Commentators explain that this verse establishes a fair, prorated system for valuing a dedicated field. If a field was vowed to God after a Jubilee year had begun, its value was calculated based on the number of years remaining until the next Jubilee. For each year that had already passed, a portion of the value was deducted, reflecting the diminished time the sanctuary would benefit from the land. This demonstrates God's concern for fairness and practicality in our giving.