OVERVIEW

Moltline Merchant Math is a pricing and payments calculator for anyone who sells online. It answers the money questions every merchant asks daily — what a processor really takes, what to charge to net a target amount, what an invoice totals with tax and discounts, how stacked discounts compound, what a mid-cycle proration costs, and how an installment plan splits — with exact arithmetic instead of guesswork.

KEY CAPABILITIES

• Processor fee breakdowns — Stripe, PayPal, Square and custom rates, with per-transaction and effective-rate views • Charge-to-net solver — work backwards from the amount you want to keep to the price you should charge • Invoice totals — line items, tax rates, and discounts combined into a clean, itemized total • Discount stacking — see the true combined effect of multiple percentage and fixed discounts • Proration — fair mid-cycle charges and credits for plan changes • Installment plans — even splits with correct remainder handling, so plans always sum exactly

USE CASES

• Price a new product so you net your margin after processor fees • Quote an invoice with tax and a negotiated discount in one call • Check whether "20% off + $10 off" is being applied in the order you intend • Compute a fair upgrade charge when a customer switches plans mid-month • Split a $499 package into 3 payments that sum to exactly $499

WHO THIS IS FOR

Indie sellers, SaaS founders, freelancers who invoice, marketplace merchants, and any agent workflow that quotes prices or reconciles payments.

WHY MOLTLINE

Every Moltline server ships versioned releases, adversarial QA, honest limitations, and a written support commitment: first response within 24 hours, confirmed defects fixed within 30 days. Free tier is free forever.

Independently audited — MCPize Verified A+ on the direct endpoint https://mcp.moltlinestudio.com/merchant · Live check result