Plumbing Formulator vs iManifold
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Plumbing Formulator
This professional calculator app provides over 200 formulas, calculators, and reference materials for plumbers, HVAC technicians, and mechanical contractors. It covers a wide range of calculations for water flow, piping, drainage, water heaters, pumps, and more, all in one pocket-sized tool.
- Over 200 formulas and calculators
- Water flow and supply calculations
- Pipe and piping calculations
- Drainage and venting calculations
- Water heater and pump calculations
- Reference charts and code books
- Pipe cut list optimizer
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PLUMBING FORMULATOR is the ultimate professional calculator for plumbers, HVAC techs, and mechanical contractors. Over 200 formulas, reference charts, code books, and pro tools in your pocket. CALCULATORS AND FORMULAS Water Flow and Supply: pipe velocity, flow rate, GPM, fixture unit demand, and supply sizing. Pipes and Piping: area, volume, and weight for copper, steel, cast iron, and plastic. Hazen-Williams friction loss, pressure ratings, and 45 degree offsets. Drainage and Venting: drain sizing, slope and fall, vent sizing, fixture units, and wet vents. Water Heaters: BTU requirements, recovery rates, tank sizing, first hour ratings, and hot water demand. Pumps and Pressure: water and brake horsepower, efficiency, head pressure, velocity head, and PSI to feet of head. Storm Drainage: roof drains, rainfall intensity, gutter and leader sizing, and retention. Gas Piping: size natural gas and propane lines, BTU loads, pressure drop, and appliance demand. Medical Gas: size oxygen, nitrogen, nitrous oxide, and medical air. Vacuum demand and manifolds per NFPA 99. Swimming Pools: volume, fill time, pump sizing, turnover, evaporation loss, and main drains. Septic and Sewage: septic tanks, leach fields, and sewage pump capacity. Thermal Expansion: expansion tank sizing, system pressure, and pipe length changes. REFERENCE MATERIALS Charts and Tables: dozens of reference charts including pipe sizing, fixture units, and materials in PDF. Massachusetts Plumbing Code: complete 248 CMR reference with all chapters. Plumbing Design Guide: a 24 chapter design and installation guide. Technical Drawings: professional diagrams and installation details. TOOLS AND FEATURES Pipe Cut List Optimizer: enter lengths and stock sizes for an optimized cutting plan that cuts waste. Unit Conversions: length, area, volume, flow, pressure, temperature, weight, and power. Geometry Calculators: area and volume for circles, rectangles, triangles, cylinders, spheres, cones, and more. BUSINESS MANAGEMENT More than a calculator. Tap Business to run your service company from the same app. Customers: contacts, service addresses, job history, and outstanding balances. More than a calculator. Tap Business to run your service company from the same app. Customers: contacts, service addresses, job history, and outstanding balances. Quotes and Estimates: build quotes on site and turn an approved quote into an invoice with one tap. Invoicing: branded invoices with your logo, parts and labor, taxes, and terms. Send by email, print, or PDF. Payments: cash, check, card, ACH, or credit. Apply one payment across invoices and manage credit automatically. Scheduling: book service calls, track jobs, and set up recurring contracts that auto-generate invoices. Business Reports: balances, receivable aging, revenue, and payment history. Export as CSV or PDF. Business features are a separate one-time upgrade, discounted for existing Bill-Craft and ServiceBoss customers. PLUMBING PRO FEATURES Upgrade to Plumbing Pro to save calculations with full detail, export results, keep unlimited history, and remove ads. One time purchase with lifetime access. A modern dark interface built for the job site, with breakdowns showing the steps and formulas behind every result. Perfect for plumbers, apprentices, HVAC techs, mechanical engineers, and building inspectors. Download Plumbing Formulator today and put professional plumbing calculations at your fingertips.
iManifold
This app calculates HVAC/R system performance and aids in troubleshooting. It offers a wide selection of refrigerants and equipment profiling for various common systems.
- Calculates HVAC/R system performance
- Troubleshoots system problems
- User input and live system data
- Over 40 selectable refrigerants
- Equipment profiling options
- Customizable for common HVAC/R systems
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The iManifold App Calculates HVAC/R system performance and troubleshoots system problems through user inputs and dynamic, live system data. With over 40 selectable refrigerants and equipment profiling options, the iManifold app can be custom tailored for many common HVAC/R systems in the field.
Screenshots
Verdict
The clearest difference is rating: Plumbing Formulator at 4.6 against iManifold's 3.1. Plumbing Formulator also leads on monetization model (free vs free with in-app purchases). iManifold's advantage is review sentiment (50% vs 9%) and update cadence (every 3 weeks vs every 2 months). On price, ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Plumbing Formulator sells 4 one-off in-app purchases and iManifold sells 10 one-off in-app purchases. Whichever you choose, the download price is not the number that matters.
Plumbing Formulator holds the better App Store score, 4.6 against 3.1. That said, the two scores are not equally well evidenced: iManifold has 38 ratings behind it against 7, so its average is the more settled of the two. Written reviews complicate that: 9% of Plumbing Formulator's written reviews are positive against 50% of iManifold's, so the app with the better star average is not the one people write more warmly about.
Plumbing Formulator ships an update every 2 months, iManifold every 3 weeks. Both last shipped on October 23, 2026.
| Parameter | Plumbing Formulator | iManifold |
|---|---|---|
| Price | Free | Free |
| Rating | 4.6 (7 ratings) — better | 3.1 (38 ratings) |
| Positive reviews | 9.1% of reviews | 50.0% of reviews — better |
| Number of ratings | 7 | 38 — better |
| Update frequency | Every 2 months | Every 3 weeks — better |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Free — better | Free with in-app purchases |
| Devices | iPhone, iPad | iPhone, iPad, iPod — better |
| Requires iOS | 18.6 | 12.0 — better |
| Further details — not scored | ||
| Size | 123 MB | 29 MB |
| Age rating | 4+ | 4+ |
| Developer | Historycentral.com | North Park Innovations Group, Inc. |
Customer experience
Plumbing Formulator
iManifold
In-app purchases
Plumbing Formulator
- Pro Version$1.99
- Pro Purchase$3.99
- Starter$5.99
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- Growth$9.99
iManifold
- Charge & Airflow Report$0.99
- Mechanical Inspection$0.99
- Equipment Replacement Report$0.99
Show 7 moreShow fewer
- CSV Export$0.99
- Annualized Savings Report$0.99
- Gas Furnace Report$0.99
- iManifold Report Pro - 1 Circuit$1.99
- iManifold Report Pro - 2 Circuit$2.99
- iManifold Report Pro - 3 Circuit$3.99
- iManifold Report Pro - 4 Circuit$4.99
Questions
Is Plumbing Formulator free?
Is iManifold free?
Which has better reviews, Plumbing Formulator or iManifold?
Do Plumbing Formulator or iManifold have ads?
Which is updated more often, Plumbing Formulator or iManifold?
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