Comparison

Plumbing Formulator vs Navisizer

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

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.

Highlights
  • 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
Features
Read full description

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.

About

Navisizer

This app helps size domestic hot water heating systems for residential and commercial use. It calculates operating costs, savings, and generates comprehensive job specifications for Navien NPE Series tankless water heaters.

Highlights
  • Residential system sizing
  • Operating cost and savings calculation
  • Commercial application sizing (ASHRAE Hunter Curve)
  • Tankless and tankless with storage solutions
  • Comprehensive job specification output
  • Save, print, or email system specs
Features
Read full description

NaviSizer is designed to assist with sizing of domestic hot water heating systems with Navien NPE Series tankless water heaters. For residential applications, NaviSizer offers system sizing, calculation of operating cost and savings, and provides a comprehensive output to be used as a job spec. For commercial applications, NaviSizer uses ASHREA Hunter Curve calculations to size a broad range of applications. Both tankless and tankless with storage solutions are offered along with a comprehensive system spec that can be saved, printed, or emailed.

Screenshots

Plumbing Formulator4 screens
Navisizer1 screens

Verdict

The call

The clearest difference is rating: Plumbing Formulator at 4.6 against Navisizer's 2.4. Navisizer's advantage is in-app purchases (none vs 4) and ratings volume (26 vs 7). On price, review sentiment, update cadence and ads 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Plumbing Formulator sells 4 one-off in-app purchases. Navisizer asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Plumbing Formulator holds the better App Store score, 4.6 against 2.4. Both are backed by a comparable volume of ratings — 7 and 26 respectively. Written reviews complicate that: 9% of Plumbing Formulator's written reviews are positive against 13% of Navisizer's, so the app with the better star average is not the one people write more warmly about.

UpkeepUpdate frequency

Plumbing Formulator ships an update every 2 months, Navisizer every 4 months. The most recent releases landed on August 23, 2026 and June 1, 2026 respectively.

Scorecard3 real differences · 7 level
Plumbing Formulator versus Navisizer: the parameters behind the verdict, then further details
ParameterPlumbing FormulatorNavisizer
PriceFreeFree
Rating4.6 (7 ratings) — better2.4 (26 ratings)
Positive reviews9.1% of reviews12.5% of reviews — better
Number of ratings726 — better
Update frequencyEvery 2 months — betterEvery 4 months
AdsNoNo
In-app purchasesYesNo — better
MonetizationFreeFree
DevicesiPhone, iPadiPhone, iPad
Requires iOS18.617.2 — better
Further details — not scored
Size123 MB21 MB
Age rating4+4+
DeveloperHistorycentral.comNavien, Inc.

Customer experience

Plumbing Formulator

All ratings7 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews11 reviews
Positive9.1%
Neutral0.0%
Negative90.9%

Navisizer

All ratings26 ratings
Positive34.6%
Neutral0.0%
Negative65.4%
Written reviews16 reviews
Positive12.5%
Neutral0.0%
Negative87.5%

In-app purchases

4 purchases

Plumbing Formulator

One-time4
  • Pro Version$1.99
  • Pro Purchase$3.99
  • Starter$5.99
Show 1 more
  • Growth$9.99
None

Navisizer

No in-app purchases

Questions

Is Plumbing Formulator free?
Plumbing Formulator is free to download, with in-app purchases available.
Is Navisizer free?
Navisizer is free to download, with no in-app purchases.
Which has better reviews, Plumbing Formulator or Navisizer?
Plumbing Formulator is rated higher. Plumbing Formulator averages 4.6 out of 5 from 7 ratings, while Navisizer averages 2.4 from 26 ratings.
Do Plumbing Formulator or Navisizer have ads?
Neither Plumbing Formulator nor Navisizer shows ads.
Which is updated more often, Plumbing Formulator or Navisizer?
Plumbing Formulator ships an update every 2 months, and Navisizer every 4 months. Most recently, Plumbing Formulator was updated on August 23, 2026 and Navisizer on June 1, 2026.

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