Formula
Per Order = (Base Fee + Weight × Rate + Packaging) × (1 + Surcharge %)
FAQ
Should returns be included here?
If you pay return shipping, add an estimate to the surcharge field — e.g. a 10% return rate with equal return cost ≈ +10%.
How do I price free shipping?
Use this result as the cost side, then check with the break-even calculator whether your margin can absorb it or whether it should be built into prices.