Time Study

A time study is the direct observation and measurement of a specific task divided into discrete work elements across multiple cycles. Using a continuous timing method with a stopwatch, observers document exact step durations, separate human effort from machine time, and flag process abnormalities. Rather than calculating an arithmetic average, lean methodology determines the lowest repeatable time for each element. This data establishes the baseline for standard work, line balancing against takt time, and eliminating non-value-added waste during continuous improvement.

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Ten cycles, one stopwatch

Key facts

Originator: Frederick Winslow Taylor (1880s–1890s)
Timing method: Continuous timing
Baseline metric: Lowest repeatable time
Primary applications: Standard work, line balancing, and waste reduction
Abnormality handling: Flagged and excluded from baseline calculations

By Matthew Savas — Founder of Kaizumi. Reviewed 1 September 2026.

A time study is the direct observation and timing of a specific job, divided into discrete work elements, across multiple work cycles to determine the repeatable time required to complete the task under normal conditions. In lean manufacturing and operational management, observers record individual work steps using a continuous stopwatch method to isolate standard work content from random abnormalities, delays, and waste. The data collected during a time study serves as the empirical foundation for designing standard work, balancing production lines against takt time, and identifying opportunities for targeted process improvement.

History and origin

Work measurement through direct timing began with the scientific management studies conducted by Frederick Winslow Taylor in the 1880s and 1890s. Taylor analyzed industrial tasks by breaking complex jobs down into basic manual motions, timing each component separately with a stopwatch, and eliminating unnecessary physical movements. This practice established the field of industrial engineering work measurement.

During the mid-twentieth century, Toyota adapted these industrial engineering principles into the Toyota Production System. Rather than using time studies strictly to set individual labor quotas or piece rates, lean practitioners used time observation to understand process capacity, identify work sequence irregularities, and establish consistent baselines for continuous improvement. The modern lean time study emphasizes the direct observation of work where it takes place, documenting the actual motion sequences of operators and separating human work time from machine processing time.

Purpose and core principles

The primary objective of a time study in a lean system is to establish standard cycle times based on achievable, repeatable operator performance. The data gathered provides an objective basis for several core operational functions:

Establishing standard work: By defining the baseline duration for each discrete step in a process, operations can construct standardized work combination sheets and operator instruction sheets.
Line balancing: Individual element durations are compared against takt time to distribute labor evenly across workstations using a yamazumi chart.
Identifying waste: The detailed breakdown of physical steps highlights non-value-added activities, such as excessive operator walking, repositioning of materials, and process waiting times.
Quantifying improvement: Before-and-after time observations measure the precise impact of changes made during a kaizen event.

Lean time studies adhere to specific observation principles. The observer must watch multiple full cycles of work from a physical vantage point where both the operator's hands and the material flow are clearly visible. The work must be divided into clearly bounded elements with recognizable start and stop points, and the observer must record every deviation or interruption as an abnormality rather than blending delays into the standard baseline.

Observation methodology

Conducting an accurate time study requires structured preparation, consistent execution during data collection, and systematic calculation following the study. Observers use a standardized time observation sheet to capture both continuous elapsed times and detailed step descriptions.

Try it yourself

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You can use the time study template to record individual cycle times, track element variations, and calculate repeatable work baselines.

Step 1: Element definition

Before starting the stopwatch, the observer documents the sequence of work by splitting the job into distinct elements. Each element must represent a logical segment of work with an observable beginning and ending point, often signaled by an audible cue or a distinct physical movement, such as setting down a tool or grasping a component.

Elements are named on each row of the observation sheet using plain descriptive language rather than abstract codes. An element should read "walk to shelf, get parts" or "tighten four housing bolts" rather than "element 1" or "process step A." Naming elements concretely ensures that any observer can identify the exact motion being measured and spot procedural drift between different cycles.

Step 2: Continuous timing

Lean methodology uses the continuous timing method rather than the snapback method. In continuous timing, the stopwatch starts at the beginning of the first element of the first cycle and runs continuously without being reset until the final element of the last cycle is complete.

When the operator completes an element, the observer records the current running total displayed on the stopwatch in the raw time column. After the study is finished, the observer calculates individual element times by subtracting the previous element reading from the current element reading. The continuous method prevents timing errors caused by mechanical delay in resetting the watch, ensures that no unaccounted time disappears between elements, and accounts for all elapsed time on the production floor.

Step 3: Flagging abnormalities

If an abnormal event occurs during a cycle, the observer notes the reading, flags the entry with an indicator, and writes the specific root cause in the notes column. Abnormalities include events such as dropping a tool, clearing a machine jam, retrieving missing hardware, or speaking with a supervisor. These entries are excluded when determining the baseline standard time, as standard work must reflect the process when the work proceeds without failure.

Step 4: Determining the lowest repeatable time

To set the standard work baseline, lean methodology uses the lowest repeatable time for each element rather than the arithmetic average. The observer reviews all recorded times for a single element across the clean, unflagged cycles and selects the lowest duration that occurred more than once.

The lowest repeatable time demonstrates the time required to complete the manual motion when the operator encounters no resistance, delays, or physical micro-stoppages. Arithmetic averages automatically incorporate random variation, operator hesitation, and minor friction into the standard, which hides operational waste. If an unusually fast time occurs only once in the entire sample, it is disregarded because it has not demonstrated repeatability.

Worked example: valve assembly cell

The following worked example illustrates a complete ten-cycle time study conducted on a manual valve assembly station. The process consists of four defined elements observed across ten consecutive cycles.

Process elements

Walk to shelf, get parts: Operator walks to the storage rack, selects one valve body and two seals, and returns to the workbench.
Assemble valve: Operator places the body into the fixture, inserts the seals, aligns the stem, and fastens the retention collar.
Test valve: Operator connects the assembled valve to the pneumatic test port, runs the pressure check, and verifies the gauge reading.
Pack valve: Operator disconnects the valve from the tester, places it into the shipping dunnage, and marks the routing tag.

Observation data across ten cycles

The observer maintained a continuous stopwatch throughout the observation. The stopwatch read eight minutes and one-tenth of a second (8:00.1) at the completion of the tenth cycle. Subtracting consecutive continuous stopwatch readings generated the following individual element times in seconds:

Walk to shelf, get parts: 9.4, 9.0, 9.8, 9.1, 9.0, 12.6, 9.3, 9.0, 9.6, and 9.2 seconds. In cycle six, the reading reached 12.6 seconds because the operator dropped a seal on the floor. This cycle was flagged as an abnormality. The lowest time that repeats is 9.0 seconds, which occurred three times across the ten cycles (in cycles two, five, and eight).
Assemble valve: 22.8, 22.0, 23.5, 22.3, 22.0, 22.9, 26.1, 22.0, 22.6, and 22.4 seconds. In cycle seven, the duration was 26.1 seconds because the assembly fixture jammed during clamping. This cycle was flagged as an abnormality. The lowest time that repeats is 22.0 seconds, which occurred three times (in cycles two, five, and eight).
Test valve: 10.4, 10.0, 10.9, 10.0, 10.3, 10.0, 10.7, 10.2, 10.0, and 10.5 seconds. No process abnormalities occurred during testing. The lowest time that repeats is 10.0 seconds, which occurred four times (in cycles two, four, six, and nine).
Pack valve: 5.3, 5.0, 5.6, 5.0, 5.2, 5.0, 5.9, 5.1, 5.0, and 5.4 seconds. No abnormalities occurred during packing. The lowest time that repeats is 5.0 seconds, which occurred four times (in cycles two, four, six, and nine).

Baseline calculation

The standard cycle time is calculated by adding together the lowest repeatable time of each element:

Walk to shelf, get parts: 9.0 seconds
Assemble valve: 22.0 seconds
Test valve: 10.0 seconds
Pack valve: 5.0 seconds

Adding these four element values produces a total lowest repeatable cycle time of 46.0 seconds.

Of the total 46.0-second baseline, 9.0 seconds consists entirely of walking back and forth between the workbench and the parts shelf. This walking time represents pure motion waste. In an upcoming kaizen event, the improvement team can target this 9.0-second element for elimination by relocating the storage bins directly onto gravity flow racks within the operator's primary reaching zone.

Lowest repeatable time versus average time

Using the mathematical average of an element introduces distortion into standard work calculations. In the worked example above, calculating the simple average for the walking element across all ten cycles yields 9.60 seconds. Even if the flagged abnormality of cycle six (12.6 seconds) is removed, the remaining nine clean cycles produce an average of 9.27 seconds.

The average is inflated by normal human variance, slight posture adjustments, minor visual searches, and pacing differences. The lowest repeatable time of 9.0 seconds represents a demonstrated capacity: the operator proved across three separate cycles that the physical task requires exactly 9.0 seconds when no resistance occurs.

The repetition requirement protects the standard from unrepresentative anomalies. If an operator completed the walk in 8.6 seconds on a single cycle by cutting across an unsafe pathway or rushing in an unsustainable manner, that 8.6-second reading would be discarded because it was not demonstrated repeatedly. The standard must reflect sustainable, repeatable work.

Applications in industry

Time studies apply to manual and semi-automated work across diverse operating environments.

Manufacturing

In an industrial manufacturing cell, time studies distinguish between manual operator time, machine automatic cycle time, and component transfer time. For example, a study of a valve assembly workstation over ten cycles established a lowest repeatable manual cycle of 46.0 seconds, isolating 9.0 seconds of walking waste from the 37.0 seconds of direct assembly, testing, and packing work. This separation allows engineers to design point-of-use material presentation that cuts cycle time without requiring the operator to work at a faster pace.

Healthcare

In hospital pharmacies, central sterile processing departments, and outpatient clinics, time studies measure administrative and preparation steps. An observation of an intravenous medication compounding process breaks down the work into gowning and sanitizing, gathering medication vials, scanning bar codes, reconstituting the mixture inside a laminar flow hood, and labeling the final product. Recording lowest repeatable times identifies delays caused by poorly organized supply carts or software lag, allowing hospitals to reduce medication turnaround times.

Logistics and distribution

In distribution centers, time studies measure order picking, packing, and sorting routines. Observers break down picking cycles into reading the digital scanner, traveling to the pick location, verifying the bin location, grasping the inventory item, and confirming the quantity. The study isolates travel duration from physical handling time, providing the baseline metrics required to optimize warehouse slotting layouts and conveyor transfer points.

Common observation errors

Reliable time studies depend on rigorous observation hygiene. Common operational errors during time studies include:

Grouping distinct tasks into broad elements: Combining "retrieve parts," "assemble housing," and "fasten bolts" into a single sixty-second element obscures where variation occurs and prevents targeted elimination of waste.
Using the snapback timing method: Resetting the watch to zero at every element boundary introduces mechanical timing errors and encourages the observer to round numbers or ignore transition pauses.
Including abnormal cycles in standard baselines: Blending equipment jams, dropped parts, or interruptions into the baseline time generates an artificially long cycle time that normalizes operational defects.
Measuring unstandardized work: Attempting to time an operation while operators use different work methods, tool sequences, or workstation layouts yields unusable, non-repeatable data. The work method must be standardized before baseline timing begins.

Frequently asked questions

Why does a lean time study use the lowest repeatable time instead of an average?: Calculating an arithmetic average automatically incorporates operator hesitation, pacing differences, and minor friction into the standard, which conceals operational waste. Selecting the lowest time that occurs more than once proves that the duration is realistic and achievable without disruption. Requiring the time to repeat also protects the baseline from unrepresentative anomalies, such as an unsustainably rushed cycle that cannot be safely maintained.
Why is the continuous timing method used instead of the snapback method?: In the continuous method, the stopwatch runs uninterrupted from the start of the study to the end, and the observer records running totals before subtracting them later. The snapback method resets the watch to zero at every step, which introduces mechanical delays and allows unaccounted time to disappear between tasks. Continuous timing guarantees that all elapsed time on the production floor is captured without rounding errors.
How are process abnormalities handled during a time study?: When an interruption occurs—such as a dropped part, a machine jam, or a conversation with a supervisor—the observer flags the entry and records the root cause in the notes. These abnormal cycles are excluded when determining the baseline time because standard work must reflect normal operations without failure. Blending delays or equipment defects into the baseline calculation artificially inflates standard cycle times and normalizes process waste.
How should work elements be defined before timing begins?: The observer divides the total task into distinct manual steps with recognizable start and stop points, often signaled by audible cues or physical motions such as releasing a tool. Each element is given a descriptive name, such as 'walk to shelf, get parts,' rather than a vague code. Dividing the work into discrete, identifiable steps prevents multiple activities from being grouped together and allows observers to locate exactly where variation occurs.
How does the lean approach to time studies differ from Taylor's scientific management?: Frederick Winslow Taylor developed time studies in the 1880s and 1890s to set individual labor quotas and piece rates by timing basic manual movements. In the mid-twentieth century, the Toyota Production System adapted the technique to evaluate process capacity, isolate human work from machine time, and expose waste. Instead of enforcing individual speed quotas, lean time studies provide an objective baseline for line balancing and continuous improvement.

Terms

Cycle Time Kaizen Event Standard Work Takt Time Yamazumi

Tools and simulations

Time study template