Convert knots to miles per hour and back. Shows km/h, m/s, Mach, Saffir-Simpson hurricane category, and speed comparison visuals.
The knots to mph calculator converts between nautical speed (knots) and statute miles per hour. One knot equals 1.15078 mph. The tool also outputs km/h, m/s, ft/s, and Mach number, plus identifies the Saffir-Simpson hurricane category for the given wind speed.
Preset buttons include common maritime, aviation, and weather scenarios from light wind to jet cruise speed. A visual speed comparison bar places your input alongside walking, cycling, highway, and the speed of sound for intuitive context.
The Saffir-Simpson hurricane scale table highlights your current category, making this calculator especially useful during tropical weather season when forecasts report wind in knots but the public thinks in mph. Check the example with realistic values before reporting. Use the steps shown to verify rounding and units. Cross-check this output using a known reference case. Use the example pattern when troubleshooting unexpected results. Validate that outputs match your chosen standards. Run at least one manual sanity check before publishing.
Maritime weather uses knots while US road and weather reports use mph. When a forecast says "sustained winds 64 knots," you need to know that means 74 mph — a Category 1 hurricane. This tool makes the conversion instant and keeps the storm-scale context visible so you can interpret wind speeds without doing the math by hand.
mph = knots × 1.15078. knots = mph ÷ 1.15078. 1 knot = 1 nautical mile/hour = 1.852 km/h.
Result: 64 kt = 73.6 mph = 118.5 km/h — Category 1 Hurricane
64 × 1.15078 = 73.65 mph. This is the minimum threshold for a Category 1 hurricane on the Saffir-Simpson scale.
Pilots report airspeed in knots indicated airspeed (KIAS) and true airspeed (KTAS). At altitude, thinner air means KTAS exceeds KIAS. A jet at FL350 might indicate 280 KIAS but fly at 480 KTAS. ATC and flight plans use knots exclusively.
Developed in 1971, the scale originally included storm surge and flooding estimates. Since 2010, it uses only wind speed: Cat 1 (64–82 kt), Cat 2 (83–95 kt), Cat 3 (96–112 kt), Cat 4 (113–136 kt), Cat 5 (≥137 kt). Major hurricanes (Cat 3+) cause the most destruction.
A cargo ship cruises at 12–15 knots (14–17 mph). A fast ferry does 30–40 knots (35–46 mph). Racing sailboats hit 30+ knots, and hydrofoils exceed 50 knots. The fastest naval craft (hovercraft) reach ~60 knots.
1 knot = 1.15078 mph. Conversely, 1 mph = 0.86898 knots.
Multiply by 1.15078, or simply add about 15%. Example: 100 knots × 1.15078 = 115.1 mph.
Nautical miles are based on Earth geometry (1 NM = 1 minute of latitude), making navigation math simpler. Aviation and maritime industries adopted knots for this practical advantage.
The Saffir-Simpson Hurricane Wind Scale classifies hurricanes into 5 categories based on sustained wind speed: Cat 1 (64–82 kt), up to Cat 5 (≥137 kt). It estimates potential property damage.
A tropical storm has sustained winds of 34–63 knots = 39–73 mph. Below 39 mph is a tropical depression; at 74 mph it becomes a hurricane.
A nautical mile is distance (1.852 km). A knot is speed (1 nautical mile per hour). "The ship travels at 20 knots" means 20 nautical miles per hour.