There is no definite answer to this question. How long any flag will last depends on the material it is made from, the weather, where you fly your flag, it's location with relation to other building, trees, etc., airborne contamination in the area, exposure to sun and how often you fly your flag.

You flag is a piece of fabric that works very, very hard for you. Through its lifetime your flag shakes, trembles, drapes, snaps, chafes, bakes, freezes, ripples, flutters, furls, twists, flaps, strains, flies, unfurls, and hangs. It is up there in fog, sun, rain, snow, sleet and hail. It flutters, waves, snaps and trembles no matter how wet, cold, frozen, hot or dry it is. Is it any wonder that a flag that flies continuously needs replacing two or three times a year or more often? Wind, water, sun, contamination and carelessness are the major enemies of a flag.

No one can control the weather but you can take important steps to lengthen the life of your flag.. Occasionally washing your flag in warm detergent and water will prevent pollutants and dirt from weakening the fabric and help lengthen its life. If you take down your flag, make sure it is dry and clean before storing it.  This will prevent mildew and color transfer. At the first sign of fraying, have your flag repaired before further damage is done.

Always keep your flagpole as clean as possible and move your pole if your flag does not have adequate room to fly unobstructed. If there are nearby trees, keep them trimmed so that they do not interfere with the flying of your flag. If your flag flies from a building or porch railing, make sure it cannot catch on rough parts of the building, roofing or nearby greenery. All of these protective measures will lengthen the life of your flag.

Enjoy your flag. Take pride in it and it will serve you well.