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.
Difficulty changes the lengths being converted. Easy uses whole numbers from 5–100 cm or 2–40 inches. Medium uses one decimal place from 5.0–300.0 cm or 2.0–120.0 inches. Hard can use two decimal places from 2.00–1000.00 cm or 0.75–400.00 inches.
Answer Precision controls how your answer is rounded. One inch equals exactly 2.54 centimeters. To convert centimeters to inches, divide by 2.54; to convert inches to centimeters, multiply by 2.54. The app uses exact rational arithmetic, then checks whether your numeric answer rounds to the required precision.
When Both Directions is selected, questions alternate unpredictably between centimeters-to-inches and inches-to-centimeters. Equivalent numeric formatting is accepted, so an answer such as 62.10 is treated the same as 62.1 when appropriate.
You can press Enter to submit, P to pause, or Esc to end the current round. Timers pause automatically when the page is hidden.