10 A range
Resistance 400 Ω
4 kΩ
40 kΩ
400 kΩ
4 MΩ
40 MΩ
0.01 Ω ±(0.3% + 15 dgt) on 400 Ω range
±(0.3% + 5 dgt) on 4 kΩ to 400 kΩ ranges

±(0.5% + 10 dgt) on 4 MΩ range
±(1.5% + 20 dgt) on 40 MΩ range
Capacitance 4 nF
40 nF
400 nF
4 μF
40 μF
1 pF ±(3.0% + 20 dgt) on 4 nF range
±(3.0% + 5 dgt) on 40 nF to 400 nF ranges

±(3.0% + 5 dgt) on 4 μF to 20 μF ranges
±(5.0% + 5 dgt) on 20 μF to 40 μF ranges
Frequency 100 Hz
1 kHz
10 kHz
100 kHz
500 kHz
0.01 Hz ±(0.1% + 10 dgt)

### B & K 2709B

Setting Range Resolution Accuracy
DC Voltage 660 mV
6.6 V
66 V
660 V
1000 V
0.1 mV ±(0.5% + 2 dgt)
AC Voltage
(True RMS 50-500Hz)
660 mV
6.6 V
66 V
660 V
750 V
0.1 mV ±(1.5% + 8 dgt) 50-60 Hz for 660 mV range
±(1.5% + 8 dgt) on 6.6 V to 660 V ranges

±(2.0% + 8 dgt) on 750 V range
DC Current 660 μA
6600 A
66 mA
400 mA
10 A
0.1 μA ±(1.5% + 2 dgt) on 660 μA to 400 mA ranges

±(3.0% + 3 dgt) on 10 A ranges
AC Current
(True RMS 50-500Hz)
660 μA
6600 A
66 mA
400 mA
10 A
0.1 μA ±(2.0% + 10 dgt) on 660 μA to 400 mA ranges

±(3.5% + 10 dgt) on 10 A ranges
Resistance 660 Ω
6.6 kΩ
66 kΩ
660 kΩ
6.6 MΩ
66 MΩ
0.1 Ω ±(1.2% + 5 dgt) on 660 Ω to 660 kΩ ranges

±(2.0% + 5 dgt) on 6.6 MΩ range
±(3.5% + 5 dgt) on 66 MΩ range
Capacitance 6.6 nF
66 nF
660 nF
6.6 μF
660 μF
6.6 mF
66 mF
1 pF ±(3.0 % + 30 dgt) on 6.6 nF scale
±(3.0 % + 5 dgt) on 66 nF to 660 μF ranges

±(3.0 % + 20 dgt) on 6.6 mF and 66 mF ranges
Frequency 660 Hz
6.6 kHz
66 kHz
660 kHz
6.6 MHz
66 MHz
0.1 Hz ±(0.1 % + 3 dgt)

### B & K 388-HD

Setting Range Resolution Accuracy
DC Voltage 200 mV
2 V
20 V
200 V
1000 V
100 μV
1 mV
10 mV
100 mV
1 V
± (0.5 % + 1 dgt)
AC Voltage 200 mV
2 V
20 V
200 V
750 V
100 μV
1 mV
10 mV
100 mV
1 V
±(1.25 % + 4 dgt)  40  - 1 kHz on 200 mV to 200 V ranges

±(1.25 % + 4 dgt)  40 - 400 Hz on 750 V range
DC Current 200 μA
2 mA
20 mA
200 mA
2 A
20 A
0.1 μA
1 μA
10 μA
100 μA
1 mA
10 mA
±(1.0 % + 1 dgt) on 200 μA to 200 mA ranges

±(2.0 % + 3 dgt) on 2A and 20 A ranges
AC Current 200 μA
2 mA
20 mA
200 mA
2 A
20 A
0.1 μA
1 μA
10 μA
100 μA
1 mA
10 mA
±(1.5 % + 3 dgt) 40 - 1 kHz on 200 μA to 200 mA ranges

±(2.5 % + 3 dgt) 40 - 400 Hz on 2A and 20 A ranges
Resistance 200 Ω
2 kΩ
20 kΩ
200 kΩ
2 MΩ
20 MΩ
2000 MΩ
0.1 Ω
1 Ω
10 Ω
100 Ω
1 kΩ
10 kΩ
1 MΩ
±(0.75 % + 4 dgt) for 200 Ω range
±(0.75 % + 1 dgt) on 2 kΩ to 2 MΩ ranges

±(1.5 % + 5 dgt) on 20 MΩ range
±(5 % + 10 dgt) on 2000 MΩ range
Capacitance 2 nF
20 nF
200 nF
2 μF
20 μF
1 pF
10 pF
100 pF
1 nF
10 nF
±(2.0 % + 4 dgt)
Frequency 2 kHz
20 kHz
200 kHz
1 Hz
10 Hz
100 Hz
±(1.0 % + 3 dgt)

### Fluke 75

Setting Range Resolution Accuracy
DC Voltage 320 mV 0.1 mV ±(0.4 % + 1 dgt)
DC Voltage 3.200 V
32.00 V
320 V
1000 V
0.001 V
0.01 V
0.1 V
1 V
±(0.4 % + 1 dgt)
AC Voltage 3.200 V
32.00 V
320 V
750 V
0.001 V
0.01 V
0.1 V
1 V
±(2.0 % + 2 dgt)  45  - 500 Hz on 3.2 V range
±(2.0 % + 2 dgt)  45 - 1 kHz on 32 V to 750 V ranges
DC Current 32.00 mA
320 mA
10.0 A
0.01 mA
0.1 mA
0.01 A
±(1.5 % + 1 dgt)
AC Current 32.00 mA
320 mA
10.0 A
0.01 mA
0.1 mA
0.01 A
±(2.4 % + 2 dgt) 45 - 1 kHz
Resistance 320.0   Ω
3200 Ω
32.00 Ω
320.0  kΩ
3.200 MΩ
32.00 MΩ
0.1 Ω
1 Ω
10Ω
100Ω
1 kΩ
10 kΩ
±(0.5 % + 2 dgt) on 320 Ω range
±(0.5 % + 1 dgt) on 3200 Ω to 3.200 MΩ ranges

±(2 % + 1 dgt) on 32.00 MΩ range

### Fluke 115

Setting Range Resolution Accuracy
DC Voltage 600.0 mV 0.1 mV ± (0.5 % + 2 dgt)
DC Voltage 6.00 V
60.00 V
600.0 V
0.001 V
0.01 V
0.1 V
±(0.5 % + 2 dgt)
AC Voltage
(True RMS)
600.0 mV 0.1 mV ±(1.0 % + 3 dgt) 45 - 500 Hz ±(2.0 % + 3 dgt) 500 - 1 kHz
AC Voltage
(True RMS)
6.000 V
60.00 V
600.0 V
0.001 V
0.01 V
0.1 V
±(1.0 % + 3 dgt)  45  - 500 Hz ±(2.0 % + 3 dgt) 500 - 1 kHz
DC Current 6.000 A
10.00 A
20 A
0.001 A
0.01 A
±(1.0 % + 3 dgt)
AC Current
(True RMS)
6.000 A
10.00 A
20 A
0.001 A
0.01 A
±(1.5 % + 3 dgt)  45 - 500 Hz
Resistance 600.0 Ω
6.000 kΩ
60.00 kΩ
600.0 kΩ
6.000 MΩ
40.00 MΩ
0.1 Ω
0.001 kΩ
0.01 kΩ
0.1 kΩ
0.001 MΩ
0.01 MΩ
±(0.9 % + 2 dgt) on 600 Ω range
±(0.9 % + 1 dgt) on 6 kΩ to 6 MΩ ranges

±(5 % + 2 dgt) on 40 MΩ range
Capacitance 1000 nF
10.00 μF
100.0 μF
9999 μF
1 nF
0.01 μF
0.1 μF
1 μF
±(1.9 % + 2 dgt) for 1000 nF and 10 μF ranges

for 100 - 1000 μF: ±(1.9 % + 2 dgt),
for greater than 1000 μF: ±(5 % + 20 dgt)
Frequency 99.99 Hz
999.9 Hz
9.999 kHz
50.00 kHz
0.01 Hz
0.1 Hz
0.001 kHz
0.01 kHz
±(0.1 % + 2 dgt)

### Fluke 175

Setting Range Resolution Accuracy
DC Voltage 600.0 mV 0.1 mV ±(0.15 % + 2 dgt)
DC Voltage 6.00 V
60.00 V
600.0 V
1000 V
0.001 V
0.01 V
0.1 V
1 V
±(0.15 % + 2 dgt)
AC Voltage
(True RMS)
600.0 mV
6.000 V
60.00 V
600.0 V
1000 V
0.1 mV
0.001 V
0.01 V
0.1 V
1 V
±(1.0 % + 3 dgt)  45  - 500 Hz ±(2.0 % + 3 dgt) 500 - 1 kHz
DC Current 60.00 mA
400.0 mA
6.000 A
10.00 A
0.01 mA 0.1 mA 0.001 A 0.01 A ±(1.0 % + 3 dgt)
AC Current
(True RMS)
60.00 mA
400.0 mA
6.000 A
10.00 A
0.01 mA
0.1 mA
0.001 A
0.01 A
±(1.5 % + 3 dgt)  45 - 1 kHz
Resistance 600.0 Ω
6.000 kΩ
60.00 kΩ
600.0 kΩ
6.000 MΩ
50.00 MΩ
0.1 Ω
0.001 kΩ
0.01 kΩ
0.1 kΩ
0.001 MΩ
0.01 MΩ
±(0.9 % + 2 dgt) for 600 Ω range
±(0.9 % + 1 dgt) for 6 kΩ to 6 MΩ ranges

±(1.5 % + 3 dgt) for 50 MΩ range
Capacitance 1000 nF
10.00 μF
100.0 μF
9999 μF
1 nF
0.01 μF
0.1 μF
1 μF
±(1.2 % + 2 dgt) for 1000 nF to 100 μF ranges

±10 % for 9999 μF range
Frequency 99.99 Hz
999.9 Hz
9.999 kHz
99.99 kHz
0.01 Hz
0.1 Hz
0.001 kHz
0.01 kHz
±(0.1 % + 1 dgt)