34401A
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The Keysight 34401A is a 6.5-digit bench digital multimeter. Keysight discontinued it on December 1, 2016, and recommends the 34461A Truevolt series as its replacement. That means a 34401A you find today is an older instrument, often used. This guide explains what the 34401A does, what Keysight’s pages state about it, how to use a bench meter safely, and what to check before you buy one.
Quick answer
- The 34401A is a bench multimeter with 6½-digit resolution, a 1,000-readings-per-second maximum rate and 512 readings of memory, according to Keysight’s migration page.
- Its DC current range is 3 A, according to the same page. The 34461A extends that range to 10 A.
- Keysight discontinued the 34401A on December 1, 2016, with November 30, 2016 as the last order day, and calls the 34461A a virtual drop-in replacement.
- The pages we opened do not state a CAT rating for the 34401A. Do not use it on mains or panel circuits on the basis of this guide.
What a bench multimeter is for
A bench multimeter sits on a workbench and stays connected to one job at a time. It is built for precise readings of DC and AC voltage, current and resistance, and it is often used to check power supplies, sensors and circuit boards. Compared with a handheld meter, a bench unit has more digits, more memory and usually an interface for logging readings to a computer. The 34401A is in that class.
The trade-off is that a bench meter is not a field tool. Its power cord, its leads and its rear-panel connections assume a stable workspace. If your work happens at a breaker panel, in a vehicle or on a roof, a handheld meter with a stated CAT rating is the better fit.
What the Keysight pages state
The table uses only the Keysight pages and the Fluke safety guide we opened on 2026-10-27. Where a page is silent, the cell says so.
| Item | What Keysight’s pages state |
|---|---|
| Resolution | 6½ digits for both the 34401A and the 34461A. |
| DC voltage accuracy | 40 ppm for the 34401A, compared with 35 ppm for the 34461A. |
| Maximum reading rate | 1,000 readings per second. |
| Reading memory | 512 readings. |
| DC current range | 3 A on the 34401A. The 34461A extends this to 10 A. |
| Display | One-line vacuum fluorescent display. The 34461A has a two-line color LCD. |
| Interfaces | GPIB and RS-232 on the 34401A. The 34461A adds USB and LAN. |
| Discontinued | December 1, 2016. Last order day November 30, 2016. |
| Support period | Keysight says it will support the product for a standard period of five years. |
| Standard shipped items | The 34401A, a power cord, a test lead kit, an IntuiLink CD software package and an RS-232 cable. |
| Options listed | A rack-mount kit (option 908) and a USB/GPIB interface for PC connection (option PCUSB), plus user’s guide language options. |
| Maximum voltage and current input | Not stated on the pages we opened, except the 3 A DC current range above. |
| CAT rating | Not stated on the pages we opened. |
| Fuse | Not stated on the pages we opened. |
How to use a 34401A safely
The Fluke safety guide we opened says to choose a meter rated for the highest category you might encounter, to match the voltage rating to the job, to check the rating printed on the instrument, and to stop using any meter or probe that is damaged. The guide is written for general use and does not cover bench instruments specifically. The 34401A’s rating is not stated on the pages we opened, so the rules below are conservative.
- Find the rating before the job. Read the rear and front panel labels on your unit. If no category is stated, do not connect it to mains or any circuit where a fault could deliver high energy.
- Use the bench for low-energy circuits. Power supplies, sensors, board-level electronics and battery packs are typical jobs. Confirm the voltage and current of the circuit before you connect the leads.
- Select the function first. Set voltage, current or resistance on the front panel before the probes touch the circuit. Never switch to a current or resistance function across a live source.
- Check the leads and the jacks. Inspect the test leads for cracks and exposed metal. Keep the leads in the correct input jack for the function.
- Use the 3 A range with care. The 34401A’s DC current range is 3 A. Put the meter in series with the circuit and watch for heat in the leads.
- Leave panel work to a licensed electrician. A bench meter does not make a live panel safe to open.
What to check before you buy a 34401A
- Discontinued status. Keysight stopped production on December 1, 2016. A unit for sale now is an older instrument, so ask the seller for its history and its condition.
- Interface. The 34401A uses GPIB and RS-232. If you plan to connect it to a modern computer, check whether you have an interface that matches. Keysight lists a USB/GPIB interface as an option for PC connection.
- Shipped items. The standard kit is the meter, a power cord, a test lead kit, IntuiLink CD software and an RS-232 cable. Confirm the seller includes the power cord and leads.
- Replacement path. Keysight recommends the 34461A for new purchases and calls it a virtual drop-in replacement. If you need current support or more current range, the 34461A is the option the manufacturer names.
- Calibration. The accuracy figures on Keysight’s comparison are specific to the instrument and its calibration. An old unit may need recalibration before you rely on its readings.
Common mistakes with a bench meter
- Assuming a bench meter is rated for mains. No category appears in the Keysight text we read.
- Measuring current in parallel. A current range in parallel with a source can blow the fuse or the meter’s input.
- Buying the 34401A for a 10 A job. Keysight’s page gives the 34401A a 3 A DC current range. The 34461A extends it to 10 A.
- Ignoring the support window. Keysight says it supports the product for five years after discontinuation. Long-term parts and service depend on the seller and the market.
FAQ
Is the 34401A still made?
No. Keysight says it discontinued the 34401A on December 1, 2016, and that the last order day was November 30, 2016.
What replaces it?
Keysight names the 34461A Truevolt series. Its migration page calls the 34461A a virtual drop-in replacement for the 34401A.
How many digits does it show?
Keysight lists 6½ digits, meaning a display that shows about six and a half digits of resolution.
What is the DC current range?
The migration page gives 3 A for the 34401A. It gives 10 A for the 34461A.
Can I use it on a household outlet?
Not on the basis of the pages we opened. No CAT rating is stated for the 34401A. Household outlets and panels call for a meter with a stated rating that covers the work.
Does it have a USB port?
The 34401A’s listed interfaces are GPIB and RS-232. Keysight lists a USB/GPIB interface as a separate option for PC connection.
How we chose
This explainer covers one model. It does not rank the 34401A against other bench meters. The facts come from the two Keysight pages and the Fluke safety guide we opened on 2026-10-27. Where a page is silent, the text says so.
What we could not verify
- A maximum voltage input for the 34401A. The pages we opened do not state one.
- A CAT rating or a fuse rating for the 34401A. The pages we opened do not state either.
- The operating manual’s full specification tables. The pages we opened give only the figures listed above.
- Current availability of parts or service. Keysight’s pages describe the discontinuation but not the parts market.
Bottom line
The Keysight 34401A is a discontinued 6½-digit bench multimeter with a 3 A DC current range. Keysight names the 34461A as its replacement. Use the 34401A on low-energy bench work, check the condition and interface before buying, and keep mains and panel work with a meter that has a stated CAT rating.
Related guides
- Best digital multimeter for electrical checks, the roundup that compares the 34401A with other choices.
- Best multimeters for electricians, for meters used on fixed installations.
- Best true RMS multimeters, for AC readings on non-linear signals.
Sources
- Keysight Technologies, “Migrate from the 34401A to the new 34461A Truevolt Digital Multimeter.” https://keysight.com/sg/en/lib/resources/technical-specifications/migrate-from-the-34401a-to-the-new-34461a-truevolt-digital-multimeter-dmm-2330612.html (opened 2026-10-27)
- Keysight Technologies, “34401A Standard Shipped Components.” https://www.keysight.com/at/de/lib/resources/reference-guides/34401a-standard-shipped-components-104022.html (opened 2026-10-27)
- Fluke Corporation, “Guide to digital multimeter safety.” https://fluke.com/en-us/learn/blog/safety/multimeter-guide (opened 2026-10-27)
