Garage Door Spring Size Calculator
Convert garage door dimensions and weight to the correct torsion or extension spring specifications.
Covers standard and custom door sizes.
Select your garage door size and material to see spring and opener specifications.
Understanding Garage Door Spring Sizing
Garage door springs counterbalance the weight of the door, making it possible to open manually or with a small electric opener. Without properly sized springs, the door would be too heavy to lift. There are two spring systems: torsion springs (mounted above the door on a shaft) and extension springs (mounted on each side along the horizontal tracks). Torsion springs are preferred for their smoother operation, longer life, and safer failure mode.
Door Weight by Size and Material:
| Door Size | Steel (Insulated) | Steel (Non-Insulated) | Wood | Aluminum |
|---|---|---|---|---|
| 8 x 7 ft (2.4 x 2.1 m) | 130 lb (59 kg) | 85 lb (39 kg) | 150 lb (68 kg) | 70 lb (32 kg) |
| 9 x 7 ft (2.7 x 2.1 m) | 155 lb (70 kg) | 100 lb (45 kg) | 175 lb (79 kg) | 85 lb (39 kg) |
| 16 x 7 ft (4.9 x 2.1 m) | 250 lb (113 kg) | 160 lb (73 kg) | 300 lb (136 kg) | 130 lb (59 kg) |
| 16 x 8 ft (4.9 x 2.4 m) | 290 lb (132 kg) | 185 lb (84 kg) | 350 lb (159 kg) | 150 lb (68 kg) |
| 18 x 7 ft (5.5 x 2.1 m) | 280 lb (127 kg) | 180 lb (82 kg) | 340 lb (154 kg) | 145 lb (66 kg) |
| 18 x 8 ft (5.5 x 2.4 m) | 320 lb (145 kg) | 210 lb (95 kg) | 400 lb (181 kg) | 170 lb (77 kg) |
Torsion Spring Specifications:
Torsion springs are defined by three measurements: wire diameter, inside coil diameter, and length. The spring must store enough energy (measured in inch-pounds) to lift the door through its full travel. The energy requirement is calculated as:
Spring Energy = Door Weight x Door Height x 0.5
Common torsion spring wire diameters range from 0.207 inches (5.3 mm) for light single-car doors to 0.295 inches (7.5 mm) for heavy double-car doors. The inside coil diameter is typically 1.75 inches (44 mm) or 2 inches (51 mm) for residential applications.
Spring Cycle Life:
Springs are rated by cycle life, where one cycle equals one full open-and-close operation. Standard springs are rated for 10,000 cycles, which lasts approximately 7 to 10 years with average use (3 to 4 cycles per day). High-cycle springs rated for 25,000 to 50,000 cycles cost more initially but last 2 to 5 times longer, making them a better value for busy households.
| Cycle Rating | Approximate Years | Best For |
|---|---|---|
| 10,000 cycles | 7 - 10 years | Standard residential |
| 15,000 cycles | 10 - 14 years | Active households |
| 25,000 cycles | 17 - 23 years | Very active, multiple cars |
| 50,000 cycles | 35+ years | Commercial, frequent use |
Opener Motor Size:
The garage door opener motor must be powerful enough to lift and lower the door smoothly. Since the springs do most of the lifting, the opener mainly needs to overcome friction and provide controlled movement.
- 1/3 HP (0.25 kW): Single-car uninsulated steel or aluminum doors up to 150 lb (68 kg)
- 1/2 HP (0.37 kW): Standard single-car insulated doors up to 200 lb (91 kg)
- 3/4 HP (0.56 kW): Double-car doors and heavier single-car doors up to 300 lb (136 kg)
- 1 HP (0.75 kW): Heavy custom wood doors and oversized doors up to 400 lb (181 kg)
- 1-1/4 HP (0.93 kW): Commercial and extra-heavy doors over 400 lb (181 kg)
Safety Warning:
Garage door springs store tremendous energy and can cause serious injury or death if they break or are improperly handled. Torsion spring replacement should be performed by a trained technician with proper tools. A spring for a 200-pound door stores approximately 14,000 inch-pounds of energy. Never attempt to adjust or replace torsion springs without professional training and the correct winding bars.