Five core areas. Each one covers specific decisions with specific numbers. Spreadsheets included where the math matters.
Carriers don't charge only by pounds. They calculate what's called dimensional weight, which is derived from the length, width, and height of your box divided by a carrier-specific divisor. When that calculated weight exceeds the actual scale weight, you pay the higher number.
This matters most for lightweight items in large boxes. A candle in an oversized box, a piece of clothing with generous packing material, a ceramic mug in a box with too much air. All of these trigger dimensional weight charges that can double or triple what you'd pay based on scale weight alone.
The formulas differ by carrier. This post walks through each one with examples at different box sizes.
Practical guidance on which box dimensions create the best weight-to-size ratio for common product categories.
Enter your box dimensions and product weight. The sheet calculates billable weight across four carriers automatically.
USPS flat rate boxes offer a fixed price regardless of weight, which sounds like a clear win. It isn't always. The flat rate price is fixed, but it's also zone-independent, which means short-distance shipments that would be cheap anyway end up overpriced. Long-distance shipments to Zone 8 are where flat rate tends to actually save money.
The other variable is product density. Heavy items in small boxes benefit from flat rate pricing because actual weight would be expensive. Light items in the same box often don't reach the flat rate breakeven point.
Rate tables showing flat rate versus zone-based pricing across common shipping zones and product weights.
USPS cubic pricing is available through third-party platforms. It can be cheaper than flat rate for specific size and weight combinations.
Small, medium, and large flat rate box analysis with the exact weight and zone combinations where each makes financial sense.
UPS and FedEx both have published retail rates and then a separate set of rates negotiated by accounts. The gap between the two can be significant. Small volume doesn't disqualify you from negotiating. It does limit what you can realistically ask for, and knowing that limit in advance makes the conversation more productive.
The leverage points at low volume include predictable shipping patterns, specific service commitments, and the possibility of growth. This post series covers how to prepare for that conversation and what to ask for.
Realistic expectations for small-volume negotiation. What's typical, what's exceptional, and what's not available at this volume.
The data you need to bring: average weight, average zone, service mix, and monthly volume. How to present it clearly.
Both platforms offer discounted USPS and UPS rates through their carrier agreements. Pirate Ship is free to use and passes through its negotiated rates. ShipStation charges a monthly fee but offers more integrations and automation features. Which makes sense depends on your volume and how much time you spend on manual label creation.
The default settings on both platforms don't always select the cheapest service for a given shipment. Configuration matters.
The settings that affect cost most, including cubic pricing enablement, insurance defaults, and address validation behavior.
Feature-by-feature breakdown of ShipStation plans relative to the monthly cost and what each tier unlocks.
Real rate examples across common shipment types showing where each platform is cheaper or more expensive.
A return costs more than the outbound shipping plus the return label. The time to process it is real labor. If the product needs repackaging, there's material cost. If it sits for any time before restocking, there's an opportunity cost. Building a complete returns cost model changes how you think about return policies and product pricing.
This is especially relevant for small makers where each return is handled personally, not by a fulfillment center. The hourly cost of your own time is easy to overlook when it doesn't appear on an invoice.
A framework for calculating the full cost of a return including shipping both ways, time, repackaging, and restocking.
The relationship between return window length, label type, and how often customers actually use the policy.
Enter your outbound rate, return rate, hourly rate for processing time, and repackaging cost. The sheet outputs cost per order.