Roof Rack Sizes: Crossbar Length, Spacing, Height and Weight Limits
Roof racks are sized to the vehicle, not one-size-fits-all. This covers how crossbar length is chosen, how far apart bars go, how much weight a roof can take, and how much height a rack and its load add.
Roof rack crossbars are typically 42-60 in (108-150 cm) long, chosen to match the roof width at the mounting points. Most car and SUV roofs are rated for a dynamic load of about 100-165 lb (45-75 kg) including the rack itself. Bars are usually set 24-36 in (60-90 cm) apart, and a rack with a cargo box adds roughly 18-22 in (46-56 cm) to the vehicle's height.
- Crossbar length
- 42-60 in (108-150 cm)
- Typical roof limit
- 100-165 lb (45-75 kg)
- Bar spread
- 24-36 in (60-90 cm)
- Height with box
- +18-22 in
On this page
Crossbar lengths
Crossbars are sold in fixed lengths and the rack maker's fit guide says which one suits your vehicle. As an example, Thule's WingBar Evo aerodynamic bar comes in five lengths:
| Bar length | Inches | Typical vehicles |
|---|---|---|
| 108 cm | 42.5 in | Small cars and hatchbacks |
| 118 cm | 46.5 in | Compact cars, small crossovers |
| 127 cm | 50.0 in | Midsize sedans, compact SUVs |
| 135 cm | 53.1 in | Midsize SUVs, wagons, minivans |
| 150 cm | 59.1 in | Full-size SUVs, vans, pickups with caps |
Other makers use similar steps of roughly 4 in (10 cm). The usable length between the feet is what limits how many bikes, boats or boxes fit side by side; the overhang outside each foot is useful for a kayak cradle or bike mount on the edge.
Roof types and how racks attach
| Roof type | How to recognize it | How the rack mounts |
|---|---|---|
| Raised side rails | Rails running front to back with a gap underneath | Feet clamp around the rails; bar position is adjustable along the rail |
| Flush rails | Low rails fixed to the roof with no gap | Feet grip the rail's inner edge; vehicle-specific kit |
| Fixed points | Covers or plugs in the roof molding | Feet bolt to threaded points; bar spacing fixed by the car |
| Naked (bare) roof | No rails or points | Clamp feet hook into the door frames with a model-specific kit |
| Factory crossbars | Bars fitted from the factory, sometimes stowable | Accessories mount directly; check the lower bar load rating |
| Rain gutters or tracks | Older vehicles, vans and some trucks | Gutter feet or track-mount feet; spacing very flexible |
How much weight a roof rack can carry
Three limits apply, and the lowest one wins:
- The vehicle's roof load limit, in the owner's manual. Typical dynamic limits are 100-165 lb (45-75 kg) for cars and crossovers. Some SUVs are higher: the 2020-onward Subaru Outback, for instance, is rated for 176 lb (80 kg) dynamic and 700 lb (318 kg) static on its crossbars.
- The rack system's rating, usually printed on the bar or foot packaging, and sometimes reduced for a specific fit kit.
- The accessory's rating, such as a roof box's maximum load.
The rack and accessories count against the limit. With a 165 lb roof rating, a 13 lb set of bars and a 45 lb roof box leave 107 lb (49 kg) for cargo.
Weight on the roof raises the center of gravity, increasing body roll and the risk of rollover in emergency maneuvers. Put dense items inside the vehicle or in a hitch cargo carrier, and keep roof loads light and bulky.
Rooftop tents
Rooftop tents typically weigh 100-200 lb (45-90 kg). The tent's weight must be within the dynamic limit, because it is carried while driving. Once parked, the occupants' weight is carried as static load, which most roofs and racks handle at several times the dynamic figure. Check both the vehicle and rack ratings for static load before buying, since not every manufacturer publishes one.
Crossbar spacing
- Fixed-point roofs set the spread for you, typically 24-32 in (60-80 cm).
- Roof boxes usually need a minimum spread of about 24 in (60 cm) and list a maximum too. The box's mounting rails or clamps define the range.
- Kayaks, canoes and SUP boards are more stable with a wider spread, 28-36 in (70-90 cm) or more, and need bow and stern lines on long boats.
- The front bar should sit far enough back that a roof box lid or bike clears the open tailgate or hatch at the rear, and nothing overhangs the windshield.
How much height a roof rack adds
| Setup | Added height |
|---|---|
| Crossbars on flush rails or fixed points | 3-4 in (8-10 cm) |
| Crossbars on raised rails | 4-6 in (10-15 cm) |
| Bars plus roof box | 18-22 in (46-56 cm) |
| Bars plus kayak in J-cradle | about 20-30 in (50-76 cm) |
| Bars plus upright bike | about 42-48 in (107-122 cm) |
| Rooftop tent, closed | about 12-18 in (30-46 cm) plus bars |
Add these to your vehicle's height (see the car dimensions guide) before entering a garage, carport, drive-through or parking structure. A 67 in crossover with a roof box stands about 85-89 in tall, over the 84 in (7 ft) of a standard garage door. Parking garages commonly post clearances of 6 ft 6 in to 7 ft (1.98-2.13 m).
How much fits on the bars
Width between the feet is the budget. On a 50 in (127 cm) bar, plan roughly:
- Bikes (upright mounts): two to three, with the handlebars staggered. Four needs bars of 53-59 in on a wide roof.
- Kayaks: two on their sides in J-cradles, or one lying flat. Recreational kayaks are 24-34 in (61-86 cm) wide; see the kayak size guide.
- Skis and snowboards: carriers hold 4 or 6 pairs of skis, or 2-4 boards. Ski lengths are in the ski size chart.
- Roof box plus bike: a narrow box of about 30-34 in leaves room for one bike on wide bars.
Measuring for a roof rack
- Identify the roof type from the table above.
- Note the exact year, model and body style. A sedan and wagon of the same model use different kits.
- Measure the roof width at the front and rear mounting positions; roofs taper toward the back, so the rear bar sometimes needs a shorter length.
- Measure the existing rail spread if you have side rails: the distance between rail centers at each mounting point.
- Check the manual's roof load limit and any notes on where loads must be placed.
For roof boxes and bags in detail, including volumes and lengths, see the cargo carrier size guide. Tent sizes for camping trips are in the camping tent size guide.
Frequently asked questions
Do roof racks come in different sizes for different cars?
Yes. The feet (towers) and fit kit are specific to the roof type and often to the exact model, and crossbars come in several lengths. Rack makers' fit guides list the correct foot, kit and bar length by year, make, model and body style.
Is there a limit to how long roof rack crossbars can be?
There is no single legal limit for passenger cars, but rack makers specify a bar length for each vehicle, usually leaving 1-4 in (3-10 cm) of overhang beyond each foot. Bars that stick out past the body or mirrors catch on doors, people and garage frames and add wind noise, so choose the shortest length that carries your gear.
What is the difference between dynamic and static roof load?
Dynamic load is what the roof can carry while driving, with braking and cornering forces. It is the figure in the owner's manual, typically 100-165 lb (45-75 kg). Static load, for a parked vehicle, is several times higher and matters for rooftop tents with people inside; not all manufacturers publish it.
How far apart should roof rack crossbars be?
Follow the vehicle fit guide; on many cars the feet must go at marked points. For accessories, most roof boxes need at least about 24 in (60 cm) between bars, and kayaks and long boards are more stable with 28-36 in (70-90 cm).
Does a roof rack affect fuel economy?
Yes. US Department of Energy figures (fueleconomy.gov) estimate that a large, blunt roof-top cargo box cuts fuel economy by about 2-8% in city driving, 6-17% on the highway and 10-25% at 65-75 mph. Empty bars also add drag, so remove them when not in use.