Filter change alert system for an HVAC system

Methods and systems for indicating a status of an air filter of an HVAC system may include receiving a measure that is related to an amount of flow restriction presented by the air filter in an HVAC system, using the measure to determine whether the air filter does not need replacing, the air filter needs to be replaced soon, or the air filter should be replaced now, and displaying on a display of an HVAC controller an air filter status indicator, wherein the air filter status indicator includes a stop-light metaphor. In one example, the air filter status indicator may display a green color when the air filter does not need replacing, display a yellow color when the air filter needs to be replaced soon, and display a red color when the air filter should be replaced now. In some cases, the air filter status indicator may also include a qualitative term indicative of the current status of the air filter.