How to Use Relative Mode on a Multimeter
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How to use multimeter relative mode: select REL so the meter stores the reading on its display as a reference, resets the display to zero, and shows each later reading as the difference from that reference. The Fluke, Klein and UNI-T pages we opened describe the function in the same basic way. The button steps, the lists of functions and the limits differ by model, so check your own meter’s manual before you rely on any one step below.
Electrical safety
Mains circuits can kill. This guide covers low-voltage bench work only, and it gives no steps for live mains, outlets, panels or service wiring. Before you use any meter, check that its CAT rating suits the circuit you are testing, and read that rating from the listing or the manufacturer’s manual. Panel and service work belongs to a licensed electrician.
The sources we opened support that warning. OSHA says its electrical standards protect employees from “electric shock, electrocution, fires, and explosions.” The Klein MM720 manual warns that ignoring its warnings can cause severe injury or death. The Fluke 287/289 manual defines its warnings as covering actions that can cause bodily harm or death.
The Klein and Fluke manuals each state a CAT rating for their own meter. The Klein MM720 lists CAT IV 600 V and CAT III 1000 V, and the Fluke 87V MAX lists CAT III 1000 V and CAT IV 600 V under IEC 61010-2-033. The Klein manual places CAT III at the distribution part of a building’s low-voltage mains installation and CAT IV at its source. The Fluke 287/289 manual links CAT III to fixed installations such as distribution panels. These ratings apply to those models only.
Panel work is outside this guide. OSHA’s rule limits work on energized electric circuit parts to qualified persons, and it requires live parts to be deenergized before an employee works on or near them, unless that adds hazards or is infeasible. The Fluke 287/289 manual says servicing not covered in the manual should be done by qualified personnel only. The sources we opened name qualified persons, not licensed electricians, so the licensed-electrician advice above is our own recommendation.
Quick answer
- Relative mode stores the present reading as a reference and shows later readings as the difference from it (Fluke 87V MAX manual; UNI-T FAQ).
- On Klein MM720 and MM600 meters, the manuals say to take a first reading, press REL with the test leads connected, then take a second reading.
- On Fluke 287/289 meters, relative mode is chosen from the Menu softkeys, and the same REL softkey turns it off.
- The Fluke 287/289 manual does not allow relative mode in AC,DC or DC,AC modes, and the Fluke 87V MAX locks the range you have when you turn it on.
What relative mode does
Relative mode works from a stored reference point. The Fluke 87V MAX manual says that selecting relative mode zeroes the display and stores the present reading as the reference for later measurements. From then on the display shows the difference between the live reading and that reference. The manual’s example uses a stored reference of 15.00 V and a present reading of 14.10 V, and the display shows -0.90 V. It explains the minus sign as meaning the present input is lower than the stored reference.
The Fluke 287/289 manual describes the same idea with two displays. The live measurement moves to the secondary display, and the primary display shows the difference between the present measurement and the reference value. The UNI-T FAQ says the meter stores the existing reading, resets the display to zero, and sets a relative reference point for the next reading. The Fluke Learn page gives the shortest definition, describing REL as storing the existing reading as a delta and resetting the display to zero. The Klein MM1000 manual says that once you store the current value, the display shows the difference between the stored and live readings.
Which functions it works with
Each manual lists its own functions. The table shows what each opened manual states, and nothing beyond that.
| Meter manual | What the manual says relative mode works with |
|---|---|
| Klein MM720 | Voltage, current, resistance, temperature, capacitance and LoZ |
| Klein MM600 | Voltage, current, resistance, temperature and capacitance |
| Fluke 287/289 | The functions in its Figure 9, which the text we could read does not reproduce, plus frequency, duty cycle, pulse width, crest factor and dB |
| Fluke 87V MAX | Residual readings for capacitance and conductance; no full function list in the text we could read |
| UNI-T FAQ | Resistance and capacitance examples; no full list |
The Fluke 287/289 manual also covers low resistance. Its rotary switch position Y is the low-resistance setting, and the manual says only the relative functions, REL and REL%, work in that position. That position has a single range, so the manual disables the range button there. The Fluke 87V MAX manual describes the conductance case the same way: a conductance reading with the test leads open is normal, and relative mode can subtract it.
Turn it on and turn it off
The steps differ by meter, so the table gives each manual’s own steps.
| Meter manual | Turn on | Turn off |
|---|---|---|
| Klein MM720 and MM600 | Perform the first measurement, then with the test leads connected press REL to set the frame of reference, then perform the second measurement. | Not stated in either manual. |
| Klein MM1000 | Press to store the current value. | Press again to return to live reading. |
| Fluke 287/289 | Press Menu, move the menu selector to REL, then press the REL softkey (or REL%). | Press the same REL softkey again. |
| Fluke 87V MAX | Select relative mode with its relative key. | Press again to exit this mode. |
On the Klein MM720, the reference is set after the first reading. The displayed value is the difference between the first and second measurements, so the second reading is shown against the first.
Before you start
- Find the relative control in your meter’s manual first. The steps above differ by model, and the Fluke 287/289 reaches relative mode through the Menu softkeys.
- Choose the function and the range before you turn the mode on. The Fluke 87V MAX keeps the range you have at that moment.
- Set the lead condition the manual names for that function, such as leads together for resistance.
- Look for the relative indicator on the display. The Fluke 87V MAX manual lists one, which shows that the mode is active.
Two common uses
Lead resistance on a Fluke 287/289
- Step 1: Touch the probe tips together and read the leads. The manual describes this as reading the resistance of the leads.
- Step 2: Hold the tips together, press Menu, move the menu selector to REL, and press the REL softkey. This removes the lead resistance from later measurements.
- Step 3: Take your readings. After step 2, the manual says the displayed readings show the resistance at the probe tips.
If you are comparing meters for resistance work, see our ohm meter picks for resistance checks.
Capacitance and conductance residuals
On the Fluke 287/289, the manual has you open the menu, select REL, and then, with the test leads open, press REL to subtract the residual capacitance of the meter and leads. The manual gives this step to improve accuracy on small capacitors. The Fluke 87V MAX manual gives the same use for readings below 1000 nF.
The lead condition follows the function. The Fluke 287/289 manual uses leads together for resistance and leads open for capacitance and conductance residuals. Use the condition your own manual names for each function.
What relative mode does not do
- It does not work in every mode. The Fluke 287/289 manual does not allow MIN MAX, relative or relative percent in AC,DC or DC,AC modes.
- It does not free the range. The Fluke 87V MAX manual says the meter stays on the range selected when you press the key. On the Fluke 287/289, ranging is set to manual and cannot be changed, except for dB measurements. If you want a meter that picks its own range, compare our auto-ranging digital multimeter picks.
- It can add error in AC readings. The Fluke 287/289 manual says that with the leads shorted in the AC functions, the meter may show a residual reading of up to 200 counts, and that using REL to offset that reading may cause a much larger constant error in later measurements.
- A menu choice can clear it. On the Fluke 287/289, choosing the first menu item turns off all other functions and modes, and the manual’s example shows that choosing VAC clears both frequency and relative selections.
Common mistakes
- Reading the difference as the input. On the Fluke 87V MAX, a live reading of 14.10 V against a 15.00 V reference shows -0.90 V, so the display does not show the input voltage.
- Enabling it in AC,DC or DC,AC mode. The Fluke 287/289 manual does not allow relative mode in those modes, so set the function first.
- Using the wrong lead condition. The Fluke 287/289 manual calls for leads together for resistance and leads open for capacitance and conductance residuals.
- Setting the range after turning relative mode on. The Fluke 87V MAX manual locks the meter into the range you had when you pressed the key, so choose the range first.
How we chose
We looked for sources that describe relative mode in a manufacturer’s own manual or support page, and that state the steps or limits in plain words. We opened three Fluke sources (a Fluke Learn page and the 287/289 and 87V MAX manuals), three Klein manuals (MM720, MM600 and MM1000), one UNI-T FAQ page, and two OSHA pages for the electrical safety section. All nine were opened with curl on 2026-10-22. We kept only the sentences we found in the fetched text and paraphrased the rest. We left out retailer listings and search summaries. We did not rank meters or name a best model. We read the steps side by side because a manual is the closest available source for a model’s own controls, which is why each step names the manual it comes from.
What we could not verify
- How to turn relative mode off on the Klein MM720 and MM600. The manuals we opened do not say.
- The full function list for the Fluke 287/289. Its Figure 9 did not come through in the text we could read.
- The symbol for the relative key on the Fluke 87V MAX did not come through in the text we could read, so this guide refers to it only as the relative key.
- Whether a stored reference survives a power-off. None of the sources we opened say.
- Relative mode on meters outside these manuals. The sources we opened do not cover them, so check the manual for your model.
- Any license rule for panel work. The sources name qualified persons, not licensed electricians.
- CAT ratings for models not named here. The sources we opened do not state one for them.
Frequently asked questions
What does REL mean on a multimeter?
REL is the short label for relative mode. The Fluke 87V MAX manual lists a display indicator that shows relative mode is active.
How do I turn relative mode off?
It depends on the meter. The Fluke 87V MAX manual says to press the key again to exit, the Fluke 287/289 says the same REL softkey disables it, and the Klein MM1000 says a second press returns the display to the live reading. The Klein MM720 and MM600 manuals do not say.
Can I use it to remove test lead resistance?
Yes on the Fluke 287/289, which describes that use with the probe tips held together. The manual also says the test leads can add error to resistance measurements. The UNI-T FAQ gives a similar example: short the probes, then enable relative mode.
Does relative mode work in AC,DC mode?
Not on the Fluke 287/289, whose manual does not allow it in AC,DC or DC,AC. The sources we opened do not give the same rule for the Klein or UNI-T meters, so check your own manual.
Why does the display show a minus sign?
In relative mode, a minus sign means the live reading is lower than the stored reference, as in the 15.00 V example above.
Does relative mode correct a drifting reading?
The sources we opened do not describe a drift correction. The Fluke 287/289 manual warns about offsetting an AC residual with REL, so that case needs care.
Bottom line
Use relative mode to subtract a known reference, such as lead resistance or residual capacitance. Check the function, the range and the lead condition before you press the key, and check your manual for how to turn the mode off.
Sources
- https://meters.uni-trend.com/faqs/relative-rel-mode/ (opened 2026-10-22)
- https://www.fluke.com/en-us/learn/blog/digital-multimeters/multimeter-dial-button-jacks-display (opened 2026-10-22)
- https://assets.fluke.com/manuals/287_289_umeng0100.pdf (opened 2026-10-22)
- https://media.fluke.com/d6882a66-83b2-4309-9ea7-b10800c2b791_original%20file.pdf (opened 2026-10-22)
- https://data.kleintools.com/sites/all/product_assets/documents/instructions/klein/MM720_Manual_Web.pdf (opened 2026-10-22)
- https://data.kleintools.com/sites/all/product_assets/documents/instructions/klein/MM600_1390111ART_WEB.pdf (opened 2026-10-22)
- https://data.kleintools.com/sites/all/product_assets/documents/instructions/klein/MM1000_Manual_English.pdf (opened 2026-10-22)
- https://www.osha.gov/electrical (opened 2026-10-22)
- https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.333 (opened 2026-10-22)
