What gain setting should I start at?
Gain controls how much current your tow vehicle sends to the trailer’s electric brakes. The target is for the trailer to pull itself straight slightly ahead of the truck, so it never pushes you during a stop. The right number depends on loaded trailer weight, controller type and road surface, which is why the chart below gives a starting point rather than an answer.
Then test it — with the trailer loaded. A calibration done on an empty trailer is wrong the moment you hitch up for a real trip.
Trailer Configuration
Medium Gain Setting (4-6)
Medium trailer — start at the recommended gain. At 25 mph, manually actuate the trailer brakes alone. The trailer should slow the tow vehicle noticeably without locking up. Adjust up or down by 0.5 increments.
⚠️ How to Test Your Gain Setting
- Find an empty parking lot or quiet street
- Drive at 25 mph
- Manually slide the brake controller lever to apply trailer brakes only
- The trailer brakes should grab firmly without locking up
- If wheels lock: reduce gain by 0.5. If too weak: increase by 0.5
- Repeat until you find the sweet spot
What Is Trailer Brake Gain?
Brake gain controls how much electrical current flows from your tow vehicle to the trailer's electric brakes. A higher gain means stronger braking force from the trailer. The goal is to set the gain so the trailer brakes engage slightly ahead of your truck's brakes, keeping the rig straight and preventing the trailer from pushing the truck during stops.
Proportional controllers automatically vary brake force based on how hard you're braking. Time-delayed controllers apply a fixed amount of power after a delay. Each requires a slightly different gain calibration.
How to Properly Set Your Brake Gain
Setting brake gain is not a one-time task. Your ideal gain changes with trailer weight, loading distribution, road conditions, and even weather. Follow this systematic approach every time you hitch a different trailer or significantly change your load.
- Start low. Set your brake controller to gain 3 or 4 — never start at maximum gain or you risk locking up the trailer wheels immediately.
- Find a safe test area. An empty parking lot, industrial road, or quiet residential street with no traffic. Dry pavement only — wet or gravel surfaces will give false readings.
- Accelerate to 25 mph. Maintain a steady speed. Do not test at highway speeds until your gain is dialed in at low speed first.
- Manually actuate trailer brakes only. Use the manual override slider or lever on your brake controller. Do not press your truck's brake pedal — this tests only the trailer brakes in isolation.
- Observe the result. The trailer brakes should grab firmly and slow the rig noticeably. If the trailer wheels lock up and slide, your gain is too high. If you feel little to no braking effect, your gain is too low.
- Adjust in 0.5 increments. Increase or decrease the gain by 0.5 and repeat. The ideal setting is where the trailer brakes engage firmly without locking up.
- Test at highway speed. Once dialed in at 25 mph, test at 45-55 mph on an empty road. You may need to reduce gain slightly at higher speeds.
Proportional vs. Time-Delayed Controllers
Understanding your brake controller type is essential because the gain behaves differently on each system:
Proportional (Inertia-Based)
Uses an internal accelerometer to detect how quickly you're stopping and applies proportional power to the trailer brakes. The harder you stop, the more trailer brake force is applied. These controllers provide smoother, more natural braking and require less frequent gain adjustment. Examples: Tekonsha P3, Prodigy, Curt Spectrum.
Time-Delayed (Timed)
Applies a fixed amount of brake power after a user-set time delay. These are simpler and cheaper but require more frequent gain adjustment because they don't adapt to stopping force. The gain setting directly controls how much power is delivered, making calibration more critical. Examples: Reese Towpower, Hopkins.
Common Brake Gain Mistakes
- Setting gain too high. Causes trailer wheels to lock up, leading to flat spots on tires, loss of control, and potential jackknifing. Always err on the low side and increase gradually.
- Never recalibrating for different loads. The gain that works for a 4,000 lbs utility trailer will be dangerously wrong for an 8,000 lbs travel trailer. Always recalibrate when your load changes by more than 20%.
- Testing only on dry pavement. Your gain setting may need adjustment in rain, snow, or gravel. If you encounter brake lockup in wet conditions, reduce gain by 1-2 points and test again.
- Ignoring the manual override test. Many drivers only test brakes by pressing the truck brake pedal. This doesn't isolate the trailer brakes. Always use the manual override lever to test trailer brakes independently.
- Forgetting about brake sync. Even with correct gain, your trailer brakes should activate slightly before your truck's brakes. Most proportional controllers sync automatically. Timed controllers need the delay setting adjusted.
When to Recalibrate Your Brake Gain
Brake gain is not a set-and-forget setting. Recalibrate whenever any of these conditions change:
- You hitch a different trailer
- Your trailer load changes by more than 1,000 lbs
- You switch between a loaded and empty trailer
- Driving conditions change significantly (highway vs. city, dry vs. wet)
- You install a new brake controller
- Your trailer brakes have been serviced or replaced
- At the start of each towing season after winter storage
Trailer brake gain chart by trailer weight
Starting points only — the same model the calculator above uses, tabulated. Electric drum brakes vary with magnet wear, drum condition, wiring voltage drop, and tire grip, so two identical trailers can want a full point of difference. Always finish with the road test.
| Loaded trailer weight | 1 axle, proportional | 2 axles, proportional | 2 axles, time-delayed | 3 axles, time-delayed |
|---|---|---|---|---|
| Up to 3,000 lbSmall utility, single-axle boat, teardrop | 3.0 | 3.0 | 3.0 | 4.0 |
| 3,001 - 6,000 lbMid-size travel trailer, car hauler | 3.0 | 4.0 | 5.0 | 6.0 |
| 6,001 - 10,000 lbLarge travel trailer, enclosed cargo | 5.0 | 6.0 | 7.0 | 8.0 |
| Over 10,000 lbFifth wheel, toy hauler, equipment trailer | 7.0 | 8.0 | 9.0 | 10.0 |
Reading the chart: heavier trailers need more current, more axles spread the same stopping job over more magnets, and a time-delayed controller needs roughly one extra point because its output does not scale with how hard you are stopping. If your figure lands more than two points away from the chart, look at the brakes before the controller.
Trailer brake gain FAQ
What should I set my trailer brake gain to?
On a two-axle trailer, start near 3 under 3,000 lb, 4-5 at 6,000 lb, 6-7 at 10,000 lb, and 8-9 above that — the lower number for a proportional controller, the higher one for time-delayed. Then confirm with a 25 mph manual-override test. The starting number is only a starting number: brake condition, magnet wear, tire grip, and load distribution all move it.
Is a gain of 10 too high?
Usually, yes. Gain 10 is the top of the range and is normally only appropriate for a heavy multi-axle trailer with worn or weak brakes. If you need 10 on a mid-size trailer to feel any braking, the trailer's brakes, magnets, wiring, or ground connection need service rather than more current.
How do I know if my trailer brake gain is too high?
The trailer wheels lock and skid during the manual-override test, you hear chirping from the trailer tires on light stops, or the rig feels like it is being pulled backwards when you brake. Reduce gain in 0.5 steps until the trailer slows the rig firmly without skidding.
What happens if the gain is too low?
The trailer pushes the tow vehicle during braking. You will notice longer stopping distances, a nose-down feeling under braking, and heat and wear on the tow vehicle's brakes. On a long descent, too little trailer braking is how tow-vehicle brakes fade.
Does gain need to change between an empty and a loaded trailer?
Yes. A gain calibrated with the trailer empty will lock the wheels once it is loaded, and a gain set when loaded will feel weak when empty. Recalibrate whenever the load changes by roughly 1,000 lb or more.
Is the gain setting the same on proportional and time-delayed controllers?
No. A time-delayed controller sends a fixed output, so it typically needs about one point more gain than a proportional controller on the same trailer, plus a delay setting. A proportional controller varies output with how hard you are stopping, so it can run slightly lower.