The most expensive mistake in extension work isn't a bad color match — it's ordering the wrong amount of hair. Under-order and the ends look stringy. Over-order and you've tied up cash, added tension to fine hair, and created a maintenance headache. Here's how to get it right the first time.
Full-head gram weight by length
These ranges assume a full-head install adding both length and volume on medium-density natural hair. Read the low end for length-only goals and the high end for maximum density.
- 18": 100g for length only; 120–150g for length plus volume.
- 20–22": 120g for length only; 140–160g for length plus volume.
- 24–26": 160g for length only; 200–240g for length plus volume.
- 28–30": 200g for length only; 240–300g for length plus volume.
- Volume only, current length: 50–80g regardless of the length ordered.
Why longer hair needs more grams
A strand of hair tapers toward the tip. When you go longer, the same number of strands spreads thinner at the ends, so the look reads sparse unless you add weight to compensate. That's why a 28" install can need nearly double the grams of an 18" install for the same visual fullness.
How density changes the number
The ranges above are a starting point for medium density. Adjust from there: fine or low-density hair stays at or below the low end, since the goal is a seamless blend rather than maximum weight; medium density uses the ranges as written; and thick or coarse hair plans for the high end or beyond, especially past 24", to blend all the way to the ends.
Does the format change how much you need?
Slightly. Wefts and tape-ins lay flat and cover efficiently, so they can use marginally less than clip-in style spreads for the same coverage. Bulk hair for hand-tied or fusion work is measured the same way by gram weight. The length and density of the natural hair drive the number more than the format does.
