files/en-us/web/api/htmlmeterelement/optimum/index.md
{{ APIRef("HTML DOM") }}
The optimum property of the {{DOMxRef("HTMLMeterElement")}} interface represents the optimum boundary of the {{htmlelement("meter")}} element as a floating-point number. It reflects the element's optimum attribute, or the midpoint between min and max values if not defined. The value of optimum is clamped by the min and max values.
This property can also be set directly, for example to set a default value based on some condition.
A number. Defaults to the midpoint between {{DOMxRef("HTMLMeterElement.min")}} and {{DOMxRef("HTMLMeterElement.max")}} if not defined.
In this example, no optimum value is set.
<label for="review">Star rating:</label>
<meter id="review" min="0" max="10" low="2" high="8" value="9"></meter>
Though not explicitly defined, the default optimum is the midpoint between min and max, but can be set to any value between min and max, inclusive.
const meterElement = document.getElementById("fuel");
console.log(meterElement.optimum); // 5
meterElement.optimum = (meterElement.max + meterElement.optimum) / 2;
console.log(meterElement.optimum); // 7.5
{{Specifications}}
{{Compat}}