Accurate gas pipe sizing is one of the highest‑risk, highest‑cost tasks on residential and light‑commercial jobs. Conventional tables and simple online tools force installers into conservative “longest run” sizing that is safe but often wasteful — or into risky shortcuts when real system geometry and fittings aren’t handled properly. Our calculator solves that by running both the Longest‑Run and Branch‑Length methods, accounting for fittings (equivalent length), gas type (natural gas vs propane), and the underlying flow physics so you get compliant, verifiable results — and a transparent Material Savings Report showing real dollars saved when optimizations are valid.
What this calculator does
- Computes pipe diameters using both the Longest‑Run and Branch‑Length methods required by NFPA 54 / IFGC.
- Uses the Spitzglass (low‑pressure) and Weymouth (high‑pressure) models behind the scenes to validate and extend code table lookups.
- Automatically applies specific gravity and heating‑value differences for natural gas and propane.
- Adds fittings as equivalent length per diameter/material so pressure‑drop inputs match reality.
- Visualizes the system as a node‑tree (SVG diagram) and produces a Material Savings Report that quantifies pipe downsizing and cost impact.
