What is a normal hair growth rate per month?

A commonly cited average for scalp hair is about 1.25 cm per month (roughly 0.5 inches, or 15 cm per year). Individual rates vary by genetics, age, hormones, health, and ethnicity. The best approach is to track your own growth for 8–12 weeks consistently to establish your personal baseline rate.

Why does my hair "grow" but I do not gain length?

This is the classic retention problem. Hair grows from the scalp, but you measure length at the ends. Breakage, split ends traveling upward, friction damage, and trimming can remove length faster than new growth arrives, creating a stalled or declining length. Model breakage and trims to see the real picture.

Do trims actually make hair grow faster?

No. Trims do not change your follicle growth rate. Removing split ends *may* help retention by preventing upward splitting, which can improve length gains indirectly. But each trim also removes length immediately. The key is balance: trim often enough to protect health, infrequently enough that growth outpaces removal.

How should I measure my hair length for consistent tracking?

Pick one spot and stick to it (e.g., crown, longest point, or front edge). Use the same method each time: same stretch, same tool, same hair state (damp vs dry). Hair length is affected by water content and styling, so consistency matters more than "perfect" precision. Monthly checks are enough for meaningful tracking.

Is daily shedding normal? How much is too much?

Shedding 50–100 hairs daily is normal and expected — it is just the telogen phase exiting the follicle. Temporary increases happen during stress, postpartum, after illness, hormonal shifts, or seasonal changes. If shedding is sudden, concentrated in patches, or accompanied by scalp pain, professional evaluation is wise.

Can diet, supplements, or stress really affect hair growth?

Yes, both can matter. Severe malnutrition, deficiencies (iron, B12, protein, zinc), chronic high stress, and poor sleep can all slow growth or increase shedding. Conversely, consistent nutrition, stress management, and sleep can support healthy growth. This calculator includes a health/lifestyle modifier to reflect this. Results are not dramatic but meaningful over months.

What about hair growth "hacks" or supplements?

Many "growth" supplements exist; most have limited evidence for healthy people with normal nutrition. Biotin, collagen, and general multivitamins are common, but studies show modest or no benefit in people without deficiencies. The basics — consistent nutrition, hydration, sleep, stress management, and mechanical care — matter most.

Is this calculator medical advice?

No. This is an educational planning tool for tracking and projecting personal hair growth using self-reported inputs. It is not a diagnosis. If you experience sudden shedding, patchy loss, scalp pain, significant thinning, or unusual changes, consult a licensed dermatologist or clinician.

Health Calculator

Hair Growth Calculator

This calculator estimates a personalized monthly hair growth rate by accounting for key demographic and biological factors including age, ethnicity, overall health, and stress levels. It then adjusts this baseline rate for real-world physical factors—breakage and maintenance trims—to project actual length retention over time. Use this tool to estimate time-to-goal and understand the variables affecting your net hair growth.

Hair Growth

Project length, estimate time-to-goal, and model retention

Units

Time Unit

Current Hair Length

Measure scalp-to-tip (pick a consistent spot like crown).

Projection Period

Use weeks for short tracking, months/years for goals.

Target Length (optional)

If set, we estimate time-to-goal using your effective rate.

Personalization

Age Group

Gender

Ethnicity / Hair Type (growth-rate factor)

Nutrition Quality

Stress Level

Sleep Quality

Hormonal Status (optional)

Heat / Chemical Treatments

Protective Styling Frequency

Retention (Breakage + Trims)

Breakage Input

Trim Schedule

Breakage (retention loss)

10% means you keep ~90% of new length before trims.

Trim Every

0 = no trims

Trim Amount

What you remove each trim

Expert note: most “my hair won’t grow” complaints are actually retention problems. Use breakage + trims to model what you truly keep.

Past Growth Calibration (optional)

Rate Mode

My Hair Grew

Example: 3 inches

Over

Example: 6 months

Results

Enter your hair details to project growth

What This Hair Growth Calculator Tells You

After answering questions about your demographics, health, care habits, and current retention practices, this calculator returns:

Projected length after your chosen time period (weeks, months, or years)
Raw monthly growth rate (before breakage and trims)
Effective monthly rate (what you actually keep after breakage and trims)
Confidence range showing how much individual variation exists
Time to target length (if you set a goal)
Milestone projections at 1, 3, 6, 12, 18, and 24 months

Core Formulas

The math is intentionally transparent so you can understand and adapt the estimates to your own data.

Growth = Monthly Rate × Time Period

Personalized Rate = Base (1.25 cm/mo) × Ethnicity × Age × Gender × Health Factor

Effective Rate = Raw Rate − Breakage Loss − Trim Loss

Time to Target = (Target Length − Current) ÷ Effective Rate

Typical Monthly Growth Rates by Ethnicity & Hair Type

Research shows meaningful variation in average growth rates. These are population-level ranges — your personal rate can differ significantly based on age, genetics, health, and individual biology.

Ethnicity / Hair Type	Range (cm/mo)	Annual (cm)	Context & Notes
Asian	1.75–2.13	21–26	Fastest reported average; typically straight or wavy
Caucasian	1.38–1.63	17–20	Most studied population; moderate variability
African	1.00–1.25	12–15	Often slower due to curl pattern and fragility
Mixed / Other	1.19–1.44	14–17	Highly variable; depends on specific genetics

Important: These ranges reflect published research averages. Individual variation is substantial — genetics, hormones, age, and health status can shift your personal rate significantly. Track your own growth over 8–12 weeks to find your baseline.

The Hair Growth Cycle (Why Progress Isn't Linear)

Hair does not grow indefinitely without interruption. Each follicle enters a multi-year cycle with distinct phases. Understanding this explains seasonal shedding, growth plateaus, and why individual hairs "live" different lengths.

Phase	Duration	% of Scalp	What Happens
Anagen (Growth)	2–8 years	85–90%	Hair actively grows. Visible growth of ~0.35–0.4 mm daily; ~1.25 cm monthly average.
Catagen (Transition)	~2 weeks	<1%	Follicle shrinks. Connective tissue separates. Brief bridge between growth and rest.
Telogen (Rest)	2–3 months	10–15%	Hair stops growing, anchored loosely. Follicle prepares to release the old hair.
Exogen (Shed)	Variable	Active	Old hair releases naturally. New anagen hair begins emerging from same follicle.

Shedding is normal: Daily loss of 50–100 hairs is expected as telogen hairs exit. Temporary spikes can occur during stress, postpartum, seasonal changes, or after illness. If shedding is sudden, concentrated, or accompanied by scalp symptoms, seek professional evaluation.

Retention: The Real Limiter (Breakage + Trims)

This is where most "my hair won't grow" frustrations live. Hair can be growing at the scalp while your measured length stays flat or shrinks. Why? Because you measure length at the ends, not the scalp.

Effective Growth = Raw Growth − Breakage − Trims

Breakage (friction, dryness, chemicals): Every day, ends split and shed. Curly and textured hair is more prone. Calculate as % of monthly growth lost, or track in absolute length.

Trims (maintenance & damage removal): Cutting blunt ends helps retention by preventing upward split travel. But each trim also removes length *now*. Balance: trim enough to protect, infrequently enough that growth outpaces cuts.

Expert Tip: Start With 10% Breakage

If you're not sure about breakage, use 10% as a placeholder. Track your actual length monthly for 6–8 weeks, compare it to the calculator's projection, and adjust the breakage % until the model matches your real results. This calibration makes future projections much more useful.

Example Scenarios

Use these examples to understand how personalization, breakage, and trims interact to drive real-world outcomes.

Example 1 — Personalized estimate (12-month projection)

Current: 20 cm • Time: 12 months • Profile: 28-year-old Caucasian female • Good nutrition • Low stress

Base average ≈ 1.25 cm/month

Apply profile factors (age + hair type + health/lifestyle) ≈ 1.4 cm/month personal rate

Projected growth = 1.4 × 12 ≈ 16.8 cm

With 10% breakage + trims: effective ≈ 1.25 cm/month → 15 cm actual gain

Example 2 — Simple average estimate (inches)

Average rate: 0.5 in/month • 6-month period • No trims, minimal breakage

Growth = 0.5 × 6 = 3 inches

Projected length = 12 in + 3 in = 15 inches

Compare with your actual measurement after 6 months to calibrate

Example 3 — Retention limits progress (common scenario)

Same rate (0.5 in/month), but 25% breakage + trim 0.25" every 12 weeks

Raw growth in 6 months = 0.5 × 6 = 3 inches

After 25% breakage loss = 2.25 inches net growth

Trim loss = 3 trims × 0.25 in = 0.75 inches removed

Effective gain = 3 − 2.25 − 0.75 = 0 inches (stalled, despite growth)

Frequently Asked Questions

What is a normal hair growth rate per month?: A commonly cited average for scalp hair is about 1.25 cm per month (roughly 0.5 inches, or 15 cm per year). Individual rates vary by genetics, age, hormones, health, and ethnicity. The best approach is to track your own growth for 8–12 weeks consistently to establish your personal baseline rate.
Why does my hair "grow" but I do not gain length?: This is the classic retention problem. Hair grows from the scalp, but you measure length at the ends. Breakage, split ends traveling upward, friction damage, and trimming can remove length faster than new growth arrives, creating a stalled or declining length. Model breakage and trims to see the real picture.
Do trims actually make hair grow faster?: No. Trims do not change your follicle growth rate. Removing split ends *may* help retention by preventing upward splitting, which can improve length gains indirectly. But each trim also removes length immediately. The key is balance: trim often enough to protect health, infrequently enough that growth outpaces removal.
How should I measure my hair length for consistent tracking?: Pick one spot and stick to it (e.g., crown, longest point, or front edge). Use the same method each time: same stretch, same tool, same hair state (damp vs dry). Hair length is affected by water content and styling, so consistency matters more than "perfect" precision. Monthly checks are enough for meaningful tracking.
Is daily shedding normal? How much is too much?: Shedding 50–100 hairs daily is normal and expected — it is just the telogen phase exiting the follicle. Temporary increases happen during stress, postpartum, after illness, hormonal shifts, or seasonal changes. If shedding is sudden, concentrated in patches, or accompanied by scalp pain, professional evaluation is wise.
Can diet, supplements, or stress really affect hair growth?: Yes, both can matter. Severe malnutrition, deficiencies (iron, B12, protein, zinc), chronic high stress, and poor sleep can all slow growth or increase shedding. Conversely, consistent nutrition, stress management, and sleep can support healthy growth. This calculator includes a health/lifestyle modifier to reflect this. Results are not dramatic but meaningful over months.
What about hair growth "hacks" or supplements?: Many "growth" supplements exist; most have limited evidence for healthy people with normal nutrition. Biotin, collagen, and general multivitamins are common, but studies show modest or no benefit in people without deficiencies. The basics — consistent nutrition, hydration, sleep, stress management, and mechanical care — matter most.
Is this calculator medical advice?: No. This is an educational planning tool for tracking and projecting personal hair growth using self-reported inputs. It is not a diagnosis. If you experience sudden shedding, patchy loss, scalp pain, significant thinning, or unusual changes, consult a licensed dermatologist or clinician.