MACD lab
See what MACD is built from, why its crossovers necessarily arrive after the move, and what the histogram is really telling you.
Runs entirely in your browser — nothing you type is sent anywhere. Educational only, and not investment advice.
How to use this calculator
Each step names a control you will find on screen above.
- Fast EMA and Slow EMA
The default 12 and 26. MACD is simply the gap between them, so it is positive when the short average is above the long one.
- Signal EMA
A 9-period average of the MACD line itself. The famous "crossover" is the MACD crossing this — an average of an average of averages.
- Read the histogram as acceleration
The bars are the gap between MACD and signal. Shrinking bars mean the move is losing momentum even while price still rises.
- Note when the crossover arrives
Mark the low on the chart, then find the bullish crossover. Count the sessions between them. That lag is structural and cannot be tuned away.
Worked example: Counting the lag
Standard settings. Find a clear bottom on the chart and count to the crossover.
What to enter
- Fast EMA
- 12
- Slow EMA
- 26
- Signal EMA
- 9
What it shows you
- MACD line
- 12-EMA minus 26-EMA
- Signal line
- 9-EMA of the MACD line
- Typical crossover lag
- 5–10 sessions after the turn
- Histogram turns
- Several sessions before the crossover
- Faster settings
- Less lag, far more false signals
Where this is taught
A calculator gives you a number. These explain what the number means and when it misleads you.