Hair extension cost.

Worked example

100 strands at 1 g each is 100 g (3.53 oz). With 10% spare you need 110 g. At 50 g a pack that is 2.2 packs, rounded up to 3 packs. At $80 a pack the hair is $240, with 50 g left over. Add a $300 install and the first set costs $540, or $5.40 per strand. Reinstalled every 3 months that is 4 installs a year, $2,160 a year if you buy new hair each time.

How it works

total grams = strands x grams per strand. packs = round up(total grams x (1 + spare %) / grams per pack). hair cost = packs x pack price; total cost = hair cost + install fee; cost per strand = total cost / strands. yearly cost = total cost x 12 / months between reinstalls.

No strand count is assumed. The amount you need depends on the method (keratin tips, tape-ins, sew-in wefts, clip-ins), your own hair density and the look you want, so use the number your installer or the product listing gives you. If you reuse hair at reinstall, enter only the new hair; the yearly figure assumes you buy it all again.

Sources and basis (checked 2026-10-05): arithmetic on the figures you enter. Ounce conversion 1 oz = 28.349523125 g (NIST).

FAQ

How many packs of hair extensions do I need?

Multiply the strand count by the grams per strand, add a little spare, then divide by the grams in a pack and round up. 100 strands of 1 g with 10% spare is 110 g, or 3 packs of 50 g.

How many grams of extensions do I need?

It depends on method, hair density and the look you want, so there is no single number. Use the strand or weft count from your installer and the weight from the listing.

How do I find the cost per strand?

Add the hair cost and the install fee, then divide by the number of strands.

How much do extensions cost per year?

Total cost x 12 / months between reinstalls. Enter the reinstall interval to see it. If you reuse your hair at reinstall, your real yearly cost is lower.

Why add spare hair?

Strands get trimmed, blended or damaged in installation. 10% is a common cushion; set 0 if you want the exact need.