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Stamp Calculator

Find out exactly how many Forever stamps you need for any letter, postcard, or large envelope.

Standard letter with 1-4 sheets is about 1 oz.
Approximate, using 20 lb paper + envelope.
Accuracy note: Large-envelope additional-ounce pricing assumes the standard $0.29 per extra ounce. Based on USPS retail prices, temporary holiday prices in effect October 4, 2026 through January 17, 2027 (USPS Notice 123, checked October 7, 2026). Letter and stamp prices are not affected.

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