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
- 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 (the great-circle route's starting bearing).
- 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.