Tools you might need next
Calculate sail area from luff, leech, and foot measurements for different sail types. Estimate mainsail and headsail area for sailing performance.
Calculate boat displacement and hull speed from waterline length and beam. Estimate vessel weight and theoretical speed for sail and power boats.
Calculate anchor size and rode length from boat length, weight, and conditions. Select ground tackle for safe anchoring in varied wind and bottom.
Consumption in gallons or liters per hour at a given RPM and load. Manufacturer specs or measured burn at cruise throttle provide the base rate.
Burn rate (GPH) at cruise RPM from engine spec or flow meterRange equals usable fuel divided by consumption, multiplied by speed. Apply 20–33% reserve — never plan to empty the tank.
Range (nm) = (usable fuel / GPH) × speed (knots)Fuel consumption rises roughly with speed cubed on displacement hulls. Reducing speed 10% can reduce fuel burn 25–30% on many powerboats.
Fuel ∝ speed³ (displacement hull approximation)Updated: July 2026
Cruise at 7 knots burning 3 GPH. Usable 80 gal (20% reserve): range = (80/3) × 7 ≈ 187 nm. Plan refuel stops every 150 nm for margin.
At 12 knots: 8 GPH, 60 gal usable → 90 nm range. At 9 knots: 4 GPH → 135 nm range. Slowing 25% nearly doubles range.
30 gal diesel, 1.2 GPH at 5.5 knots motoring: (24 gal usable / 1.2) × 5.5 = 110 nm engine range for calm-no-wind contingency.
Fuel gauges are inaccurate, especially near empty. Plan arrival with 25–33% reserve minimum. Running out of fuel at sea is a leading cause of towing calls.
Wide-open throttle consumption is 2–3× cruise burn. Range calculations must use the RPM and throttle setting you actually cruise at.
Fuel range planning prevents running dry on long passages. This calculator estimates nautical range from tank capacity, fuel burn rate at cruising RPM, and speed, with reserve allowance for safety.