Miles per Hour to Knots

What is the mph to Knots Converter?

This converter transforms miles per hour into nautical knots, the standard speed unit for marine navigation. It helps recreational boaters transition from thinking in mph to using the professional nautical measurement system.

While you might know your boat does 35 mph, marine charts, weather forecasts, and professional mariners communicate in knots. Learning to work in knots makes navigation more intuitive and helps you communicate effectively on marine radio.

Who Needs This Conversion?

• New boat owners - Transitioning from cars to marine navigation
• Boating course students - Learning nautical fundamentals
• Charter captains - Communicating with harbormasters and Coast Guard
• Fishing tournament participants - Working with official marine measurements
• Navigation planners - Calculating trip times with nautical charts

Why Knots Matter

Nautical charts use nautical miles, and speed in knots makes distance calculations simple. At 10 knots, you cover 10 nautical miles per hour. This direct relationship simplifies voyage planning compared to converting between mph and statute miles.

How to Use the mph to Knots Converter

Converting your familiar mph speeds to knots takes just seconds.

Quick Guide

1. Enter mph - Type your boat's speedometer reading
2. See knots - The nautical equivalent appears instantly
3. Use for planning - Apply to chart distances and trip calculations

Common Boat Speeds

Reference speeds for different vessel types:

• Trolling: 3-5 mph = 2.6-4.3 knots
• Sailboat cruising: 5-8 mph = 4.3-7 knots
• Pontoon boat: 20-25 mph = 17-22 knots
• Fishing boat: 25-35 mph = 22-30 knots
• Speedboat: 50-70 mph = 43-61 knots

Trip Planning Example

If your destination is 30 nautical miles away and your boat cruises at 25 mph (21.7 knots), divide 30 by 21.7 to get approximately 1.4 hours travel time. Working in knots makes this calculation straightforward.

Marine Radio Communication

When Coast Guard or other vessels ask your speed, respond in knots. Knowing your typical cruising speed in knots before you need it prevents confusion during important communications.

Features

Instant Conversion

Results appear immediately as you type. Quickly check different speeds to understand the relationship between mph and knots for your typical boat operations.

Precise Calculation

Using the exact factor (1 mph = 0.868976 knots), the converter provides accurate results. This precision matters when planning longer voyages or fuel consumption.

Speed Reference Table

Common boat speeds are pre-calculated for quick reference. See typical trolling, cruising, and maximum speeds in both units without individual calculations.

Bidirectional Swap

Switch to knots-to-mph conversion with one click. Useful when you encounter a knot speed and want the mph equivalent you're familiar with.

Nautical Context

Information cards explain why knots exist and their relationship to nautical miles. Understanding the system's logic helps you adopt nautical thinking more naturally.

Mobile Accessibility

Access from any device at the marina, on the dock, or aboard your vessel. The responsive design works well on phones and tablets.

Offline Functionality

Once loaded, works without internet connection. Reliable even in areas with poor cell coverage common around waterways.

Frequently Asked Questions

How do I convert mph to knots in my head?

Multiply by 0.87, or subtract about 13% from the mph value. For example, 30 mph - 13% (4) = approximately 26 knots. The exact value is 26.1 knots.

Should I change my boat GPS to show knots?

Yes, if you use nautical charts. When your GPS shows knots and charts measure nautical miles, calculating arrival times becomes simple division without conversion.

What speed should I report to Coast Guard?

Always report speed in knots when communicating with Coast Guard or other vessels on marine radio. They use nautical measurements exclusively.

Is there a difference between air knots and water knots?

No, a knot is always 1 nautical mile per hour (1.852 km/h or 1.151 mph) whether on water or in the air. Both industries use the same definition.

How fast is "no wake" speed in knots?

No wake zones typically require speeds under 5 mph (4.3 knots). At this speed, your boat produces minimal wake that won't damage docks or disturb other vessels.

Why do some boats show both mph and knots?

Many recreational boat speedometers display both units because owners may be more familiar with mph, while charts and official communications use knots.