TAHA Engineering Toolsby TAHA Knowledge Lab

Industrial & Manufacturing

Standard Time Calculator (Time Study)

Normal time and standard time from a time study: observed time, rating and allowances.

Inputs

Three bars: observed time; normal time equal to observed time times rating; standard time equal to normal time plus allowances.Observed time (stopwatch average)Normal time = observed × ratingStandard time = normal time + allowances+ allowancesstandard time
The observed time is adjusted by the performance rating to give the normal time (here 110%, so it gets longer). Adding allowances for personal needs, fatigue and delays gives the standard time. Diagram not to scale.

Average of your stopwatch readings for one cycle of the job.

100% = normal pace of a qualified worker. Above 100% means the observed worker was faster than normal.

Check which method your company or textbook uses — they give slightly different answers.

Used only for output per shift.

Result

Standard time per cycle
2.53
Normal time per cycle
2.2
Standard output per hour
23.7154cycles/hour
Standard output per shift
189.723cycles/shift

A qualified worker at normal pace needs 2.2 min per cycle. Adding allowances gives a standard time of 2.53 min, or about 23.7154 cycles/hour.

Educational estimate — check the assumptions below.

About this calculator

Standard time is the time a qualified worker needs to do a job at a normal pace, including fair allowances for personal needs, fatigue and unavoidable delays. It is used to plan capacity, balance lines, set staffing and calculate labour cost. It is found by time study: observe the job, rate the worker’s pace, then add allowances.

Formula

Normal time = Observed time × Rating

Standard time = Normal time × (1 + Allowance)  or  Normal time ÷ (1 − Allowance)

Rating and allowance are used as decimals (110% = 1.10; 15% = 0.15). The first form treats allowances as a percentage of normal time; the second as a percentage of total working time.

Worked example

Observed average time 2.0 min, rating 110%, allowances 15%:

  • Normal time = 2.0 × 1.10 = 2.20 min
  • Standard time (allowance on normal time) = 2.20 × 1.15 = 2.53 min → 60 ÷ 2.53 = 23.7 cycles per hour
  • Standard time (allowance on working time) = 2.20 ÷ 0.85 = 2.59 min

Assumptions and limitations

  • The observed time should be an average of enough readings to be representative, with abnormal readings removed.
  • Performance rating needs a trained observer; it is a judgement, not a measurement.
  • Allowance percentages vary by company, task and working conditions. Use your organisation’s agreed values.

References

  • ILO, Introduction to Work Study; Freivalds & Niebel, Methods, Standards, and Work Design.