How do I estimate mph to knots mentally?

Rough estimate: multiply by 0.87 (or divide by 1.15). Example: 30 mph ÷ 1.15 ≈ 26 knots. For precision, divide by 1.15078.

A fishing guide says the boat can do 35 mph max speed. What does that translate to in knots for planning a day trip?

35 mph = 30.4 knots. If you're heading 20 nautical miles out and 20 back, that's 40 nautical miles total; at 30 knots you'll spend about an hour and 20 minutes on the water (not counting refueling or delays).

I'm reading weather data that says wind speeds of 60 mph in a tropical storm. What's that in knots?

60 mph = 52.1 knots. For the reverse conversion, see knots to mph.

Miles per Hour (mph) to Knots Converter

Enter a value to instantly convert between speed units.

From

Precision4 dp

1 Mile per Hour = 0.869 Knot

Key Formulas

Kilometer per Hour → Mile per Hour

mph = km/h × 0.621371

Mile per Hour → Kilometer per Hour

km/h = mph × 1.60934

Knot → Mile per Hour

mph = kn × 1.15078

Mile per Hour → Knot

kn = mph × 0.868976

Formula

knots = mph ÷ 1.15078

To convert miles per hour to knots, divide by 1.15078. This is useful when reading maritime or aviation specifications, weather reports (hurricane speeds), or nautical navigation instructions.

Source: NIST SP 811, Table B.8

Reviewed by the Convert Calc editorial team · Last reviewed: 2026-10-06 · see our methodology

Frequently Asked Questions

Real-World Examples

Boat speed example. 10 mph is about 8.7 knots.

10 mph = 8.69 kn

A boat at 20 mph travels about 17.4 knots.

20 mph = 17.38 kn

Example speed of 30 mph, about 26 knots.

30 mph = 26.06 kn

Vessel speed example. 100 mph is about 86.9 knots.

100 mph = 86.9 kn

kmh to mph mph to kmh knots to mph ms to kmh kmh to ms

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