Understanding your menstrual flow is one of the most important steps in finding the right cup. Your flow level directly affects what cup capacity you need. Choose a cup that's too small for your flow, and you'll need to empty it constantly. Choose one that matches your needs, and you'll have comfortable, leak-free protection throughout your day.

What Is Flow Level?

Your flow level describes how much blood your body releases during your period. Some women have light periods that barely require protection. Others have heavy flows that need frequent pad or tampon changes. Most women fall somewhere in between.

Flow levels are typically measured in milliliters per day. Here's how the different categories break down:

Flow Category	Approximate Flow (ml/day)	Tampons Used Per Day
Light Flow	0-20 ml	1-4 tampons
Regular Flow	21-25 ml	4-5 tampons
Heavy Flow	26-30 ml	5-6 tampons
Very Heavy Flow	31+ ml	7+ tampons

How to Assess Your Flow

The easiest way to figure out your flow level is to count how many pads or tampons you use per day. Think about your heaviest flow days—usually day one or two of your period.

If you use one to four tampons on your heaviest day, you have a light flow. Four to five tampons means regular flow. Five to six tampons indicates heavy flow. Seven or more tampons means very heavy flow.

Your flow also changes throughout your period. Most women have their heaviest flow in the first two days, then it gets lighter. This is completely normal and affects how often you'll need to empty your cup.

Matching Cup Capacity to Your Flow

Once you know your flow level, you can choose a cup with the right capacity. Cup capacity is measured in milliliters and tells you how much fluid the cup can hold.

Light Flow

Women with light flow do well with smaller capacity cups, usually between 15 and 20 milliliters. These cups are often more comfortable because they're smaller overall. You can wear them for up to 12 hours without worrying about leaks.

Regular Flow

If you have a regular flow, look for cups with 20 to 25 milliliters of capacity. This gives you enough room to go several hours between changes. Most women with regular flow can wear their cup for 8 to 12 hours on heavy days.

Heavy and Very Heavy Flow

Heavy flows need cups with higher capacity—anywhere from 25 to 40 milliliters or more. These larger cups let you go longer between changes even on your heaviest days. Women with very heavy flow might need to empty their cup more frequently, perhaps every 4 to 8 hours on day one or two.

You can learn more about cup sizes and capacity in our chapter on capacity.

How Often Should You Empty Your Cup?

The answer depends on both your flow and your cup's capacity. Here's a simple guide:

Light flow with small cup: Every 8-12 hours
Regular flow with medium cup: Every 8-12 hours
Heavy flow with larger cup: Every 4-8 hours on heavy days
Very heavy flow: Every 4-6 hours on heaviest days, even with a large cup

Remember, you can safely wear a menstrual cup for up to 12 hours. But if you have a heavier flow, you may need to empty it sooner to prevent overflow and leaks.

What Affects Your Flow?

Your flow level isn't set in stone. Several factors can make your periods heavier or lighter over time:

Age: Younger women often have lighter flows that get heavier in their 30s and 40s
Hormones: Birth control, hormonal changes, and menopause can all affect flow
Childbirth: Many women notice changes in flow after having children
Medical conditions: Things like fibroids or endometriosis can cause heavier bleeding
Stress and lifestyle: Exercise, diet, and stress levels can influence your period

If your flow changes significantly or becomes very heavy suddenly, talk to your doctor. Very heavy periods can sometimes indicate a health issue that needs attention.

Finding Your Perfect Match

Knowing your flow level is essential, but it's just one piece of the puzzle. The perfect menstrual cup also depends on your cervix height, age, activity level, and other factors.

Our Cup-Figurator quiz considers all these factors together to recommend the best cup features for your unique body. The quiz takes just a few minutes and gives you personalized recommendations based on your flow and other important measurements.

Key Takeaways

Understanding your flow is simple once you know what to look for. Count your tampons or pads on your heaviest day to determine if you have light, regular, heavy, or very heavy flow. Then choose a cup with the right capacity to match. Light flows need smaller cups around 15-20 milliliters. Heavy flows need larger cups with 25-40 milliliters or more. Match your cup to your flow, and you'll enjoy comfortable, leak-free protection throughout your entire period.