Margin utilization = ((Maintenance margin reserved) / (Account Value - Not available as margin collateral)) * 100
You can find your margin utilization percentage at Portfolio in SaxoTrader mobile app and expand Initial margin available.
Example:
10.3% ≈ (3,479.72 / (92,711.18-59,036.2)) * 100
Or you can find it at Trading > Summary.
Your account value with extended hours may be different from normal account value. Read more on extended hours trading.