Contraction Timer Calculator

How it is calculated

The interval is the number of minutes from the start of one contraction to the start of the next; the duration is how long a single contraction lasts, in seconds. The tool shows the interval as a frequency, "every N min", then compares your two numbers with the 5-1-1 rule using fixed thresholds: interval ≤ 5 min and duration ≥ 60 s. Both met gives the "meets 5-1-1" message; an interval of 5 minutes or less with shorter contractions gives "frequent, monitor"; an interval above 5 minutes gives "early labor". Interval and duration must be above zero, and a negative count is rejected. The optional count per hour is accepted but does not change the message, and the tool cannot check that the pattern has lasted a full hour. It is an information aid, not medical advice.

Common mistakes

• Measuring the interval from the end of one contraction to the start of the next. The interval is start to start, so it includes the contraction itself.
• Entering the duration in minutes. The field is in seconds, so a one-minute contraction is 60, not 1.
• Using a single pair of contractions. The rule describes a sustained pattern, so time several in a row and enter the average.
• Expecting the count per hour to change the verdict. Only interval and duration are compared; the one-hour requirement is yours to track.
• Relying on the message instead of your care provider's advice. A timer cannot assess you; if you are worried or unsure, call your midwife or doctor whatever it says.