Template · Industrial engineering
Time study calculator: observed, normal and standard time
Turns stopwatch readings into normal and standard times, with the cycles needed for a set accuracy.
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XLSXCSVODSXMLNumbers| Time study calculator: observed, normal and standard time | |||||||||||
| Example data — replace the blue input cells with your own. | |||||||||||
| STANDARD TIME PER CYCLE (S) | PARTS PER HOUR | PARTS PER SHIFT | |||||||||
| 41.52 | 86.7 | 650 | |||||||||
| Operation and study settings | |||||||||||
| Operation name | Hand assembly of a cable clamp | ||||||||||
| Units per part | 1 | Cycles of the work needed to make one finished part. Use 1 when one cycle makes one part. | |||||||||
| Shift length (min) | 480 | Paid time in the shift | |||||||||
| Breaks and planned delays per shift (min) | 30 | Removed from the shift before the parts-per-shift count | |||||||||
| Confidence z-value | 1.96 | 1.96 gives 95% confidence. Use 1.645 for 90%. | |||||||||
| Accuracy target (plus or minus, share of mean) | 5% | Half-width of the confidence interval as a share of the mean observed time | |||||||||
| Work elements (times in seconds) | |||||||||||
| Work element | Performance rating | Cycle 1 | Cycle 2 | Cycle 3 | Cycle 4 | Cycle 5 | Cycle 6 | Cycle 7 | Cycle 8 | Cycle 9 | Cycle 10 |
Showing the first 16 of 37 rows and 12 of 18 columns. Cells with formulas show the formula on hover.
| Allowances for personal needs, fatigue and delay | ||
| Allowances added to normal time to reach standard time. The values are typical starting points; set each one for the job being studied. | ||
| PF&D allowances (share of normal time) | ||
| Allowance | Share used | Typical value and note |
| Personal needs | 5% | Typical value: 5%. Set it from the job's personal-needs pattern. |
| Basic fatigue | 4% | Typical value: 4%. |
| Standing | 2% | Typical value: 2%. Use it when the work is done standing. |
| Abnormal position | 0% | Typical value: 0%. Raise it for bending, reaching or cramped postures. |
| Lighting, noise and monotony | 2% | Typical range: 0% to 2%. Use the upper end for poor conditions or very repetitive work. |
| Delay (unavoidable) | 3% | Typical value: 3%. Use it for delays the operator cannot avoid, such as waiting for material. |
| Total allowance | 16.0% | |
| These are typical published allowance values, for example in ILO work study material. Set each one for the actual job and method. |
Showing the first 14 of 14 rows and 3 of 3 columns. Cells with formulas show the formula on hover.
| Time study calculator: observed, normal and standard time |
| Notes: what this workbook does, how to use it and the method behind it. |
| What it does |
| Turns stopwatch readings for up to eight work elements into mean observed time, normal time and standard time per cycle, then into standard minutes per part and parts per shift. |
| The Allowances tab holds the personal, fatigue and delay (PF&D) allowances. Their total is added to normal time. |
| The example data is fictional: six elements of a hand assembly, ten cycles each. The third element shows the flag for too few cycles. |
| How to use it |
| 1. On the Study tab, enter the operation name, units per part, shift length and breaks and delays. |
| 2. Enter the performance rating for each element as a percentage, such as 95% or 110%. |
| 3. Type up to ten observed cycle times in seconds for each element. Leave unused cycles blank. |
| 4. Set the confidence z-value and the accuracy target. Read the cycles required and the Status column. |
| 5. Set each allowance on the Allowances tab for the job, then read standard time and parts per shift. |
| Formulas and method |
Showing the first 16 of 36 rows and 1 of 1 columns. Cells with formulas show the formula on hover.
What does this template do?
A time study records how long each element of a manual task takes over repeated cycles. This workbook is for industrial engineers and supervisors who set standard times for an operation and need to know how many parts a shift can make.
Each element has up to ten observed cycle times in seconds and a performance rating. The sheet works out the mean observed time and the sample standard deviation, then normal time as mean times rating. Standard time per cycle is normal time multiplied by one plus the total allowance from the Allowances tab. Standard minutes per part, parts per hour and parts per shift follow from it.
For each element the sheet also computes the cycles required for the confidence z-value and accuracy target, and flags any element that was observed for fewer cycles. The example data is fictional: six elements of a hand assembly.
What’s inside
- Mean, sample standard deviation and normal time for up to eight work elements
- Standard time = normal time x (1 + allowance), with allowances on their own tab
- Cycles required per element from the z-value and accuracy target
- Standard minutes per part, parts per hour and parts per shift
- Flags elements that were observed for fewer cycles than required
Which tabs does the workbook have?
| Tab | What it holds |
|---|---|
| Study | Operation settings, element readings, ratings and the standard time build-up. |
| Allowances | PF&D allowance inputs with typical values and their total. |
| Notes | What the workbook does, the formulas in words, assumptions and limits. |
What formulas does this template use?
This template holds 64 formulas in 251 cells across 3 tabs, so 25% of its cells calculate. They use 10 distinct functions; the longest formula is 148 characters and 1 of them read from another tab.
| Function | Uses | What it does |
|---|---|---|
IF | 99 | one result when a test is true, another when false |
OR | 24 | true when any test is true |
SUMPRODUCT | 9 | multiplies matching entries, then adds them |
AVERAGE | 8 | mean of numbers |
COUNT | 8 | counts numeric cells |
ISNUMBER | 8 | true for a number |
ROUNDUP | 8 | rounds away from zero |
SQRT | 8 | square root |
SUM | 3 | adds numbers |
ROUNDDOWN | 1 | rounds toward zero |
Counted from the workbook itself. Only functions that Excel, LibreOffice Calc, Google Sheets and Apple Numbers evaluate the same way are used, so the formulas survive every download format.
How do you use it?
- Enter the operation name, units per part, shift length and breaks and delays on the Study tab.
- Enter the performance rating for each work element as a percentage, such as 95% or 110%.
- Type up to ten observed cycle times in seconds for each element, and leave unused cycles blank.
- Set the confidence z-value and the accuracy target, then read the cycles required and the status of each element.
- Set each allowance on the Allowances tab for the job, then read standard time and parts per shift.
What is it good for?
- Setting standard times for a manual assembly operation
- Checking a changed work method against the time it was studied at
- Estimating parts per shift before a line is staffed
- Preparing a time study write-up for a process improvement report
Questions about this sheet
How many cycles should I time?
The Study tab computes the cycles each element needs for the z-value and accuracy target you enter. At 95 percent confidence and plus or minus 5 percent accuracy, an element whose standard deviation is 5 percent of its mean needs 4 cycles.
What is the difference between normal time and standard time?
Normal time is the mean observed time multiplied by the performance rating, which adjusts for pace. Standard time adds the allowances to normal time.
Are the allowance values required?
No. The values on the Allowances tab are typical starting points, such as those found in ILO work study material. Set each one for the job being studied.
Which standard deviation does the sheet use?
It uses the sample standard deviation, with n minus 1 in the denominator. Blank readings are left out of the calculation.