Navisizer vs Ductulator
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
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.
- 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
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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.
Ductulator
Instantly calculate HVAC duct sizes based on airflow, friction rate, or velocity. This tool provides accurate duct dimensions in seconds without needing charts, supporting various duct types and units.
- Instant duct sizing
- Friction rate or velocity calculation
- Multiple valid duct dimensions
- IP and SI units support
- Detailed sizing mode
- Rectangular, circular, and flexible ducts
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Size HVAC ducts instantly using airflow, friction or velocity. Get accurate duct dimensions in seconds — no charts required. • Get a range of suitable duct sizes based on friction rate or velocity. • Get multiple valid duct dimensions instantly. • Tap on Friction Rate or Velocity to toggle between calculation methods. • IP and SI units. • Detailed sizing mode to adjust the duct dimensions and air flow rates. • Supports rectangular, circular and flexible ducts. • Automatic friction and velocity updates. Calculations are based on standard air 0.075 lb/ft3 (1.2 kg/m3) in clean galvanized steel or non-metallic flexible ducts. Any feedback is welcome, and will be the basis for future updates.
Screenshots
Verdict
The clearest difference is price: Navisizer at Free against Ductulator's $3.99. Ductulator's advantage is rating (4.7 vs 2.4) and review sentiment (50% vs 13%). On update cadence, ads, in-app purchases and monetization model 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
Navisizer is free to download; Ductulator costs $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Ductulator holds the better App Store score, 4.7 against 2.4. That said, the two scores are not equally well evidenced: Ductulator has 317 ratings behind it against 26, so its average is the more settled of the two. Written reviews point the same way: 13% of Navisizer's written reviews are positive against 50% of Ductulator's.
Navisizer ships an update every 4 months, Ductulator every 2 months. The most recent releases landed on June 1, 2026 and September 22, 2026 respectively.
| Parameter | Navisizer | Ductulator |
|---|---|---|
| Price | Free — better | $3.99 |
| Rating | 2.4 (26 ratings) | 4.7 (317 ratings) — better |
| Positive reviews | 12.5% of reviews | 50.0% of reviews — better |
| Number of ratings | 26 | 317 — better |
| Update frequency | Every 4 months | Every 2 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Best chart rank | — | #27 — better |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 17.2 — better | 18.6 |
| Further details — not scored | ||
| Size | 21 MB | 1 MB |
| Age rating | 4+ | 4+ |
| Developer | Navien, Inc. | Wassim Murr |
Customer experience
Navisizer
Ductulator
In-app purchases
Navisizer
No in-app purchases
Ductulator
No in-app purchases
Questions
Is Navisizer free?
Is Ductulator free?
Which has better reviews, Navisizer or Ductulator?
Do Navisizer or Ductulator have ads?
Which is updated more often, Navisizer or Ductulator?
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