Garage door spring size calculator
Measure the coils and get the exact DASMA wire size, color code, and a copy-ready order string, for both torsion and extension springs. Instant, and no signup.
Red winding cone = left-wound (mounts right of center); black = right-wound. Send what you have. The result flags anything still needed.
How to measure torsion spring wire size (the 10 & 20 coil method)
Calipers are unreliable on a rusty, installed spring, so the field-standard trick is to measure a run of coils and divide:
- With the spring unwound and safe, push 20 coils tightly together.
- Measure that length in inches and divide by 20; that's your wire diameter.
- Repeat with 10 coils ÷ 10 as a cross-check. Both numbers should match. If they differ by more than 0.010", recount and remeasure.
- Enter both above, and the calculator snaps to the nearest DASMA standard and gives the color code.
Some sizes are so close (for example .2950 White vs .2970 Red) that no tape measure can tell them apart. When that happens the tool tells you to read the painted DASMA color instead of guessing.
Left-hand vs right-hand wind
A torsion order needs the wind direction. Viewed from inside the garage facing the door on a standard center-mounted setup:
- Left-wound (LH): RED winding cone, mounts to the right of the center bearing.
- Right-wound (RH): BLACK winding cone, mounts to the left of the center bearing.
The red/black winding-cone color is separate from the DASMA wire-size color; don't confuse the two.
DASMA torsion spring color code chart
Standard oil-tempered / hard-drawn wire sizes and their DASMA colors (Technical Data Sheet #171):
| Wire size (in) | DASMA color |
|---|---|
.1200 | Orange |
.1250 | Light Blue |
.1350 | Yellow |
.1390 | White |
.1430 | Red |
.1480 | Brown |
.1562 | Tan |
.1620 | Green |
.1770 | Gold |
.1820 | Purple |
.1875 | Blue |
.1920 | Orange |
.2000 | Light Blue |
.2070 | Yellow |
.2187 | White |
.2253 | Red |
.2340 | Brown |
.2375 | Tan |
.2437 | Green |
.2500 | Gold |
.2570 | Purple |
.2625 | Blue |
.2730 | Orange |
.2830 | Light Blue |
.2890 | Yellow |
.2950 | White |
.2970 | Red |
.3065 | Brown |
.3125 | Tan |
.3195 | Green |
.3310 | Gold |
.3437 | Blue |
.3625 | Orange |
.3750 | Light Blue |
.3938 | Yellow |
.4062 | White |
.4218 | Red |
.4305 | Brown |
.4375 | Tan |
.4531 | Green |
.4615 | Gold |
.4687 | Blue |
.4844 | Orange |
.4900 | Light Blue |
.5000 | Yellow |
.5312 | White |
.5625 | Red |
.5938 | Purple |
.6250 | Brown |
Extension spring color code by door weight
Extension springs are rated by the weight they lift. Colors repeat every 100 lb, so always confirm against the actual door weight, and remember you need two.
| Door weight | DASMA color |
|---|---|
50 lb (23 kg) | Red |
60 lb (27 kg) | Brown |
70 lb (32 kg) | Orange |
80 lb (36 kg) | Gold |
90 lb (41 kg) | Light Blue |
100 lb (45 kg) | Tan |
110 lb (50 kg) | White |
120 lb (54 kg) | Green |
130 lb (59 kg) | Yellow |
140 lb (64 kg) | Blue |
150 lb (68 kg) | Red |
160 lb (73 kg) | Brown |
170 lb (77 kg) | Orange |
180 lb (82 kg) | Gold |
190 lb (86 kg) | Light Blue |
200 lb (91 kg) | Tan |
210 lb (95 kg) | White |
220 lb (100 kg) | Green |
230 lb (104 kg) | Yellow |
240 lb (109 kg) | Blue |
250 lb (113 kg) | Red |
260 lb (118 kg) | Brown |
270 lb (122 kg) | Orange |
280 lb (127 kg) | Gold |
290 lb (132 kg) | Light Blue |
300 lb (136 kg) | Tan |
Want the full walkthrough, not just the tool? Read the field guide: How to measure a garage door torsion spring (without guessing)
Frequently asked questions
How do I measure garage door torsion spring wire size?
Push 20 coils tightly together, measure that length in inches, and divide by 20 (or measure 10 coils and divide by 10). That number is the wire diameter. This calculator snaps it to the nearest DASMA standard size and gives you the color code. Measuring both 10 and 20 coils cross-checks for error.
What is the 10 and 20 coil method?
Calipers are unreliable on a rusty installed spring, so techs measure the length of 10 coils and 20 coils and divide by the count. Both should give the same wire size; if they disagree by more than 0.010", recount and remeasure.
Does the DASMA color tell me everything?
No. The painted color only encodes wire size, not inside diameter, length, or wind direction, and colors repeat every so often. Always confirm wire size, ID, length, and wind by measurement before ordering.
How do I tell left-hand from right-hand wind?
On a standard center-mounted setup viewed from inside the garage: a left-wound spring has a RED winding cone and mounts to the right of center; a right-wound spring has a BLACK winding cone and mounts to the left. The winding-cone color is separate from the DASMA wire-size color.
How do I pick an extension spring?
Extension springs are chosen by door weight, not coil measurement, and you need two (one per side). Weigh the door, then match it to the DASMA weight/color chart. This tool does that too: switch to the Extension tab.
Audrey does this in the truck, hands-free.
This calculator runs the exact logic built into Ask Audrey, where your techs just ask out loud and get the answer cited to your own manuals (plus flash codes, remote compatibility, and part numbers). Every tech, a senior tech.