---
title: "What Is Visible transmittance (VT)? Window and Door Glossary"
description: "Visible transmittance, or VT, is a number from 0 to 1 that shows how much daylight passes through a window. A higher number is brighter."
url: https://honeyrock.multisites.ai/glossary/visible-transmittance
publisher: Honey Rock Window and Door
phone: +1-214-484-9982
quote: https://honeyrock.multisites.ai/contact-us
---

# Visible transmittance (VT)

Visible transmittance, or VT, is a number from 0 to 1 that shows how much daylight passes through a window. A higher number is brighter.

VT measures the share of visible light that gets through the whole product, including glass and frame. A high VT means a bright room. A low VT means a darker, tinted look. Gains in energy performance from coatings can come with a lower VT, so the number helps you balance them.

The NFRC lists VT on the window label next to the [U-factor](https://honeyrock.multisites.ai/glossary/u-factor) and [SHGC](https://honeyrock.multisites.ai/glossary/shgc). A [low-E coating](https://honeyrock.multisites.ai/glossary/low-e-coating) with a high VT can block heat and still keep rooms bright. Read our guide to the NFRC label for the full set of ratings, and see SHGC and U-factor for Texas.

[Where it mattersEnergy-efficient windows for Texas](https://honeyrock.multisites.ai/energy-efficient-windows-texas)

## Related terms

-   [SHGC (Solar Heat Gain Coefficient)](https://honeyrock.multisites.ai/glossary/shgc)
-   [U-factor](https://honeyrock.multisites.ai/glossary/u-factor)
-   [Low-E coating](https://honeyrock.multisites.ai/glossary/low-e-coating)
-   [NFRC label](https://honeyrock.multisites.ai/glossary/nfrc-label)

## Sources

1.  [NFRC: National Fenestration Rating Council](https://nfrc.org/)

![A modern home with wide glass doors lit warm at dusk beside a pool](https://honeyrock.multisites.ai/_astro/dusk-modern-home-pool-01.CeePxgPr_Z2giQin.webp)

## Let’s frame your view.

Send your plans or a few photos of the openings. We will help you choose the system, the brand and the glass.

[Start your project](https://honeyrock.multisites.ai/contact-us)[or call (214) 484-9982](tel:+1-214-484-9982)