A shipping box can have the right size and the right cushioning, but it still needs a secure seal. Weak tape, uncovered seams, or an improperly closed carton can lead to damaged products, delays, or packages opening during transit.
For most corrugated shipping boxes, seal the center opening and both outer edge seams to form an “H” on the top of the box. For heavier shipments, repeat the same pattern on the bottom.
This approach is commonly called the H-tape method. It helps keep all top flaps closed and reinforces the seams most likely to separate during handling.
What Is the H-Tape Method?
The H-tape method uses one strip of packing tape across the center seam where the box flaps meet, plus one strip along each outer edge seam. Viewed from above, the tape forms an H shape.
For a standard box:
- Fold all four box flaps closed.
- Apply one continuous strip of tape down the center seam.
- Add one strip of tape across each outer edge seam.
- For heavier shipments, repeat the same pattern on the bottom of the box.
FedEx recommends applying tape across flaps and seams on the top and bottom of corrugated boxes using the H-tape method. See FedEx packing guidance.
Choose Tape Made for Shipping
Use packaging tape designed to seal corrugated cartons. Clear or brown packing tape, reinforced tape, and suitable paper tape are common options for shipping boxes.
Avoid relying on masking tape, cellophane tape, string, or decorative tape for carton closure. USPS recommends taping the opening and reinforcing seams with shipping-appropriate tape. Review USPS package-preparation guidance.
Shop packing tape and shipping labels →
When Should You Use Extra Tape?
Not every shipment needs the same level of reinforcement. Add extra tape when the box is heavier, the contents are dense, or the package may receive more handling during transit.
Consider reinforcing the bottom and all seams when you ship:
- Heavy books, tools, dense retail products, or multi-item orders
- Glass, ceramics, electronics, or fragile products in a corrugated box
- Packages with a large amount of protective material
- Boxes that will be stored, moved, or handled several times before shipping
Before sealing, confirm that the contents are stable. Tape cannot compensate for an item that moves freely inside the carton. Use packing paper, bubble wrap, or other suitable protection to fill empty space first.
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Seal the Bottom Before You Pack
For a new corrugated shipping box, start with the bottom. Apply the H-tape pattern before placing the product inside. This gives the carton a more secure base and helps prevent the bottom flaps from opening under the weight of the contents.
After the item is packed and protected, close the top flaps and repeat the H-tape pattern. For very light shipments, one secure center strip may be adequate depending on the box and carrier requirements, but sealing all seams provides more dependable closure.
Use the Right Box Before You Tape
A properly sealed carton begins with the right box size. Choose a box with enough room for the product and cushioning, but not so much empty space that the contents can move around.
Read our guide to choosing the right shipping box size before standardizing packaging for your most common orders.
Shop corrugated shipping boxes →
How to Apply a Shipping Label
Apply the shipping label after the box is sealed. Place it flat on the largest top surface when possible, away from folds, corners, and tape seams.
Before handing the order to a carrier, check that:
- The barcode is flat and easy to scan.
- The recipient address and return address are correct.
- No old labels, barcodes, or shipping marks remain visible.
- The label does not wrap around a corner or box edge.
- The tape does not obscure important label information.
For recurring fulfillment, keep tape and labels at the same packing station so every order follows a consistent process.
A Simple Box-Sealing Workflow
- Select a corrugated box that fits the order.
- Seal the bottom with the H-tape method.
- Add the product and protective material.
- Gently shake the box; add void fill if the item moves.
- Seal the top with the H-tape method.
- Apply the shipping label flat on the top or largest side.
- Check the package weight and dimensions before purchasing postage.
For broader packing guidance, see our small business shipping checklist. If you are deciding between a box and a mailer, read Shipping Boxes vs. Poly Mailers.
Frequently Asked Questions
What is the H-tape method for shipping boxes?
The H-tape method seals the center opening and both outer edge seams of a corrugated box. The tape forms an H shape and helps keep every top flap secure.
Should I tape the bottom of a shipping box?
Yes. Seal the bottom before packing the product, especially when the shipment is heavy, dense, or contains multiple items. Use the same H-tape pattern on the bottom and top when more reinforcement is needed.
What tape should I use for corrugated boxes?
Use packing tape made for shipping, such as clear or brown carton-sealing tape, reinforced tape, or suitable paper tape. Choose tape and reinforcement based on the box weight, contents, and carrier requirements.
Can I use a poly mailer instead of a box?
Use a poly mailer for lightweight, flexible, durable products that do not need protection from crushing. Use a corrugated box when the product is fragile, rigid, heavy, or needs cushioning.
Keep Your Packing Station Ready
A reliable packing station needs the right boxes, protective materials, tape, labels, and a repeatable process. Warm Fortune Packaging supplies shipping boxes, tape, labels, packing paper, mailers, and other fulfillment essentials for businesses that ship regularly.
For case quantities, repeat orders, or volume pricing, request Business Pricing.