# Flowbox: Plumber Toolkit — Plumbing Job Site Calculators

> Plumbing Job Site Calculators (iPhone/iPad app by GABRIELE CHESI.)

- Source: https://appshunter.io/ios/app/flowbox-plumber-toolkit/id6801521180 (this page in markdown: same URL + `.md`)
- Developer: [GABRIELE CHESI](https://appshunter.io/developer/6793043905)
- Category: Utilities
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 13.0 · 25 MB
- Languages: American English
- Released: 2026-08-31
- Data updated: 2026-09-05
- User reviews in markdown: https://appshunter.io/ios/app/flowbox-plumber-toolkit/id6801521180/reviews.md

## What is Flowbox?

Flowbox is a professional toolkit for plumbers — job-site calculators covering drainage, venting, water supply, gas piping, and pipe fitting, all on-device with no account required.

PIPE FUNDAMENTALS
• Pipe Slope — solve rise, run, or grade against IPC minimums
• Pipe Offset — travel and run for 45°, 22.5°, 60°, and other fittings
• Flow Rate & Pressure Drop — Hazen-Williams friction loss for water pipe runs
• Pipe Volume — water capacity of a pipe segment from ID and length

DRAINAGE & VENTING
• Drain Sizing — minimum drain pipe size from fixture unit load (DFU)
• Vent Sizing — vent pipe diameter from DFU load and developed length
• Sump/Ejector Pump Sizing — total dynamic head and horsepower from inflow and lift
• Grease Trap Sizing — interceptor capacity from kitchen fixture flow rate

SUPPLY & GAS
• Water Supply Sizing — distribution pipe size from fixture unit demand (WSFU)
• Gas Pipe Sizing — pipe size from BTU load and length, longest-length method
• Water Heater Sizing — first hour rating or tankless GPM from peak demand
• Water Hammer Arrestor — PDI-WH201 size from branch fixture units
• Thermal Expansion — pipe growth and expansion loop size by material

WHY FLOWBOX
Pro unlock is a one-time purchase — no subscription, ever. No ads. No server required to use any calculator. Free tools (Pipe Slope, Drain Sizing, Pipe Volume) cover everyday use; Pro unlocks the full set. An optional Pro feature lets you sync your saved calculations and projects across your own devices via your own iCloud or Google Drive — off by default, and your data never touches our servers because we don't have any.

Flowbox is a reference tool for estimating — always verify pipe slope, drain and vent sizing, water supply sizing, and gas pipe sizing against your local plumbing code (IPC or UPC as adopted locally) and a licensed professional before cutting, sizing, or installing. Gas piping in particular carries real safety consequences if undersized or misrouted.

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Flowbox Pro Unlock | $8.99 | one-time |



## Version history (last 1 release)

### 1.0 — 2026-09-01

No release notes.

## More apps by GABRIELE CHESI

- [Voltbox: Electrician Toolkit](https://appshunter.io/ios/app/voltbox-electrician-toolkit/id6793043903)
- [Brickbox: Mason Toolkit](https://appshunter.io/ios/app/brickbox-mason-toolkit/id6798297551)
- [Voltbox: PV Installer Toolkit](https://appshunter.io/ios/app/voltbox-pv-installer-toolkit/id6798591811)
- [Timberbox: Carpenter Toolkit](https://appshunter.io/ios/app/timberbox-carpenter-toolkit/id6799141230)
- [Vectorbox: Pilot Toolkit](https://appshunter.io/ios/app/vectorbox-pilot-toolkit/id6800001910)

All apps by GABRIELE CHESI: https://appshunter.io/developer/6793043905

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-09-05.*