# Maintenance Crew Size Calculator

> Source: https://netray.co/tools/maintenance-crew-size-wrench-time-calculator
> Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems.
> Section: Free Tools

## Short answer

Turn weekly maintenance workload into a required headcount, using real productive hours per technician after absence and wrench time.

## Category

maintenance

## Industry

Manufacturing

## Audience

- Maintenance manager
- Plant manager
- Maintenance planner

## Tool

**Kind:** calculator

**Currency:** $

**Inputs:**

#### Preventive maintenance hours per week

**Key:** pm_hours

**Type:** number

**Default:** 180

**Min:** 0

**Step:** 5

**Unit:** hours

#### Corrective and breakdown hours per week

**Key:** cm_hours

**Type:** number

**Default:** 220

**Min:** 0

**Step:** 5

**Unit:** hours

#### Project and improvement hours per week

**Key:** proj_hours

**Type:** number

**Default:** 40

**Min:** 0

**Step:** 5

**Unit:** hours

#### Paid hours per technician per week

**Key:** hrs_tech

**Type:** number

**Default:** 40

**Min:** 1

**Step:** 1

**Unit:** hours

#### Leave, training and meetings

**Key:** absence

**Type:** slider

**Default:** 12

**Min:** 0

**Max:** 40

**Step:** 1

**Unit:** %

**Help:** Share of paid hours not available for work orders.

#### Wrench time

**Key:** wrench

**Type:** slider

**Default:** 55

**Min:** 20

**Max:** 85

**Step:** 1

**Unit:** %

**Help:** Share of available hours spent actually doing the work, after travel, waiting and parts chasing.

#### Current technicians

**Key:** current

**Type:** number

**Default:** 8

**Min:** 0

**Step:** 1

#### Fully loaded cost per technician per year

**Key:** cost_tech

**Type:** number

**Default:** 78000

**Min:** 0

**Step:** 1000

**Unit:** $

**Outputs:**

#### Total workload

**Key:** work

**Expr:** pm_hours + cm_hours + proj_hours

**Format:** hours

#### Productive hours per technician

**Key:** prod

**Expr:** hrs_tech * (1 - absence / 100) * wrench / 100

**Format:** decimal

#### Technicians required

**Key:** required

**Expr:** work / prod

**Format:** decimal

**Primary:** true

#### Gap vs current crew

**Key:** gap

**Expr:** required - current

**Format:** decimal

#### Crew loading

**Key:** util

**Expr:** work / (current * prod) * 100

**Format:** percent

**Description:** Above 100 percent means the backlog is growing.

#### Backlog growth per week

**Key:** backlog_growth

**Expr:** max(work - current * prod, 0)

**Format:** hours

**Primary:** true

#### Annual cost of closing the gap

**Key:** gap_cost

**Expr:** max(gap, 0) * cost_tech

**Format:** currency

**Chart:**

#### Technicians required vs wrench time

**Type:** line

**X:** wrench

**From:** 30

**To:** 80

**Steps:** 25

**Series:**

- required

**Disclaimer:** Assumes the workload hours are productive (wrench) hours. If your work order estimates already include travel and delays, use a higher wrench time.

## Content

**Intro:** Maintenance headcount is usually argued from gut feel or a ratio. This calculator builds it from workload: how many hours of PM, breakdown and project work you carry, and how many of a technician's paid hours actually reach a work order.

**Sections:**

#### How to use it

**Body:** Enter weekly hours for PM, corrective and project work, taken from your CMMS or ERP work order history. Enter paid hours per technician, the share lost to leave, training and meetings, and your measured wrench time. The tool converts workload into required technicians, compares it with your current crew, and shows weekly backlog growth when the crew is overloaded. The chart sweeps wrench time to show how much headcount a few points of productivity are worth.

**Bullets:**

- Use actual hours booked on work orders, not planned estimates alone.
- Measure wrench time with a short observation study if you only have a guess.
- Include contractors by adding their hours to the crew in your own scenario.

#### The formula

**Body:** Productive hours per technician = paid hours x (1 - absence share) x wrench time share. Technicians required = total weekly workload divided by productive hours. Crew loading = workload divided by what the current crew can deliver. A typical industrial wrench time of 25 to 55 percent is common before improvements in planning, kitting and scheduling, so the same workload can need very different headcount.

#### Reading the result

**Body:** If loading is persistently above 100 percent, the backlog grows by the weekly overload hours, and the deferred work often returns as breakdowns. If loading is far below 100 percent, check whether the workload is understated because work is not being recorded. Compare the cost of closing the gap with the cost of raising wrench time, since improved planning often adds capacity cheaper than hiring.

#### Common mistakes

**Body:** Counting every paid hour as productive, ignoring shift coverage and skill mix, and using last year's reactive hours as next year's plan are the usual traps. Headcount must also cover trades: a surplus of mechanics does not fix a shortage of electricians. Use this as a first-pass capacity check, then validate by craft and shift in your ERP maintenance module.

**Cta:** If your work order hours live in SAP PM, Infor, Epicor or another ERP, Netray can help summarize them by craft and week so crew sizing uses real data. The calculator itself needs no contact.

**Faq:**

#### What is a realistic wrench time?

**Answer:** Studies of industrial maintenance often find 25 to 45 percent in reactive organizations and 50 to 65 percent in well planned ones. Measure your own with work sampling, because assumptions here move headcount more than any other input.

#### Should project hours be included?

**Answer:** Yes if the same crew does them. Capital projects and improvements compete for the same technicians, and leaving them out hides why PM compliance drops.

#### How do I handle several crafts?

**Answer:** Run the calculator once per craft, such as mechanical, electrical and instrumentation, using that craft's hours and headcount. Combined figures hide shortages in a single trade.

#### Does this include overtime?

**Answer:** No. Treat overtime as a symptom of a gap. If the gap is small and seasonal, overtime may be cheaper than a hire, but sustained overload argues for added capacity.

## Search terms

maintenance crew size calculator, how many maintenance technicians do i need, maintenance staffing calculator, maintenance headcount planning, maintenance workforce planning, wrench time staffing, maintenance labor requirement formula, maintenance staffing ratio

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