A 2-10 V humidity sensor at 6.4 V
The span is 8 V, and 6.4 V is 4.4 V above the 2 V live zero: 4.4 ÷ 8 = 55% of span, so the reading is 55 %RH.
Measured value 55 %RH Open in the calculator
0-10 V signal scaling calculator
Convert an analogue voltage signal to the value it represents, or a value to the voltage a sensor should output, for 0-10 V, 2-10 V, 1-5 V or any linear range.
Measured value
50%
Check the values to see a result.
- Position in the span
- 50%
How it’s calculated
- Value = low + (V − Vlow) × (high − low) ÷ (Vhigh − Vlow)=0 + (5 − 0) × (100 − 0) ÷ (10 − 0)=50 %
Value = low + (V − Vlow) × (high − low) ÷ (Vhigh − Vlow)
5 V on a 0-10 V signal ranged 0 to 100% reads 50%.
Tip: A 2-10 V signal reserves voltages below 2 V for faults rather than valid readings. An open wire does not necessarily read 0 V: fault detection depends on the receiver input bias or diagnostics, and an unconnected input may float.
How to convert 0-10 V to engineering units
A 0-10 V sensor outputs a voltage in proportion to its reading: 0 V at the bottom of its range, 10 V at the top. To convert, find how far the voltage is along the signal span and apply that share to the measuring range. 5 V on a 0 to 100% humidity sensor is 50%. The same method works for 2-10 V, 0-5 V and 1-5 V signals.
Voltage to value
value = low + (V − Vlow) × (high − low) ÷ (Vhigh − Vlow)
Vlow and Vhigh are the signal limits (0 and 10 V, or 2 and 10 V), and low and high are the readings at those limits.
Value to voltage
V = Vlow + (value − low) × (Vhigh − Vlow) ÷ (high − low)
Use this to check a sensor: at a known condition, work out the voltage it should give and measure it.
0-10 V to percentage
% = V × 10
For a plain 0-10 V signal each volt is 10% of span. For 2-10 V, the span is 8 V: % = (V − 2) ÷ 8 × 100.
With a 2-10 V or 1-5 V live-zero signal, 0 V is outside the valid measuring range. A low voltage can indicate a broken wire only when the receiver input has defined bias or diagnostics: an open input may float instead of reading 0 V. A plain 0-10 V signal cannot identify a broken wire from a zero reading alone.
0-10 V scaling examples
A 0-10 V temperature sensor ranged −20 to 80 °C
Each volt is 10 °C of the 100 °C range. At 3.7 V the reading is −20 + 3.7 × 10 = 17 °C.
Measured value 17 °C Open in the calculator
Checking a 1-5 V pressure transmitter
At 4 bar on a 0 to 16 bar range the transmitter is at a quarter of span, so it should output 1 + 0.25 × 4 = 2 V. A 1-5 V signal is often a 4-20 mA loop measured across a 250 Ω resistor.
Signal voltage 2 V Open in the calculator
0-10 V and 2-10 V to percentage table
Each whole volt as a share of span for the two most common building-automation signals.
| Signal (V) | 0-10 V | 2-10 V |
|---|---|---|
| 0 | 0% | Below range |
| 1 | 10% | Below range |
| 2 | 20% | 0% |
| 3 | 30% | 12.5% |
| 4 | 40% | 25% |
| 5 | 50% | 37.5% |
| 6 | 60% | 50% |
| 7 | 70% | 62.5% |
| 8 | 80% | 75% |
| 9 | 90% | 87.5% |
| 10 | 100% | 100% |
Questions about 0-10 V scaling
How do I convert 0-10 V to a percentage?
Multiply the voltage by 10: 7.5 V is 75%. For 2-10 V, subtract 2, divide by 8 and multiply by 100: 7.5 V is 68.75%.
Should I use 0-10 V or 4-20 mA?
Voltage signals are simple and common in HVAC, but cable resistance and electrical noise shift them, so keep runs short. A 4-20 mA loop is unaffected by cable resistance within its supply budget and suits long runs; see the 4-20 mA scaling calculator.
Can I read a 4-20 mA signal as a voltage?
Yes, across a precision resistor: 250 Ω turns 4-20 mA into 1-5 V. Check that the loop supply has enough voltage left to drive the resistor.
Limits of this result
- The calculation does not include source impedance, input loading, ground offset, isolation or cable noise.
- A nonlinear sensor requires its own transfer function or calibration table.
Log the signal continuously
ZIO and ZVO read 4-20 mA and 0-10 V instruments and send the readings to the Gateway over the wireless mesh.
