Maritime Calculators & Navigation Tools
Free nautical calculators, sailing navigation reference, and maritime measurement tools. Built for sailors, mariners, and anyone who works on the water.
Explore CalculatorsMost Used Maritime Calculators
Hull Speed Calculator
Calculate the theoretical maximum speed of a displacement hull based on waterline length.
Rhumb Line Distance Calculator
Compute constant bearing navigation distance between two coordinates.
Initial Bearing Calculator
Determine the forward azimuth between two geographic positions.
Nautical Distance Calculator
Measure sea distance between two points using spherical Earth models.
Most Used Maritime Calculators
- Nautical Mile ConverterConvert between nautical miles, statute miles, kilometers, and meters. Essential for chart work and passage planning.
- Knots to km/h ConverterConvert speed in knots to kilometers per hour. One knot equals 1.852 km/h.
- Hull Speed CalculatorEstimate theoretical hull speed from waterline length using the classic 1.34 × √LWL rule for displacement hulls.
- Initial Bearing CalculatorCompute the initial true bearing from one lat/lon waypoint to another (great-circle start heading).
- Great Circle Distance CalculatorCompute the shortest distance between two locations on Earth using latitude and longitude. Results in nautical miles and kilometers.
- Boat Fuel Consumption CalculatorEstimate fuel needed for a passage from consumption rate and travel time or distance and speed.
- VMG CalculatorVelocity made good toward a mark: boat speed × cos(angle off bow to the mark).
Browse all maritime calculators — the full index appears above the site footer on every page.
Recently Updated Calculators
- Updated hull speed calculation tool with refined formula handling
- Improved rhumb line navigation distance computation
- Updated bearing calculation accuracy for navigation
- Refined great-circle distance computation
- Enhanced deviation measurement tool for route tracking
- Improved speed over ground calculations with vector inputs
- Updated radar horizon estimation formulas
- Improved visibility range calculations
Navigation Calculation Categories
These calculation groups reflect core maritime navigation domains, including distance computation, bearing calculation, vessel performance, and environmental analysis.