USPS Priority Mail
3 lbs DIM
Actual weight: 2.5 lbs
Billable weight: 2.5 lbs
Estimated cost per box: $2.13
Packaging is efficient
Optimized cost per box: $2.13
Shipping
Subscription Box Shipping Calculator
Calculate the real shipping cost for your box and see how DIM weight affects annual spend.
Box dimensions
Carrier selection
Enter your negotiated or retail rate per pound. 3PLs typically get 15-25% below retail rates.
DIM weight results
UPS Ground
4 lbs DIM
Actual weight: 2.5 lbs
Billable weight: 4 lbs
Estimated cost per box: $3.80
Paying for air
Optimized cost per box: $2.38
FedEx Ground
4 lbs DIM
Actual weight: 2.5 lbs
Billable weight: 4 lbs
Estimated cost per box: $3.80
Paying for air
Optimized cost per box: $2.38
Current box
12 × 10 × 4 in
Monthly shipping at 200 subscribers
Cheapest selected carrier: USPS Priority Mail at $2.13 / box
Optimized box
10 × 8 × 2 in
2 inches smaller on each side
Cheapest selected carrier: USPS Priority Mail at $2.13 / box
Savings
$0.00 / month
$0.00 / year
Based on your cheapest selected carrier
DIM weight problem
You are paying for air. Your box's DIM weight is 4 lbs but it only weighs 2.5 lbs.
At 200 subscribers, this costs you an extra $0.00/month compared to a right-sized box.
Reducing your box by 2 inches on each side would bring DIM weight to 10 × 8 × 2 inches and lower the billable weight across the selected carriers.
Optimized box dimensions:
New DIM weight: 1 lbs
New cost per box: $2.13
Monthly savings at 200 subscribers: $0.00
Annual savings: $0.00
Carrier comparison table
| Carrier | DIM Weight | Billable Weight | Cost Per Box | Monthly Cost | Annual Cost |
|---|---|---|---|---|---|
| USPS Priority Mail | 3 lbs | 2.5 lbs | $2.13 | $425.00 | $5,100.00 |
| UPS Ground | 4 lbs | 4 lbs | $3.80 | $760.00 | $9,120.00 |
| FedEx Ground | 4 lbs | 4 lbs | $3.80 | $760.00 | $9,120.00 |
Annual impact
| Subscribers | Cheapest Carrier | Monthly Shipping Cost | Annual Shipping Cost |
|---|---|---|---|
| 100 | USPS Priority Mail | $212.50 | $2,550.00 |
| 500 | USPS Priority Mail | $1,062.50 | $12,750.00 |
| 1000 | USPS Priority Mail | $2,125.00 | $25,500.00 |
Box size optimizer
Your products fit in a 12 × 10 × 4 box with 1 inch padding on each side.
This gives a DIM weight of 4 lbs.
Why DIM weight surprises subscription box owners
Carriers charge based on whichever is greater - actual weight or dimensional weight. A large lightweight box can cost far more to ship than a heavier but smaller one. The DIM divisor for UPS and FedEx is 139, meaning a 12 × 10 × 8 inch box has a DIM weight of 6.9 lbs regardless of what is inside.
How to reduce shipping costs
Use the smallest box that safely fits your products. Consider poly mailers for soft goods - they have no DIM weight penalty. 3PLs get volume-negotiated carrier rates typically 15-25% below retail. Right-sizing your packaging is often the fastest way to improve margin without raising your price.
Carrier comparison quick reference
| Carrier | DIM Divisor | Good for |
|---|---|---|
| USPS Priority | 166 | Light packages under 1 lb, short distances |
| UPS Ground | 139 | Medium weight, longer distances |
| FedEx Ground | 139 | Similar to UPS, competitive in certain regions |
Next steps
Shipping cost is part of your COGS: