Standard work: the three elements, the documents and a worked example
Short answer
Standard work is the agreed, written way for an operator to do a repetitive job, built on three elements: takt time, a fixed work sequence and standard in-process stock. It is also called standardized work, and it is the baseline that every later improvement is measured against.
Standard work answers three questions for one operator in one process. How often must a piece come out (takt time)? In what order are the tasks done inside that time (work sequence)? How many pieces must sit in the process for the sequence to repeat (standard in-process stock)? The answers go on a standard work chart posted at the station. When someone finds a better way, the chart is rewritten and the new version becomes the standard.
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A short story from the plant floor
· 0:53
What's standard work? Explained like I'm five
A 60-second explainer of standard work. It works like a cookie recipe card on the fridge that everyone bakes from, and the card changes only when a test batch wins.
0:00Gurpreet. Explain standard work like I'm five.
0:04Standard work is documented best practice, executed consistently.
0:08No. Simpler.
0:10Okay. Picture a cookie recipe card on the fridge.
0:12Why a card? I just make cookies.
0:14Because the card holds the best way we know.
0:17But my cookies come out different every time.
0:20Everyone bakes from the same card. Same cookies, same safe steps.
0:24What if I find a yummier way?
0:26Test it. Bake one batch with less sugar.
0:29Then I change the card! Right now!
0:31Not yet. Only if the test batch wins.
0:34Then we rewrite the card. Everyone switches to it.
0:37So the card changes?
0:38Yes. It is always the best way we know, for now.
0:42The card isn't a cage. It's where improving starts.
0:45Best way, written down, same for everyone. Then we improve it.
0:49Exactly. Now go test a better cookie.
What is standard work?
Standard work is the written way one person does one repeating job: which tasks, in which order, in how much time, with how many pieces in the process. The Lean Enterprise Institute's Lean Lexicon defines standardized work as precise procedures for each operator's work, based on three elements. It is timed on the floor and posted where the work is done.
Standard work and standardized work mean the same thing. The English edition of Taiichi Ohno's book Toyota Production System says standard work. The Lean Lexicon and most Toyota material in English say standardized work. Plants use both, and so does this page.
The Lexicon lists what a plant gets from it: the current method is documented for every shift, variation between operators falls, new people are easier to train, injuries and strain go down, and there is a baseline for improvement. The last one matters most. Without a written current method, nobody can show that a change made the job better, because there is nothing fixed to compare it with.
The three elements of standard work
All three have to be present. If demand is unknown, there is no takt time to design the job around. If the order of tasks changes from person to person, the time changes with it. If the stock in the process is not fixed, the operator either waits for a piece or piles pieces up.
The three elements of standard work
Takt time
What it is
How often one piece has to be finished to meet customer demand.
How you get it
Available production time divided by customer demand for the same period. Use the takt time calculator.
Work sequence
What it is
The exact order in which the operator does the tasks inside takt time.
How you get it
Watch the job, list the tasks, time each one several times, then agree one order with the people who do it.
Standard in-process stock
What it is
The smallest number of pieces, including pieces in machines, that lets the sequence repeat without waiting.
How you get it
Walk the sequence and count the pieces that must be in machines or between steps when the operator starts the next cycle.
Takt time sets the pace, the work sequence sets the order and the standard in-process stock keeps the loop moving. Take one away and the other two stop holding. Source: Lean Enterprise Institute, Lean Lexicon, Standardized Work.
Ohno names the first element differently. In Toyota Production System: Beyond Large-Scale Production (Productivity Press, 1988) he lists cycle time, work sequence and standard inventory, and defines cycle time as the time allotted to make one piece. That is what the Lexicon and most plants now call takt time. Today cycle time usually means the time the job really takes, measured on the floor. Read with those meanings, the two sources agree. The Lexicon also notes that takt is a German word for a precise interval of time, such as a musical meter, and that it was first used as a production tool in the German aircraft industry in the 1930s.
The documents standard work is written on
The Lean Lexicon names three basic forms, used together, plus a training sheet. You do not need software to start. Each one is a free printable on this site.
Standard work documents and what each one shows
Process capacity sheet
What it shows
What each machine can make in a shift, from its manual time, machine time and tool changes. It finds the bottleneck.
Illustrative numbers. A cell machines a bracket on a lathe, a mill and a drill, then the operator deburrs, gauges and packs it. The shift has 450 minutes of working time, which is 450 x 60 = 27,000 seconds. The customer needs 300 brackets a day. Takt time is 27,000 / 300 = 90 seconds. Check it the other way: 300 pieces x 90 seconds = 27,000 seconds.
Work sequence for the bracket cell, times in seconds (illustrative)
Task
Manual
Machine runs alone
Walk to next
1. Unload and load the lathe, start it
12
40
3
2. Unload and load the mill, start it
14
35
3
3. Unload and load the drill, start it
10
20
3
4. Deburr and gauge the part
18
0
2
5. Pack the part, pick up a new blank
8
0
4
Manual work is 12 + 14 + 10 + 18 + 8 = 62 seconds. Walking is 3 + 3 + 3 + 2 + 4 = 15 seconds.
The same sequence drawn as a standard work combination table
Example numbers
Manual work
Machine runs alone
Walking
Takt time, 90 s
1. Unload and load the lathe, start itManual 12 s, machine 40 s, walk 3 s
2. Unload and load the mill, start itManual 14 s, machine 35 s, walk 3 s
3. Unload and load the drill, start itManual 10 s, machine 20 s, walk 3 s
4. Deburr and gauge the partManual 18 s, walk 2 s
5. Pack the part, pick up a new blankManual 8 s, walk 4 s
Operator cycle77 s of the 90 s takt time
0 s30 s60 s90 s
Five tasks drawn on a time line from 0 to 100 seconds. The operator's manual work and walking run end to end and finish at 77 seconds, before the takt time line at 90 seconds. Each machine keeps running after the operator has walked away, and all three finish before the operator returns.
Read down the dark bars: the operator is never in two places at once, and the last walk ends at 77 seconds, 13 seconds before the red takt line. The dashed lines are the machines running on their own while the operator is somewhere else.
The operator's cycle is manual work plus walking: 62 + 15 = 77 seconds. That is 13 seconds under the 90 second takt time, so one operator can run the cell: 77 / 90 = 0.86 of a person, rounded up to 1. Machine time is not added to the operator's cycle, because the operator walks away while each machine runs. That is the point of the combination table. It shows a person and three machines working at once.
The same cell as a standard work chart
Example numbers
1
Lathe
12 s by hand, 40 s machine
3 s
2
Mill
14 s by hand, 35 s machine
3 s
3
Drill
10 s by hand, 20 s machine
4 s
Takt 90 s
Cycle 77 s
3 s
5
Pack
8 s by hand
2 s
Operator walks this loop
4
Deburr and gauge
18 s by hand
The cell seen from above. The operator walks a loop: lathe, mill, drill along the top, then deburr and gauge, then pack, and back to the lathe. A yellow dot in each of the 3 machines marks one piece of standard in-process stock.
This is the sheet posted at the cell: the numbered sequence, the walking path, takt time 90 s, cycle time 77 s and 3 pieces of standard in-process stock (the yellow dots), one in each machine.
Standard in-process stock is 3 pieces, one in each machine. When the operator comes back to the lathe, the piece inside is finished and waiting. Take one of the three away and the operator has to stand and wait for a machine. Add a fourth and it sits on a bench with nowhere to go.
One more check comes from the process capacity sheet. The slowest machine is the lathe: 12 seconds to load plus 40 seconds to run is 52 seconds a piece, which is under takt. Over the shift it can make 27,000 / 52 = 519 pieces, leaving tool changes out to keep the sum short. Demand is 300, so no machine holds the cell back. The 13 spare seconds are the next thing to look at. If demand rises and takt time drops below 77 seconds, the sequence no longer fits and the standard has to be redesigned.
How to write standard work in six steps
Writing standard work in six steps
1
Work out takt time
2
Watch and list the tasks
3
Time each task
4
Draw the combination table
5
Set the standard stock and draw the chart
6
Train, post and audit
Steps 1 to 3 are done standing at the job with the operator, not at a desk.
1
Work out takt time
Take the working time in a shift, less breaks and planned stops, and divide it by what the customer needs in that shift.
2
Watch and list the tasks
Stand at the process or film it. Write each task the operator does as a short line starting with a verb.
3
Time each task
Time every task over several cycles and separate manual work, walking and machine time. Record the lowest time that the operator can repeat safely.
4
Draw the combination table
Plot the tasks as bars against a takt time line. If the operator's cycle runs past the line, move work to another person or remove waste before you go on.
5
Set the standard stock and draw the chart
Count the pieces the sequence needs, sketch the layout with the walking path, and add the safety and quality checks.
6
Train, post and audit
Teach the method with a job instruction sheet, post the chart at the station, and check it on a regular audit.
Write it with the operators, not for them. They know which motions are awkward and which checks get skipped at the end of a shift. When someone finds a better method, test it, then rewrite the documents. The Lexicon describes standardized work as the object of continuous improvement through kaizen. The standard is expected to change.
Standard work, SOPs and work instructions
The three get mixed up because all of them are written and all of them say how to do a job. They answer different questions, and most plants need all three.
Standard work against an SOP and a work instruction
Standard work
Question it answers
Can one person finish this sequence inside takt time, cycle after cycle?
Built on
Takt time, a timed sequence and a fixed number of pieces in process.
Fits best
Repetitive operator work in a cell or on a line.
Changes when
Demand changes or a kaizen finds a better sequence.
SOP
Question it answers
What is the approved procedure, and who is responsible for it?
Built on
Purpose, scope, responsibilities, safety and numbered steps.
Fits best
Any controlled activity, including ones done once a month.
Changes when
The process, the rules or the risks change.
Work instruction
Question it answers
How exactly do I do this one task?
Built on
Step by step detail with photos, settings and tolerances.
Fits best
A single task inside a job, at the point of use.
Changes when
The task, the tool or the part changes.
Standard work is the only one of the three tied to takt time. The other two say how to do a task, not how fast the whole loop must turn.
For the format of an SOP, see what SOP means and how to write one. Leader standard work is a different thing again: the daily and weekly routine of a team leader or manager, not an operator's cycle. It has its own page at leader standard work.
Is standard work the right document for this job?
1
Does one person repeat the same cycle, in a cell or on a line?
No
If no
Use an SOP or a checklist. A changeover or a repair has no repeating cycle to pace against takt.
Yes
2
Do you know the takt time for the line?
No
If no
Work it out first: available time divided by what the customer needs. The combination table is drawn against it.
Yes
3
Can you time each task over several cycles?
No
If no
Stand at the process or film it first. An average or a guess hides the awkward cycles.
Yes
Every answer right
Write standard work with the operators: the combination table, the chart and the standard stock.
Three questions in order. If no one repeats the same cycle, use an SOP or a checklist. If takt time is not known, work it out first. If the tasks cannot be timed over several cycles, film or watch the job first. Then write standard work with the operators.
Standard work needs a repeating cycle, a takt time and real timings. Without those three, another document fits better.
Common mistakes
Writing it in an office. A standard nobody on the floor helped to write is followed only while someone is watching.
Using an average time. An average hides the awkward cycles. Time several cycles and find out why the slow ones were slow.
Adding machine time to the operator's cycle. The cell then looks overloaded when the operator is free for most of the machine run.
Leaving out the stock. Without a fixed number of pieces in process the sequence breaks the first time a machine is empty.
Treating the chart as finished. If the date on it is three years old, either the job has not improved or the paper no longer matches the job.
Applying it where there is no repeating cycle. A changeover or a repair is better served by an SOP or a checklist. How many operators a line needs covers the staffing sum for lines that do repeat.
Where software helps
Paper is enough for one cell. It gets hard when there are hundreds of stations and the documents have to stay current across shifts and sites. LeanSuite covers most of that cycle in one platform: working out the standard with Vision AI, keeping it current with SOPs and work instructions, and training and auditing it. The standard work sheet and the standard work combination table are free LeanSuite templates, not modules in the software. See standardized work software for what each part does and does not do.
Standardized work software
Keep standard work current in LeanSuite
LeanSuite covers most of the cycle in one platform: working out the standard with Vision AI, keeping it current with SOPs and work instructions, and training and auditing it.
Bring the problem you are working on to a 45-minute demo. Or look around with sample data first, or pilot LeanSuite on your own lines for 90 days, with the setup done by our team.
Standard work is the agreed, written way for an operator to do a repetitive job. It is built on three elements: takt time, a fixed work sequence and standard in-process stock. It is posted at the station and used as the baseline for training, auditing and improvement.
Takt time, work sequence and standard in-process stock. The Lean Lexicon uses those names. Taiichi Ohno's book lists cycle time, work sequence and standard inventory, where his cycle time is the time allotted to make one piece, which is what plants now call takt time.
Yes. They are two English names for the same method. Ohno's book in English uses standard work, and the Lean Lexicon uses standardized work. Leader standard work is something else: a routine for supervisors and managers.
A standard work chart shows the layout of the area, the numbered work sequence, the walking path, takt time, cycle time, the standard in-process stock and the safety and quality checks. A combination table adds the manual, walking and machine time for each task drawn against takt time.
Standard work is designed around takt time for a repeating operator cycle and fixes the sequence and the stock in process. An SOP is the approved procedure for any controlled activity, with purpose, scope, responsibilities and steps, and it does not need a takt time.
Six steps: work out takt time, watch the job and list the tasks, time each one over several cycles, draw the combination table against takt, set the standard stock and draw the chart, then train, post and audit. Do the first three standing at the job with the operator, not at a desk.
When a better method is found, when demand changes takt, and whenever the audit shows the paper no longer matches the job. The Lean Lexicon describes standardized work as the object of continuous improvement through kaizen, so the standard is expected to change. A chart dated three years ago deserves a look.
Where there is no repeating cycle. A changeover or a repair is better served by an SOP or a checklist, because standard work needs a takt time and a repeating sequence to pace. Use it for repetitive operator work in a cell or on a line.
Without a written current method, nobody can show that a change made the job better, because there is nothing fixed to compare it with. The Lean Lexicon lists the baseline for improvement among what a plant gets from standardized work.
The team leader or supervisor with the operators who do the job, often with an engineer for the timing. People who do the work know which motions are awkward, and they are the ones who have to follow the result.
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