Study & writing
Learning curve calculator
Enter how long the first unit took, pick a learning rate and a number of repetitions to see how the time per unit falls.
A lower learning rate means faster improvement. An 80% rate is a common default for assembly and manual tasks.
How the learning curve is calculated
Wright's learning-curve model says that every time the cumulative number of units doubles, the time to make one unit falls to a fixed percentage of what it was — the learning rate. The time for unit n is: Tₙ = T₁ × n^b, where T₁ is the first-unit time and the exponent b = ln(rate) ÷ ln(2). An 80% rate gives b = ln(0.8) ÷ ln(2) ≈ −0.322. Cumulative time is the sum of T₁ × i^b for every unit i from 1 to n, and the average is that total divided by n.
Worked example: a first unit of 60 minutes at an 80% rate over 10 repetitions. The 10th unit takes 60 × 10^(−0.322) ≈ 29 minutes (28.6 before rounding). Adding every unit from 1 to 10 gives about 379 minutes in total, so the average is roughly 37.9 minutes per unit. The task has already sped up by more than half between the first repetition and the tenth.
| Learning rate | 10th unit (% of first) | 100th unit (% of first) |
|---|---|---|
| 70% | 31% | 9% |
| 80% | 48% | 23% |
| 90% | 74% | 55% |
Reading the rate and the numbers
A lower learning rate means a steeper curve and faster improvement, which is the opposite of what the percentage first suggests. At a 70% rate each doubling cuts the unit time to 70%, so by the 100th unit you are down to about 9% of the first; at 90% progress is slow and the 100th unit still takes more than half the original time. Aircraft manufacturing, where the concept was first measured in the 1930s, is often quoted near 80%, but the right rate depends on how much of the task can actually be automated or routinised.
Two cautions. First, the model describes repetitive, human-paced work — assembly, data entry, a practised routine — not creative or one-off tasks, and it eventually flattens as a physical or process floor is reached, so extrapolating to huge numbers of repetitions overstates the savings. Second, the first-unit time anchors everything; an unusually slow or fast first attempt skews the whole projection, so use a representative early figure rather than your very worst start. Used for estimating and pricing repeated work, the cumulative and average times are usually more useful than the single nth-unit figure.
Frequently asked questions
What is Wright's learning curve?
It is a model stating that each time production doubles, the time per unit drops to a set percentage of its previous value. An 80% curve means the unit time falls to 80% with every doubling.
What does an 80% learning rate mean?
It means that whenever the number of units doubles, the time to make one falls to 80% of what it was. Lower rates such as 70% improve faster; higher rates such as 90% improve slowly.
How do I calculate the time for the nth unit?
Multiply the first-unit time by n raised to the power b, where b = ln(rate) ÷ ln(2). For 60 minutes, an 80% rate and 10 units: 60 × 10^(−0.322) ≈ 29 minutes.