When mailing an envelope through the United States Postal Service (USPS), one of the most common questions that comes up is: Do I need to put one stamp or two stamps on the envelope? The answer depends on several factors, including the weight and dimensions of the envelope, the type of mail service used, and any additional services requested.
Quick Answer
For a standard letter-sized envelope weighing 1 oz or less, only one Forever stamp is needed when sending via regular First-Class Mail service within the United States. Heavier letters, large envelopes, and additional services like certified mail may require extra postage.
Standard Envelope Sizes and Weights
The most common envelope sizes used for mailing letters and documents are:
- Standard business envelopes: 9.5″ x 4.125″
- A2 envelopes: 4.375″ x 5.75″
- A7 envelopes: 5.75″ x 7.5″
Standard letter-sized envelopes are designed to hold a single sheet of paper folded in thirds. This results in a maximum capacity of around 5-6 pages for a standard business envelope.
The weight of a typical envelope containing just a few sheets of 20 lb printer paper will be 1 oz or less. This fits within the guidelines for a single 1 oz First-Class Mail Forever stamp.
When is a Second Stamp Needed?
Some situations when a standard letter-sized envelope would require additional postage include:
- The envelope weighs more than 1 oz – Each additional ounce over 1 oz requires an extra Forever stamp.
- Extra services have been added – Options like certified mail, return receipt, or additional insurance coverage require additional fees.
- The destination is international – Letters sent internationally have higher rates.
Here are some examples of when extra postage stamps would be required:
| Envelope Contents | Weight | # of Stamps Needed |
|---|---|---|
| 5 sheets of paper + brochure | 1.2 oz | 2 stamps |
| Legal documents | 9 oz | 10 stamps |
| Travel photos + souvenirs | 3.8 oz | 4 stamps |
As shown above, envelopes containing more than 1 oz of content will need each additional ounce to be covered by another Forever stamp. So a 9 oz package would need 10 Forever stamps – 1 for the first ounce and 9 more stamps for the additional weight.
Non-Standard Envelopes
If mailing something in a non-standard, larger envelope there are some other considerations for required postage:
- Oversized envelopes – Anything over 6.125″ high or 11.5″ long requires additional postage.
- Thick envelopes – If thickness is over 0.25″, extra fees may apply.
- Square envelopes – Square shaped may incur surcharges.
The Postal Service provides tools to calculate the postage needed for irregular shaped envelopes or packages. But in general, anything outside the standard letter-sized envelope dimensions may require extra postage.
Additional Postage Services
Adding extra services like certified mail or return receipt will also require additional postage to the basic weight-based rate:
- Certified Mail – Provides sender with proof of mailing and delivery. Costs $3.50 in additional fees.
- Return receipt – Provides proof the mailpiece was delivered. Costs $2.85 electronically or $2.10 by physical copy.
- Insurance – Provides coverage for lost or damaged items. Costs vary based on value insured.
If the letter is valued over $50, registered mail service starts at $12.50 and provides maximum security, tracking, insurance coverage, and proof of delivery. Other premium services like Priority Mail Express also have higher rates than standard First-Class postage.
International Mail
Sending mail to recipients in other countries will have higher postage rates. The cost varies greatly depending on the destination. Some examples for 1 oz letters include:
- Canada – $1.30
- Mexico – $1.30
- UK – $1.30
- Australia – $1.30
- China – $1.30
So a standard letter to international destinations will need extra stamps to cover this higher rate. The USPS website has tables listing the international rates for all countries and mail classes.
Large Envelopes and Packages Internationally
For large envelopes and packages sent internationally, the USPS has changed to a new price structure as of January 22, 2023. The pricing is now based on the weight and destination zone rather than just the weight. Some key points:
- Three international zones for pricing – 1 (Canada), 2 (Mexico), and 3-18 for all other countries.
- Pricing starts at around $26 for a 1 lb package to Zone 1 countries.
- Each additional pound is another $14-$18 depending on the zone.
- Size limits also apply for international packages.
With the new rates, a 10 lb package to Europe could cost $150-$180 to mail internationally. So it’s important to check the revised USPS postage calculators before mailing heavyweight envelopes or packages overseas.
Using Postage Stamps
Once you’ve determined the required postage for your envelope or package, the stamps need to be applied correctly for the USPS machines to accept it:
- Forever Stamps – Always accepted for 1 oz letters, no need for additional 1¢ stamps.
- Position carefully – Place stamps squarely in upper right corner.
- Use proper postage – Match rate stamps to the service required.
- Add markings – Any extra services or other rate markings as needed.
Some final tips on using the right postage:
- For standard letters under 1 oz, one Forever stamp is enough.
- Use a scale to check envelope weight if unsure.
- Calculate any extra fees for added services or international mail.
- Place stamps correctly or mail may be rejected.
Conclusion
In summary, a standard letter-sized envelope weighing 1 oz or less requires just a single Forever stamp for first-class mail within the US. Situations requiring extra postage include:
- Heavier envelopes over 1 oz – each additional ounce needs another Forever stamp
- Non-standard sized or shaped envelopes may incur surcharges
- Added services like certified mail or return receipt require additional fees
- International mail has higher rates that vary by country
Always weigh envelopes and double check with USPS rate calculators if uncertain. Use scales, accurate weighed samples, or take envelopes into the Post Office for verification. Applying the proper amount of postage ensures timely and reliable delivery of all letters and packages.
