Tools
R-value / U-factor Converter
A free tool that converts between R-value and U-factor and checks an energy-code target.
R-value / U-factor converter
R-16 equals a U-factor of about 0.063.
R-value and U-factor are inverses, but a door's center-of-section R-value is not the same as the whole-assembly U-factor energy codes regulate. Check the door's rated U-factor against your local code.
In plain terms
R-value and U-factor measure the same door from opposite ends. R-value is how well the door resists heat flow, so higher is better. U-factor is how much heat gets through, so lower is better. They are exact opposites: one is one divided by the other.
Rule of thumb: U-factor is one divided by the R-value. R-16 equals a U-factor of about 0.06. To go the other way, divide one by the U-factor.
What each part means
| Term | Plain meaning | Better when |
|---|---|---|
| R-value | Resistance to heat flow | higher |
| U-factor | Heat that passes through | lower |
| Center vs whole | Center-of-section R vs whole-door U | codes regulate the whole-door U-factor |
A worked example
Worked example. A door advertised at R-16 in the center of the section converts to a U-factor of about 0.06 at that spot. Energy code looks at the whole-door U-factor, which is higher, so always check the door's rated U-factor, not just the center R-value.
Related questions
Questions this tool answers
Short answers below, with a link to the full write-up on each.
Does Colorado energy code require an insulated garage door on an attached garage?
Yes.
Read full answerWhat U-factor does a garage door need to meet the 2021 energy code?
The 2021 IECC Section R402.2.12 sets a maximum U-factor of 0.45 for garage doors in attached conditioned garages.
Read full answerIs the Northwest Door Therma Tech 3500 an insulated garage door, and what is its R-value?
Yes, the Northwest Door Therma Tech 3500 is fully insulated.
Read full answerWhat R-value should my garage door have in Colorado?
Most Colorado Front Range homes (IECC Climate Zone 5) benefit from a garage door rated R-10 to R-16.
Read full answerWhat is the difference between R-value and U-factor for garage doors?
R-value measures thermal resistance (higher is better).
Read full answerReference & standards
The codes and standards behind it
The engineering sources this tool is built on.
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