---
title: "Wrench Time Benchmarks: Typical, Good, and World-Class Rates"
slug: wrench-time-benchmarks-typical-good-and-world-class-rates
url: /topics/guides/wrench-time-benchmarks-typical-good-and-world-class-rates/index.md
publishedAt: "2026-06-15T19:07:28"
updatedAt: "2026-06-15T19:07:28"
excerpt: "Ask ten maintenance managers what “good” wrench time looks like and you’ll get ten answers, most of them wrong in the optimistic direction. The figure that gets repeated most is 25 to 35 percent for a typical site and about 55 percent for world-class. Dig into the primary sources and it’s a bit messier: Palmer’s […]"
authors:
  - Reliable Media
---

# Wrench Time Benchmarks: Typical, Good, and World-Class Rates

By [Reliable Media](/authors/reliable-media/index.md)

Ask ten maintenance managers what “good” wrench time looks like and you’ll get ten answers, most of them wrong in the optimistic direction.

The figure that gets repeated most is 25 to 35 percent for a typical site and about 55 percent for world-class. Dig into the primary sources and it’s a bit messier: Palmer’s open writing points to roughly 35 percent typical, and Smith and Mobley put most companies at 18 to 30 percent. The 55 percent world-class mark is Palmer’s best-practice benchmark.

That gap is a real pool of recoverable labor, and tapping it doesn’t cost a single new hire.

## What wrench time measures, and where the numbers come from

Wrench time is the share of a technician’s available shift spent making productive progress on a job. The narrowest reading counts only hands-on tool time. Palmer’s reading is broader: any activity that moves the job forward, which can take in troubleshooting, lockout/tagout, and job-site paperwork. Both readings strip out the big time sinks, travel, waiting for parts, hunting for tools, and breaks. The line between the two readings is exactly where definitions drift, which we cover below.

Wrench time is a recognized best-practice metric. SMRP lists it as Metric 5.6.1 in its Best Practices metrics set, which gives practitioners a common reference point. That recognition doesn’t settle the definition, though. The detailed SMRP definition, and any best-in-class target, sit in the members-only document, and field teams still draw the productive line in different places.

The numeric targets are a different story. No published ISO or EN standard sets a “world-class” wrench time figure. The typical and best-practice numbers come from practitioner literature, chiefly Doc Palmer and the team of Ricky Smith and R. Keith Mobley, both writing from decades of plant-floor work sampling. That distinction matters for how confident you should be, so we built it into the table.

## The Reliable Confidence Score

## The Big Takeaway

Here’s where the real money is: the math on closing the gap.

Doc Palmer’s point is that the jump from typical to world-class looks small and pays huge. Moving a crew from 35 to 55 percent wrench time is a 57 percent gain in capacity (55 ÷ 35 = 1.57). In Palmer’s model, those recovered hours flow to proactive work, since the crew was already sized to cover the reactive load.

> Going from 35 to 55 percent wrench time turns a 30-person crew into the equivalent of 47 people, with nobody new on the payroll. That is the whole business case for planning and scheduling in one ratio.

That 57 percent is theoretical capacity, not an automatic result. Turning it into real output still needs the backlog, parts, supervision, and equipment access to fill the recovered hours, and some of that capacity gets absorbed by corrective or emergent work. The leverage is real because the cost is fixed: you’re paying for the full shift either way, and wrench time tells you how much of it reaches the equipment.

## Why the numbers vary

The same plant can post very different wrench time numbers depending on how you measure it.

Study design drives most of the spread. A one-day snapshot during a turnaround week says nothing about normal operations. A rolling work sampling study across several weeks gives a stable number. The two can differ by a wide margin.

Observation changes behavior. Crews who feel watched look busier, and technicians who suspect a headcount cut is coming will look very busy during the study window. That alone can inflate a result.

Definition drift is the quiet one. If one plant counts “walking to the storeroom” as productive and another counts it as travel, their numbers aren’t comparable even when both call the metric “wrench time.” This is why the SMRP 5.6.1 definition matters more than the benchmark.

Plant type sets the ceiling. A heavy process environment with vessel entry, lockout/tagout, and remote equipment access has less room to run than a general manufacturing line, because access and permitting eat into every job. The same planning program will land at different numbers in those two settings.

## How to use the benchmark safely

Compare yourself to yourself. Run a consistent work sampling study, fix your top three time-wasters, then re-measure in 90 days. Your own trend line is worth more than another plant’s number measured under different rules.

Pair it with context. Wrench time read alone is misleading. Read it next to schedule compliance, backlog, and planned work percentage, and the picture of whether work management is leaking hours gets clear.

Set a realistic target. A team starting low can often book a meaningful gain in the first improvement cycle, then build from there. A sustained move to best-practice levels is a long-term program built on consistent planning and scheduling.

## Where teams go wrong

They chase 65 percent. The defensible anchor is 55 percent. Before trusting a number above 60 percent, check how the plant defines and measures wrench time, because small differences there can swing the result.

They weaponize the metric. Palmer’s own caution is blunt: you don’t have to measure wrench time, and if you turn it into a surveillance tool, the data becomes useless and the crews stop trusting you. Use it to find process leaks, not to justify cuts.

They confuse it with other metrics. Wrench time, utilization, and Mean Time to Repair measure different things, and each gets defined differently from shop to shop. Wrench time tracks the productive share of a shift; MTTR tracks how long a repair takes. Treating them as interchangeable, or assuming everyone draws the lines the same way, produces nonsense benchmarks.

## Methodology

We pulled the figures from primary practitioner sources and the standards framework, then rated each one on the Reliable Confidence Score.

Palmer’s open writing supports a typical figure near 35 percent and a 55 percent best practice, so those anchors carry the most weight. The wider 25 to 35 percent band, and the Smith and Mobley ranges (18 to 30 percent for most companies, 55 to 65 percent at the top), come from the paid literature, including Smith and Mobley’s Rules of Thumb for Maintenance and Reliability Engineers (Butterworth-Heinemann, 2007), so we rated those Medium. The 57 percent figure is Palmer’s arithmetic (55 ÷ 35), which we treat as theoretical capacity rather than a measured field outcome.

One honest caveat sits behind two of the Medium ratings. No published ISO or EN standard sets a numeric wrench time target. The world-class numbers are practitioner consensus, and SMRP’s own best-in-class figure for Metric 5.6.1 lives behind its members-only Best Practices document, so we could not verify the exact value in open material.

## Bottom Line

The figure everyone repeats is 25 to 35 percent typical. The primary sources are lower and narrower: about 35 percent from Palmer, 18 to 30 percent from Smith and Mobley. Best practice, the level most people call world-class, is about 55 percent. The prize for closing that gap, in Palmer’s model, is a 57 percent gain in capacity, headroom that turns into proactive work when the backlog and parts are there to fill it.

Measure it carefully with a real work sampling study, or follow Palmer’s advice and don’t measure it at all. A bad wrench time number does more damage than no number.

## Sources

* Doc Palmer, *Maintenance Planning and Scheduling Handbook*, McGraw-Hill. [https://books.google.com/books/about/Maintenance_Planning_and_Scheduling_Hand.html?id=CT5zaQC0uKAC](https://books.google.com/books/about/Maintenance_Planning_and_Scheduling_Hand.html?id=CT5zaQC0uKAC)
* Doc Palmer, “Plan-it fitness: the great value of maintenance planning,” *Plant Services* (Palmer’s Planning Corner). [https://www.plantservices.com/planned-maintenance/planning-and-scheduling/article/11303144/plan-it-fitness-the-great-value-of-maintenance-planning](https://www.plantservices.com/planned-maintenance/planning-and-scheduling/article/11303144/plan-it-fitness-the-great-value-of-maintenance-planning)
* Doc Palmer, “Understanding the math of maintenance planning and scheduling,” *Plant Services*. [https://www.plantservices.com/planned-maintenance/planning-and-scheduling/article/11295301/understanding-the-math-of-maintenance-planning-and-scheduling](https://www.plantservices.com/planned-maintenance/planning-and-scheduling/article/11295301/understanding-the-math-of-maintenance-planning-and-scheduling)
* Ricky Smith and R. Keith Mobley, *Rules of Thumb for Maintenance and Reliability Engineers*, Butterworth-Heinemann/Elsevier, 2007 (ISBN 9780750678629). [https://shop.elsevier.com/books/rules-of-thumb-for-maintenance-and-reliability-engineers/smith/978-0-7506-7862-9](https://shop.elsevier.com/books/rules-of-thumb-for-maintenance-and-reliability-engineers/smith/978-0-7506-7862-9)
* SMRP, *Best Practices, Metrics and Guidelines* (the metrics set that includes Wrench Time). [https://smrp.org/Learning-Resources/SMRP-Library/Best-Practices-Metrics-Guidelines](https://smrp.org/Learning-Resources/SMRP-Library/Best-Practices-Metrics-Guidelines)
* SMRP Best Practices Metrics Workshop (lists Wrench Time as Metric 5.6.1 under Pillar 5, Work Management), hosted by PEMAC. [https://pemac.org/sites/default/files/2018_SMRP_BPMW_Full_Day.pdf](https://pemac.org/sites/default/files/2018_SMRP_BPMW_Full_Day.pdf)

## Frequently Asked Questions

### What is a typical wrench time percentage?

The figure most often repeated is 25 to 35 percent of a technician's shift. The primary sources differ a little: Doc Palmer's published work puts a typical good plant near 35 percent, while Ricky Smith and R. Keith Mobley report most companies at 18 to 30 percent in Rules of Thumb for Maintenance and Reliability Engineers.

### What is world-class wrench time?

About 55 percent. Doc Palmer calls 55 percent best practice and achievable, and warns that 80 percent is unrealistic. It is widely used as the world-class label, but it is Palmer's benchmark rather than a codified cross-industry standard. Smith and Mobley cite a 55 to 65 percent range at the top.

### What does wrench time measure, and what does it exclude?

Wrench time is the share of a technician's available shift spent making productive progress on a job. The narrowest reading counts only hands-on tool time, while Doc Palmer's broader reading includes any work that moves the job forward, such as troubleshooting and lockout/tagout. Both readings exclude travel, waiting for parts, hunting for tools, and breaks. SMRP lists it as Metric 5.6.1.

### How much can improving wrench time increase output?

Moving a crew from 35 to 55 percent wrench time is a 57 percent gain in capacity, since 55 divided by 35 equals 1.57. The calculation is Doc Palmer's. That is theoretical capacity rather than guaranteed output: realizing it depends on having the backlog, parts, supervision, and equipment access to fill the recovered hours.

### Is wrench time an official SMRP metric?

Yes. SMRP lists Wrench Time as Metric 5.6.1 under Pillar 5, Work Management, in its Best Practices metrics set. The detailed SMRP definition and any best-in-class target sit in the members-only Best Practices document, so specific SMRP target numbers should be treated as commonly cited rather than openly verified.

### Why do wrench time numbers vary so much between studies?

Mostly study design and definitions. A one-day snapshot during a turnaround differs from a multi-week work sampling study, observation can change how busy crews look, and plants draw the line between productive and non-productive time in different places. Plant type matters too, since heavy process sites with vessel entry and permitting have less room to run than general manufacturing.

### Should I measure wrench time?

Doc Palmer's caution is that you do not have to measure it, and turning it into a surveillance tool makes the data useless and erodes trust. If you do measure it, use a proper work sampling study and read it alongside schedule compliance and backlog rather than as a standalone productivity score.