SMA, EMA and WMA: three ways to calculate a moving average

A moving average can be simple, exponential or weighted; they differ in how much weight recent prices get. Most brokers and charting software default to SMA.

Updated：2026-11-08

The default is SMA

In most brokers and charting software, a “moving average” defaults to the SMA (simple moving average), and so does this site: unless you pick otherwise, MA means SMA. EMA and WMA are two other methods; switch the “kind” in the MA settings on the Technical tab when you need them.

SMA: simple moving average

The arithmetic mean of the last N closing prices, every day weighted equally:

SMA = (C₁ + C₂ + … + C_N) ÷ N

For a 5-day SMA, add the last 5 closes and divide by 5; when a new day comes in, the oldest day drops out. It is the simplest and most universal definition, so different programs agree; the downside is that old and new prices count the same, so it reacts more slowly to recent changes.

EMA: exponential moving average

More recent prices get more weight, and the weights fall by a fixed ratio going back:

• Smoothing factor α = 2 ÷ (N + 1)
• EMA = α × today’s close + (1 − α) × previous EMA

EMA reacts faster than SMA; MACD uses the 12-day and 26-day EMAs. Because the formula reaches back indefinitely, how the starting value is chosen (for example the first close, or the SMA of the first N days) makes the early values differ slightly, so different programs may not match exactly.

WMA: weighted moving average

The weights of the last N days are 1, 2, …, N, with the most recent day weighing most:

WMA = (1 × C₁ + 2 × C₂ + … + N × C_N) ÷ (1 + 2 + … + N)

The weights rise linearly, so the speed usually sits between SMA and EMA, and both the calculation and the starting point are unambiguous; fewer people use it than SMA or EMA.

Which one to use

There is no “right answer”:

• All three lag: they describe prices that already happened and do not predict.
• The longer the period, the smaller the gap between the three; the shorter the period and the bigger the price swings, the more visible the gap.
• When you discuss moving averages with others or compare numbers with other software, first check which kind they use; when nothing is said, it usually means SMA.

Where to see it on this site

On a stock page, open the Technical tab, add MA and choose the kind (SMA, EMA or WMA) and the period; the screener’s moving-average conditions use SMA. Use adjusted prices, otherwise ex-dividend gaps distort the averages.

This article only explains the calculation. It is not investment advice.