Every calculator, converter and guide on BoatCalculators, on one page. They are grouped as in the menu, Trip Planning, Boat Tools and Converters, with the guides at the end, and each comes with a line on what it works out. All of them are free, with no sign-up.
Trip Planning
Distance, time and fuel for a trip, the route pages, and the navigation and wind tools for the way there.
Distance, time and fuel
- Sea Distance Calculator
A marine distance calculator: nautical miles between ports on an interactive map.
- Boat Travel Time Calculator
Calculate how long your boat trip will take based on distance and vessel speed. Plan your voyage duration.
- Speed, Distance and Time Calculator
Find trip time, distance or average speed in knots, mph or km/h, with an arrival time.
- Boat Fuel Calculator
Calculate trip fuel consumption and cost based on distance, speed, and your boat’s fuel burn rate.
- Boat Routes
Distance, travel time, and fuel estimates for popular Florida and Bahamas boat routes.
- Port to Port Distance Calculator
Shipping distance and transit days between world seaports for cargo ships, via Suez, Panama or Kiel.
- Great Loop Calculator
Hours underway, cruising days, months and fuel for the roughly 6,000-mile Great Loop at your speed and pace.
- Float Plan Generator
Write a printable float plan with your boat, crew, route and return time to leave with someone ashore.
Navigation
- Horizon Distance Calculator
How far away the horizon is from your eye height, and how far you can see a lighthouse or another boat.
- Great Circle Distance Calculator
The shortest distance in nautical miles between two positions, the initial course and the rhumb line for comparison.
- Anchor Scope Calculator
How much anchor rode to let out for the depth, bow height, scope and tide, and how far the boat can swing.
- Tide Calculator
Height of the tide at any time between high and low water by the rule of twelfths, with the tidal range.
Wind and sailing
- True Wind Calculator
True wind speed and direction from the apparent wind and your boat speed, or the apparent wind from the true wind.
- VMG Calculator
Velocity made good upwind, downwind or toward a waypoint from boat speed and angle, with a second angle to compare.
Boat Tools
Speed and propellers, the engine, fuel and batteries, the boat’s weight and capacity, and buying a boat.
Speed and propellers
- Hull Speed Calculator
Calculate your boat’s theoretical hull speed based on waterline length.
- Boat Speed Calculator
Estimate a planing boat’s top speed from horsepower and loaded weight.
- Propeller Pitch Calculator
Find the speed for a propeller pitch and RPM, or the pitch you need for a target speed.
- Prop Slip Calculator
Compare your actual speed with the theoretical speed set by pitch, RPM and gear ratio.
- Sailboat Ratios Calculator
Sail area/displacement, displacement/length, comfort ratio and capsize screening formula of a sailboat.
Engine, fuel and batteries
- 2 Stroke Oil Mix Calculator
Calculate the perfect fuel-to-oil ratio for your 2-stroke outboard engine. Supports 25:1 to 100:1 ratios.
- Boat Fuel Tank Calculator
Gallons and liters in a box, wedge or round fuel tank from its inside dimensions, full or at a dipstick depth.
- Marine Battery Calculator
Daily amp-hours from your loads, the battery bank you need for lead-acid or lithium, and how long a battery lasts.
- Fuel and Water Weight Calculator
Weight of gasoline, diesel, fresh water or seawater by the gallon or liter.
Weight and capacity
- Boat Weight Calculator
Loaded boat weight from dry weight, engines, fuel, water, people and gear, plus the trailer for the towing total.
- Boat Displacement Calculator
Loaded displacement from the light displacement and what is aboard, the water displaced and how much deeper the boat floats.
- Tongue Weight Calculator
Boat trailer tongue weight as a percent of the loaded trailer weight, against the trailer maker’s range.
- Boat Capacity Calculator
Estimate persons, weight capacity and maximum horsepower with the U.S. Coast Guard formulas; the capacity plate comes first.
Buying a boat
- Boat Loan Calculator
Estimate your monthly boat payment based on price, down payment, interest rate, and loan term.
- Boat HIN Decoder
Read a boat’s 12-character hull identification number: maker’s code, serial number, build date and model year.
Converters
The units boaters meet: speed in knots, distance in nautical miles, depth in fathoms, positions, track files and barometer readings.
Speed
- Knots to MPH Converter
Convert speed between knots and miles per hour. Includes km/h, m/s, and other units.
- Knots to km/h Converter
Convert knots to kilometers per hour and back. One knot is exactly 1.852 km/h.
- MPH to Knots Converter
Convert miles per hour to knots and back. One mile per hour is about 0.869 knots.
Distance
- Nautical Miles Converter
Convert between nautical miles and land miles, kilometers, meters, and more.
- Miles to Nautical Miles Converter
Convert statute miles to nautical miles and kilometers. One mile is about 0.869 nautical miles.
- Nautical Miles to Kilometers Converter
Convert nautical miles to kilometers and back. One nautical mile is exactly 1.852 km.
- Nautical Miles to Meters Converter
Convert nautical miles to meters and back. One nautical mile is exactly 1,852 meters.
- Nautical Miles to Feet Converter
Convert nautical miles to feet and back. One nautical mile is about 6,076.1 feet.
Depth, position and weather
- Fathoms to Feet Converter
Convert depths between fathoms, feet and meters. A fathom is exactly 6 feet.
- Latitude and Longitude Converter
Convert GPS positions between decimal degrees, degrees and decimal minutes, and degrees, minutes and seconds.
- KML to GPX Converter
Turn KML or KMZ files from Google Earth or My Maps into GPX waypoints, routes and tracks, in your browser.
- Barometric Pressure Converter
Convert barometer readings between inches of mercury, millibars (hPa), mmHg and kPa, with the 3-hour trend.
Guides
Reading a chart, the names for the sides of a boat, Google Maps on the water and how long a boat loan can run.
- How to Read a Nautical Chart
Soundings and chart datum, depth contours, rocks and wrecks, buoys and lights, the compass rose and distance.
- Port vs Starboard
Which side of a boat is port and which is starboard, the red and green lights, and the names for bow, stern and beam.
- Google Maps for Boats
What Google Maps can do for boaters, where it stops, and how to measure distance on water in nautical miles.
- How Long Can You Finance a Boat?
Typical boat loan terms, credit score ranges and how the term changes total interest.