Practice gives you a fixed number of untimed questions with immediate answer feedback. Timed Round asks you to complete as many conversions as possible before the round clock expires. Speed Challenge gives every question its own time limit.
The mixed set rotates evenly through kilometers ↔ miles, kilograms ↔ pounds, Celsius ↔ Fahrenheit, centimeters ↔ inches, liters ↔ US liquid gallons, grams ↔ ounces, and meters ↔ feet. Each seven-question cycle contains every unit pair once before the next cycle is shuffled.
Direction can mix both systems or restrict questions to Metric → US Customary or US Customary → Metric. Difficulty changes the source values within each unit pair: Easy uses simpler whole numbers, Medium introduces one decimal place, and Hard can use two decimal places and wider ranges.
Answer Precision controls how your answer is rounded. The app uses the exact relationships from the focused practice sets: 1 mile = 1.609344 km; 1 lb = 0.45359237 kg; °F = (°C × 9/5) + 32; 1 in = 2.54 cm; 1 US liquid gallon = 3.785411784 L; 1 international avoirdupois oz = 28.349523125 g; and 1 ft = 0.3048 m.
Equivalent numeric formatting is accepted. Use the ± button when a temperature conversion requires a negative answer. You can press Enter to submit, P to pause, or Esc to end the current round. Timers pause automatically when the page is hidden.