Shopify's plan is a fixed monthly price. Basic is $39 billed monthly or $29 a month billed yearly, Grow is $105 or $79, Advanced is $399 or $299, and Plus starts at $2,300. A fixed cost only means something per order, so the calculator divides the plan by your monthly orders: a store with 20 orders a month pays far more per order for the same plan than one with 500.
Shopify Payments charges a card rate on each online order: 2.9% on Basic, 2.7% on Grow, 2.5% on Advanced, and 2.25% on Plus, each plus 30 cents. Premium cards such as rewards and corporate cards cost more, from 3.5% on Basic down to 2.95% on Plus, and international cards add 1%. The calculator applies the card rate to the full amount the customer pays, including shipping and tax.
If you take payments through a provider other than Shopify Payments, Shopify adds its own transaction fee on top of that provider's charges: 2% on Basic, 1% on Grow, 0.6% on Advanced, and 0.2% on Plus. Your provider's processing fee varies and is not included in the total.
Apps, themes, a domain, and shipping labels are real costs too, but they vary too much to model. Add a per-order share of them to packaging cost if you want them in the profit figure.
Cost per order = plan price / orders per month + card % x (item + shipping + tax) + $0.30 [or third-party fee % x total]