Propeller Calc vs FUEL DENSITY
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Propeller Calc
This utility calculates propeller performance metrics like pitch, gear ratio, RPM, slip, and speed. Input any four values, and the app computes the fifth, helping users understand the relationship between propeller design and boat performance.
- Calculate pitch, gear ratio, RPM, slip, and speed
- Enter any four variables to find the fifth
- Understand propeller slip and its impact
- Supports iPhone and iPad
- Free to use
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This calculator can determine pitch, gear ratio, RPM, propeller slip and speed parameters. Enter any four variables, and it will calculate the fifth. Use the toggle switch to choose which field to calculate. Pitch is the theoretical forward movement for one complete turn of the propeller. Every inch of the boat in contact with the water induces drag. Therefore, the distance travelled differs since the propeller is "slipping" behind the theoretical distance it should travel with each rotation. The difference between theory and reality is called slip. Depending on your application, slip typically ranges between 5% and 20%. A lower number is only sometimes what you are after. Slip of a prop changes with operating conditions and is not a direct measure of efficiency. Please consult professionals for guidance. Happy powerboating
FUEL DENSITY
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CORRECTION OF FUEL DENSITY
Screenshots
Verdict
The clearest difference is price: Propeller Calc at Free against FUEL DENSITY's $2.99. FUEL DENSITY's advantage is update cadence (every 5 days vs every 21 months) and iOS requirement (15.2 vs 17.0). On 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
Propeller Calc is free to download; FUEL DENSITY costs $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Propeller Calc ships an update every 21 months, FUEL DENSITY every 5 days. The most recent releases landed on September 26, 2026 and October 8, 2026 respectively.
| Parameter | Propeller Calc | FUEL DENSITY |
|---|---|---|
| Price | Free — better | $2.99 |
| Rating | 3.0 (1 ratings) — better | — |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 1 — better | — |
| Update frequency | Every 21 months | Every 5 days — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | — |
| Devices | iPhone, iPad | iPhone, iPod |
| Requires iOS | 17.0 | 15.2 — better |
| Further details — not scored | ||
| Size | 3 MB | 2 MB |
| Age rating | 4+ | 17+ |
| Developer | Frode Rørvik | Oleksii Nezhalskyi |
In-app purchases
Propeller Calc
No in-app purchases
FUEL DENSITY
No in-app purchases
Questions
Is Propeller Calc free?
Is FUEL DENSITY free?
Do Propeller Calc or FUEL DENSITY have ads?
Which is updated more often, Propeller Calc or FUEL DENSITY?
Other comparisons
