Pricing

Calculation credits
$19

40 calculations. Sales tax, where it applies, is added at checkout.

  • One credit = one completed calculation (web or API). Water supply and drainage are separate calculations: 1 credit each, so a job with both uses 2
  • Inputs that can't be calculated (out of range, missing a value) don't use a credit
  • Reopening, printing or downloading a past result is free
  • Credits don't expire
  • Full refund within 30 days if you're not satisfied (one per account per year) — see the refund policy

Before you buy: full refund within 30 days, one per account per 12 months. After a refund, purchases pause for 12 months (or make a non-refundable re-entry purchase). A second full refund within 12 months, on any account or with the same card, permanently closes the account. Refund Policy

Sign in to buy

Checkout is run by Stripe. The order is sold through Link (Stripe's checkout service), which acts as merchant of record: it collects sales tax and sends the receipt, and your card statement shows LINK.COM*. We never see your card number.

What a calculation includes

  • Fixture units, demand in gpm, minimum Type L or K copper size
  • Velocity and Hazen-Williams friction loss
  • Optional pressure budget (street, elevation, fixture minimum, meter loss)
  • No-water fixture list and pressure flags
  • Version, time, sources and disclaimer stamped on the result