Cycle phase calculator / Cycle day 3

Cycle day 3: what phase am I in?

On a 28-day cycle, day 3 is usually the menstrual phase. It falls in the menstrual phase on every typical cycle length.

By day 3 most women are past the worst of the cramps. Estrogen is beginning to edge up from its low point, though you will rarely feel it yet.

Day 3 across different cycle lengths

Assumes a 5-day period and a 14-day luteal phase, the same model the Phaes app uses. Your own cycle can vary by a few days from month to month.

What is happening in your body

Estrogen and progesterone are at their lowest point of the cycle. The drop in progesterone is what triggers the period. Cramps, low energy and a heavier-feeling body are common in the first day or two, though plenty of women feel completely normal.

Energy often starts low and lifts as the bleed eases.

How to train on day 3

Running

Keep it gentle if you feel rough: an easy run, a walk, cross-training, or a rest day. If you feel good, an easy or steady run is fine.

Strength

Lift, but ease the top-end effort. Phaes deloads the heaviest sets this phase so you recover.

Fuel

Iron matters if your periods are heavy: red meat, lentils, beans and leafy greens, with vitamin C to help absorption.

Treat this as a starting point. A meta-analysis of 78 studies found that cycle phase has at most a trivial effect on performance on average, with big differences between women (McNulty et al., 2020). How you slept and how you feel today should win.

If your cycles are changing

In perimenopause cycles get shorter, then longer and less predictable, and ovulation does not happen every month, so a day number stops telling you much about your hormones. The training answer changes too: short sprints over long slow miles, lifting heavy, easy days that are genuinely easy, one full rest day a week and a reset week every fourth week. Take the perimenopause quiz if you are not sure where you are.

Questions women ask about day 3

What phase is day 3 of my cycle?

On a 28-day cycle, day 3 is usually the menstrual phase. It falls in the menstrual phase on every typical cycle length.

Should I work out on day 3 of my cycle?

Yes, if you feel up to it. Keep it gentle if you feel rough: an easy run, a walk, cross-training, or a rest day. If you feel good, an easy or steady run is fine.

How should I lift weights on cycle day 3?

Lift, but ease the top-end effort. Phaes deloads the heaviest sets this phase so you recover.