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LJ HairLab

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Trim Schedule Calculator

Find out how often to trim natural or relaxed hair from the state of your ends — and see exactly how much length each schedule costs you in a year.

Check your ends

Split ends

In good light, hold a stretched section of ends against a contrasting background. Look for ends that fork, look frayed or thin, or have tiny white dots.

Single-strand knots (fairy knots)

Tiny knots near the ends of a single hair — common on curly and coily hair.

Heat styling
Chemical treatments
Your goal
Last trim, growth and retention
in

Default 0.5 in (1.27 cm). Use your own measured rate if you have one.

80%

Share of growth you keep after breakage. 100% = no breakage.

in

Add it to carry your trim plan into the growth calculator.

How to use the Trim Schedule Calculator

  1. Check your ends

    In good light, look at a stretched section of ends and choose how many split ends and single-strand knots you see.

  2. Add heat, chemicals and your goal

    Pick how often you use heat, whether your hair is relaxed or colored, and whether you are growing length or keeping a cut.

  3. Fine-tune if you like

    Open “Last trim, growth and retention” to set the date of your last trim, your growth rate, retention, and (optionally) your current length.

  4. Press “Get my trim schedule”

    You get how often to dust or trim, how much to take off, your next trim dates and how much length each schedule costs in a year.

  5. Save the dates

    Add the trims to your phone calendar, download the PDF, or open the growth calculator with your trim plan filled in.

How to use the Trim Schedule Calculator (56 s)

How it works

How often to trim natural hair depends on how fast your ends wear out, not on a fixed rule. The calculator scores what wears them out, turns that score into an interval, and then shows the trade-off in inches.

1. A wear score from your ends

Split ends count most (0–4 points), then single-strand knots (0–2), heat styling (0–3) and chemical processing (0–1). Tightly coiled hair tends to knot and break at the ends during grooming, and heat and chemicals make the oldest part of the strand more fragile — so each adds to the score.

2. Score → interval

A score of 0–1 means you can wait about 16 weeks; 2–3 about 14; 4–5 about 12; 6–7 about 10; and 8 or more, 8 weeks. If you are keeping a cut or shape, the interval is capped at 10 weeks (8 if your ends are worn), because shapes grow out.

3. Dust or trim

For a length goal the default is a dust — ⅛ to ¼ inch. A real trim of ½ to 1 inch is suggested when you are keeping a shape or have lots of knots. If you have many split ends, you'll get a one-time reset trim first, because dusting can't fix splits that run several inches up.

4. The yearly cost in inches

The table under your result uses the same formula as our hair growth calculator: growth × retention − trim × (4.345 ÷ weeks between trims), times 12. For the math we use the top of each range (¼ inch for a dust, ½ inch for a trim), so the numbers never look better than they are.

Limits

  • Trims don't speed up growth. They protect retention by removing damage before it travels.
  • “No trims” looks best on paper, but splits and knots that stay usually break off on their own.
  • The score is a practical guide, not a diagnosis. Sudden breakage or shedding is worth a dermatologist visit.

How much length common trim schedules cost

Schedule Cut off per year Kept at 70% retention Kept at 80% Kept at 90%
⅛″ every 16 weeks 0.4″ 3.8″ 4.4″ 5″
¼″ every 16 weeks 0.8″ 3.4″ 4″ 4.6″
¼″ every 12 weeks 1.1″ 3.1″ 3.7″ 4.3″
½″ every 12 weeks 2.2″ 2″ 2.6″ 3.2″
½″ every 8 weeks 3.3″ 0.9″ 1.5″ 2.1″
1″ every 12 weeks 4.3″ −0.1″ 0.5″ 1.1″
1″ every 8 weeks 6.5″ −2.3″ −1.7″ −1.1″

At 0.5″ (1.27 cm) of growth a month. Retention is the share of growth you keep after breakage.

Typical schedules by condition

Your ends Length goal Shape goal How much
Healthy ends, no heat, natural Every 16 weeks Every 10 weeks Dust ⅛–¼″
A few splits or knots, monthly heat Every 14 weeks Every 10 weeks Dust ⅛–¼″
A few splits, weekly heat, relaxed or colored Every 12 weeks Every 10 weeks Dust ⅛–¼″
Many splits, weekly heat Every 10 weeks Every 8 weeks Reset trim, then dust
Many splits, lots of knots, frequent heat, processed Every 8 weeks Every 8 weeks Reset trim, then trim ½–1″

Frequently asked questions

How often should you trim natural hair?
Most people land somewhere between every 8 and 16 weeks. Healthy ends with little heat can go 3–4 months between light dusts; frequent heat, color, relaxers or lots of split ends and knots call for every 8–12 weeks. Use the checker above to see where you fall.

Does trimming make your hair grow faster?
No. Hair grows from the follicle in your scalp, and cutting the ends doesn’t change that speed. What trims can do is remove split ends before they travel up the strand and break off more length — so they can help you keep more of what you grow.

What is the difference between dusting and trimming?
Dusting takes off only the very tips — about ⅛ to ¼ inch — often on stretched hair or twists, so you lose almost no length. A trim removes ½ inch or more to cut away damage or keep a shape. Many people dust regularly and trim only when the ends are clearly worn.

How do I know if I need a trim?
Signs include split or frayed ends, single-strand knots, ends that tangle and snag every wash day, ends that look thin or see-through compared with the rest of your hair, and twist-outs that won’t hold at the ends.

How much hair should I cut off?
Cut just above where the damage stops. If you only see a few splits, a dust is enough. If splits run several inches up, one bigger reset trim is better than many small ones — the calculator flags when you need it.

Can I trim my own natural hair?
Yes, many people do. Use sharp hair shears (not kitchen or craft scissors, which fray the ends), work on stretched hair in small twists or braids, and snip just the ends. If you want a shaped cut, a stylist who works with your texture is the safer choice.

How often should relaxed hair be trimmed?
Relaxed ends are the oldest and most processed part of the hair, so they often need attention every 8–12 weeks. Many people dust at each touch-up and do a bigger trim only when the ends look thin or split.

Sources

Last data update:

  1. Khumalo NP, Doe PT, Dawber RP, Ferguson DJ. What is normal black African hair? A light and scanning electron-microscopic study. J Am Acad Dermatol. 2000;43(5 Pt 1):814-820. Tightly coiled hair forms knots and breaks more easily during grooming.
  2. Bryant H, Porter C, Yang G. Curly hair: measured differences and contributions to breakage. Int J Dermatol. 2012;51 Suppl 1:8-11. Curlier hair breaks more during combing; breakage is a key limit on length.
  3. Robbins CR. Chemical and Physical Behavior of Human Hair. 5th ed. Springer; 2012. Reference text on hair structure, surfactants, conditioning agents, protein, heat and chemical treatments.
  4. Loussouarn G. African hair growth parameters. Br J Dermatol. 2001;145(2):294-297. Afro-textured hair grew about 256 µm/day in the study sample — slower than Asian and Caucasian samples.

How we research and update pages: editorial policy. Spotted an error? Tell us.

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