The mph to knots formula
To convert miles per hour to knots, divide by 1.15078: knots = mph ÷ 1.15078. For example, 100 mph ÷ 1.15078 = 86.90 knots. A knot is one nautical mile per hour. To reverse it, use the knots to mph calculator.
The factor comes from the units underneath: a nautical mile is exactly 1,852 metres while a statute mile is 1,609.344 metres, and 1852 divided by 1609.344 is 1.15078. For a rough mental check, knock about 13% off an mph figure - 60 mph is close to 52 knots.
If the next number you need is a related one, the km to miles calculator covers it.
How to convert mph to knots
Enter a speed in miles per hour and the calculator divides by 1.15078 to give knots. Knots are used in aviation, marine navigation, and meteorology because a nautical mile maps neatly to one minute of latitude.
The nautical mile is defined as one minute of latitude, so a vessel travelling 1 knot for one hour covers exactly one minute of arc on a chart. That makes distance, time and position work directly from the chart scale with no conversion at all, which is why navigators keep the unit. Weather services use it too: a gale warning at 34 knots is 39 mph, and hurricane force at 64 knots is 74 mph.
Pair this with the mph to km/h calculator when you need the fuller picture.
MPH to knots reference table
| MPH | Knots |
|---|---|
| 10 mph | 8.69 knots |
| 50 mph | 43.45 knots |
| 100 mph | 86.90 knots |
| 200 mph | 173.80 knots |
Useful anchors either way: 1 knot is 1.15078 mph or 1.852 km/h, a cruising yacht at 6 knots is doing 6.9 mph, and an airliner at 500 knots is doing 575 mph. Always label the figure, because a speed quoted without its unit is the source of most navigation errors.
The km/h to mph calculator handles the closely related case.
Frequently asked questions
- What is 100 mph in knots?
- 100 mph equals 86.90 knots (100 ÷ 1.15078).
- What is the mph to knots formula?
- knots = mph ÷ 1.15078.
- Why is a knot faster than mph?
- A knot is one nautical mile per hour, and a nautical mile (1.852 km) is longer than a statute mile (1.609 km).
- How do I convert knots back to mph?
- Multiply by 1.15078, or use the knots to mph calculator.
- Should I say knots or knots per hour?
- Just knots. A knot already means one nautical mile per hour, so 'knots per hour' would describe an acceleration, not a speed. It is the most common slip when people first move from mph to marine and aviation units.