Manufacturing Time Study: Set a Usable Standard Time

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A manufacturing time study measures defined work so you can establish how long it should take under stated conditions. In a direct stopwatch study, you divide the work into elements, observe their durations, account for normal working pace where relevant, and include justified allowances to form a standard time.

The important word is defined. An average of last month’s job bookings may mix different methods, material shortages and learning time. Timing your fastest operator gives you a different number, but not necessarily a better standard.

A useful study leaves you with a time you can explain, validate and update when the work changes. SkyPlanner then helps you put realistic operation durations to work across the order backlog, rather than correcting a number in the ERP and rebuilding every affected machine queue by hand.

Observed time, normal time and standard time

These three numbers answer different questions:

Time	What it means	What must be known
Observed time	How long the recorded work actually took	The method, timing boundaries and conditions during observation
Normal time	Time for the defined work at the reference working pace	A justified performance rating for pace-dependent manual work
Standard time	Normal time with the applicable allowances included	Which allowances apply and how they are calculated

A standard time is not a speed record. It represents a defined method performed by a trained, proficient person at the reference pace, with the necessary allowances.

Nor is a labour standard automatically the time a machine must be reserved. A machine may run while its operator inspects the previous part. Keep that distinction visible throughout the study: you are establishing the work content before deciding how it loads each resource.

Choose the measurement method for the work

A direct stopwatch study suits stable, repetitive work whose elements you can observe. It is a good choice when you need to understand why an existing standard is wrong, not simply replace it with another estimate.

Other situations call for a different approach:

• Similar jobs reuse known elements. A validated standard-data system can combine established element times, provided the method and influencing factors match. Do not pool unlike products into one average.
• The manual method is being designed before production starts. A predetermined motion time system can build the time from defined movements. This requires trained application of the chosen system, rather than guessing a stopwatch rating.
• You need to understand where a shift goes. Work sampling estimates the share of time spent on activities or delays. It can support allowance assessment, but does not by itself give you the detailed time of each short work element.
• The process controls the duration. Calculate or verify machine time from the program or process parameters, and study the operator’s work separately.

Historical job records remain useful evidence. Check what they include before treating them as a standard: an elapsed booking that contains a missing-material wait cannot tell you the normal manual work content on its own.

The following method focuses on a direct study of repetitive work.

1. Define the method before starting the clock

Select an operation where a more credible standard will change a real decision: a heavily loaded assembly station, for example, or a repeat job whose duration regularly surprises planning.

Describe the product and revision, equipment, tooling, material presentation, work sequence and required quality checks. State the start and finish events. Make clear whether the result is per piece, per cycle or per batch, and keep one-off setup identifiable.

Work through that description with the people doing the operation. Explain why the study is being made and how the results will be used. Their knowledge often reveals essential work that an existing estimate leaves out, such as replenishing a fixture or making a periodic check.

Observe a trained operator using the established, safe method. If the fixture is still being redesigned or the operator is still learning the sequence, first stabilise the method. More stopwatch readings will not make an unsettled process into a reliable standard.

2. Record elements, frequencies and exceptions

Break the operation at clear, observable events: housing seated in fixture, fasteners tightened, inspection completed. Separate pace-dependent manual work from machine-controlled time. Record work that happens only occasionally, such as a container change, with its frequency rather than pretending it occurs on every piece.

For each observation, retain the element time, relevant conditions and any performance rating used. Note interruptions when they occur. If a component is missing or a tool breaks, record the event and its duration separately; do not silently delete the long reading or bury it in the normal work average.

Collect observations across representative production, not just one convenient uninterrupted run. Check whether the same method and conditions produce reasonably consistent element times. If they do not, investigate the cause: different material presentation may need a separate method, while an occasional measurement error needs a documented correction.

There is no universal number of cycles that makes a study sufficient. The observation count depends on variability, the precision needed and the decision the standard will support. Use an initial set to assess the spread, then set the required sample size using the chosen confidence and precision criteria. A trained work-measurement analyst can make that assessment. Ten near-identical readings from one unusual run are not a substitute for representative evidence.

3. Convert manual observations to normal time

For each element, calculate a representative observed duration from comparable readings, commonly their arithmetic mean. Keep the reasons for excluding any reading. If pace differs between observations, normalise the corresponding readings before combining them rather than applying an unrelated average rating.

Performance rating compares the observed manual working pace with a defined reference pace. Using a scale where normal pace is 100%, the calculation is:

Normal manual time = observed manual time × rating factor

A rating of 110% is a factor of 1.10. It means the observed work was faster than the reference pace, so its normal time is longer than the observed time. A rating below 100% produces the opposite adjustment.

Rating is not a percentage chosen to make the result match the old ERP standard. It needs a trained assessor, a consistent reference and an assessment made while observing the work. If you cannot justify the rating, retain the result as an observation rather than presenting it as a normal-pace standard.

Apply the rating to the relevant manual elements, not indiscriminately to the whole elapsed operation. An automatic three-minute heating cycle does not become longer because the person loading it worked at 110%. Where pace changes between observations, preserve the corresponding time and rating together so the calculation reflects what was actually observed.

4. Add allowances on an explicit basis

Normal work time alone does not cover every legitimate demand on a working day. Personal needs, recovery from the work and applicable unavoidable delays need appropriate treatment.

Determine those allowances from the job’s conditions, the work-measurement method being used and evidence of the activities or interruptions concerned. Broader observation or work sampling can help establish recurring support and delay time; recovery needs require an assessment of the work and conditions. A percentage copied from another factory is not that assessment.

Keep required occasional work in view. If a regular container change has already been included as an element, do not charge for it again in a general delay allowance. Equally, do not convert every avoidable breakdown or missing-material wait into permanent work content. Record those losses so they can be addressed, and make their treatment in planning explicit.

Worked example: from observations to a standard

Imagine a stable manual assembly operation. The following figures illustrate the calculation; the rating and allowance are not recommendations for your factory. Assume the listed elements occur sequentially, once per assembly, and the analyst has justified a 110% rating for the observed manual work.

Manual element	Selected observed time	Rating factor	Normal time
Fit the housing	30 seconds	1.10	33 seconds
Fasten the assembly	40 seconds	1.10	44 seconds
Inspect and place in tray	20 seconds	1.10	22 seconds
Repeating work total	90 seconds		99 seconds

There is also a required container change every 20 assemblies. Its separately established normal time is 60 seconds, so its contribution is 60 ÷ 20 = 3 seconds per assembly. Total normal work content is therefore 102 seconds per assembly.

Now suppose the study establishes an allowance equal to 15% of normal time:

Standard time = normal time × (1 + allowance)

102 × 1.15 = 117.3 seconds per assembly.

The denominator matters. If an allowance is instead expressed as 15% of total standard time, use:

Standard time = normal time ÷ (1 − allowance)

102 ÷ 0.85 = 120 seconds per assembly.

Those results differ because “15%” describes two different ratios. Record which basis your standard uses. A future planner should not have to reverse-engineer it from the final number.

5. Validate and release a standard you can maintain

Before replacing the current standard, check the result against further runs using the same method and conditions. Compare equivalent quantities and time boundaries, including the periodic work and allowances that the standard covers. One cycle finishing below an allowance-inclusive standard is not evidence that the allowance should disappear.

Review unexplained differences with the operator and the person responsible for the method. If the result fails because an essential element is missing, correct the study. If the method varies, define the variants. Do not simply increase the standard until every historical booking fits.

Keep a traceable record with:

• The product, operation, method revision and resource conditions covered.
• The original observations, element frequencies and treatment of exceptions.
• The rating convention, assessment and calculation of normal time.
• The allowance categories, evidence, denominator and resulting standard.
• The validation result, responsible reviewer, effective date and review triggers.

Release the standard through your production-engineering approval process. Approval confirms that the evidence and scope are suitable for use; it does not replace measurement with a negotiated number.

Revisit the standard when tooling, material, design, inspection requirements or the working method changes, and when comparable actuals show a persistent unexplained difference. Preserve the previous version so you can distinguish a genuine method improvement from a change in how time is recorded.

Turn the standard into the right resource load

Before entering the result into a scheduling model, ask: what is this time reserving?

In the all-manual example, the standard describes assembly work at one station. In a machining operation, operator work, automatic running and inspection may overlap. Adding them all together would overstate elapsed machine occupancy; using cutting time alone could omit loading that prevents the next cycle from starting.

Draw the operator and machine activities on parallel timelines when overlap matters. Establish when each resource is occupied, and whether the operator can actually serve another job during automatic running. Do not assume unattended running means unlimited operator availability.

Also reconcile allowances with the resource calendar. A break already removed from available working time should not reduce capacity a second time through a duration allowance for the same break. Preserve the study’s standard, but document how its components become the planning duration and available capacity.

For time-per-piece calculations and scaling setup separately across different order quantities, use our manufacturing cycle time guide. The decision here is earlier: whether the underlying standard represents the defined work at all.

Put better durations to work with SkyPlanner

A corrected duration matters beyond the operation you studied. It changes the space needed in a machine queue, when downstream work can start and how other orders compete for the same capacity. Updating one master-data value is only the beginning of that planning work.

SkyPlanner lets you define process-step durations, setup and teardown times, eligible workstations and dependencies. Arcturus, its scheduling AI, calculates the production schedule against your configured resources and priorities, and the Gantt view shows the result. You can review the consequences of more realistic durations across the backlog instead of manually rebuilding each affected queue. You set the priorities and protect decisions with rules and locks.

SkyPlanner’s Timer and ShopFloor tools support time and quantity recording, giving you actual production evidence for subsequent reviews. It also offers process-step duration prediction from historical time logs. That helps you keep planning estimates connected with experience. The study answers what the defined work should require at normal pace; historical prediction helps estimate duration from recorded production. Keep those purposes distinct when deciding which input to use.

Mamec’s experience shows why coordinated scheduling matters. The Finnish manufacturer had thousands of interdependent work orders, with priorities managed from delivery dates on paper orders. SkyPlanner was integrated with its Oscar ERP and became the main production-planning platform. Mamec reports a shared real-time production view and a clearly lighter planning workload. Its story illustrates the value of managing the whole plan, rather than leaving each queue to a separate manual decision.

Choose SkyPlanner when better operation times need to become a better production schedule. It integrates with any ERP or MES through its open REST API, so you can retain your existing systems while bringing realistic durations into finite scheduling.

Book a SkyPlanner demo with one operation’s current standard, its study record, recent actuals and a typical order route. That gives you a concrete starting point for seeing how a justified time can improve the plan your shop follows. If you prefer to explore first, try SkyPlanner with demo data.