Holt-Winters
Calculate Holt-Winters instantly with the exact formula and a worked example.
Holt-Winters
Previous level (L)
Previous trend (T)
Seasonal term for this period (one season ago)
Current actual value
Seasonal term for next period
α (level)
β (trend)
γ (seasonality)
Next-period forecast
100.44
New level (L)
103.20
New trend (T)
2.24
New seasonal term (S)
10.54
More about: Holt-Winters
What it calculates
The “Holt-Winters” calculator computes Next-period forecast from 8 parameters: previous level (l), previous trend (t), seasonal term for this period (one season ago), current actual value, seasonal term for next period, α (level), β (trend), γ (seasonality).
A handy everyday calculator for daily tasks.
Example calculation
With parameters Previous level (L) = 100, Previous trend (T) = 2, Seasonal term for this period (one season ago) = 10, Current actual value = 115, Seasonal term for next period = -5, α (level) = 0.4, β (trend) = 0.2, γ (seasonality) = 0.3 the result is 100.44 (Additive model, single update step).
How to use
- Enter previous level (l), previous trend (t), seasonal term for this period (one season ago), current actual value, seasonal term for next period, α (level), β (trend) and γ (seasonality) — each field above is adjustable with a slider.
- Next-period forecast is calculated automatically as you type.
- Check the worked example below to see the formula applied to real numbers.
- Copy the result or bookmark this calculator.
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FAQ
How is Holt-Winters calculated?
The Holt-Winters calculator computes Next-period forecast from previous level (l), previous trend (t), seasonal term for this period (one season ago), current actual value, seasonal term for next period, α (level), β (trend), γ (seasonality). Enter your values above and the exact formula is applied instantly; a worked example with real numbers is shown below.
Is the Holt-Winters calculator free?
Yes. It is completely free, needs no signup, runs entirely in your browser, and sends no data to any server.
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