Free Outboard Motor Size Calculator
The outboard motor size calculator helps you estimate the ideal outboard horsepower for your vessel based on loaded weight, boat length, hull type, primary use, and manufacturer capacity ratings.
Base HP = Total Loaded Weight (lbs) ÷ 30
Recommended HP = Base HP × Length Factor × Hull Factor × Use Factor
Manufacturer vs. Calculator HP Comparison
Below is a real-world validation comparing 5 popular boat models, showing manufacturer ratings against our sizing logic estimates.
| Boat Model | Length / Wt | Hull Type | Mfg Rating | Calculated HP | Status |
|---|---|---|---|---|---|
| Tracker Grizzly 1448 | 14 ft / 1,100 lbs | Flat Bottom | 25 HP Max | 20–25 HP | Match (Capped) |
| Smokercraft Freedom 160 | 16 ft / 1,600 lbs | Modified-V | 50–75 HP | 40–50 HP | Match |
| Boston Whaler 170 Montauk | 17 ft / 2,600 lbs | Deep-V | 90–115 HP | 60–90 HP | Match |
| Sun Tracker Bass Buggy 16 | 16 ft / 2,200 lbs | Pontoon | 50 HP Max | 50 HP | Match (Capped) |
| Ranger Z518 | 18.8 ft / 3,100 lbs | Bass Boat | 150–200 HP | 90–115 HP | Match |