Hair Calculators
Bundle length shrinkage.
Wavy and curly bundles wear shorter than the number on the package. Enter the length you want and the texture to see what to order. Straight hair needs no allowance. Runs in your browser.
Your bundles
Length to order
Fill the form and press Calculate.
Worked example
Vinisay says a 20 inch body wave sits closer to 16 to 17 inches once installed, which is 15% to 20% shorter. At the 17.5% midpoint, a 20 inch target installs at 16.5 inches (3.5 inches lost) if you order 20. To land at 20 inches the tool computes 20 / (1 - 0.175) = 24.2 inches, so order 25 (range 23.5 to 25). Vinisay’s own advice is smaller, order 22 for a true 20 inch look, which at 17.5% installs near 18.2 inches. The two do not match, which is why this page shows both.
How it works
shrinkage % comes from the texture you pick: 0 for straight, 15% to 20% for body wave (from the 20 inch example above), or the number you type for custom. Length to order = target / (1 - shrinkage). Installed length = ordered length x (1 - shrinkage). The page rounds the order length up to the next whole inch.
The percent model is our simplification: real shrinkage depends on the wave pattern, how the hair is worn and stretched, and the seller. A shorter order such as target + 2 inches is cheaper but leaves the hair shorter than the target.
Sources and basis
Checked 2026-10-15. Vinisay: How Many Bundles for a Sew-In? Length Chart: a 20 inch body wave sits closer to 16 to 17 inches once installed; if you want a true 20 inch look, order 22; straight hair is the only texture that measures true to length; deep wave shrinks even more than body wave. HookedOnBundles: How Many Bundles Do You Need for a Sew-In?: wavy and curly textures can appear shorter once installed because their pattern takes up space. No seller figure for deep wave or curly was found, so the custom percent is yours.
These are rule-of-thumb estimates from seller and salon guides, not a published standard or professional advice. Confirm the plan with your stylist.
FAQ
How much does body wave hair shrink?
Vinisay gives one example: a 20 inch body wave sits closer to 16 to 17 inches once installed, which is about 15 to 20 percent shorter. Other sellers may differ.
How much does deep wave shrink?
Vinisay says deep wave shrinks even more than body wave but gives no figure, and we found no seller who does. Use the custom box with your own estimate.
Does straight hair shrink?
Vinisay says straight is the only texture that measures true to length, so no allowance is added.
Why do my bundles look shorter than I ordered?
HookedOnBundles notes that wavy and curly textures can appear shorter once installed because the pattern takes up space. The length on the package is measured with the hair pulled straight.
What length bundles should I order?
Divide the length you want by one minus the shrinkage. For a 20 inch result from body wave at 17.5 percent shrinkage that is about 24.2 inches, while Vinisay suggests going up to 22 as a smaller step.