How to level a motorhome or caravan with your phone
Short answer: lay your phone flat on the floor of the vehicle with its top edge pointing forward, read the front-to-back tilt and the side-to-side tilt, then work out the height each wheel needs with distance × sine of the angle. Raise the low wheels with ramps or blocks until the highest wheel is the only one that stays on the ground.
Why level a motorhome or caravan
- Comfort: a sloping bed is tiring, and a ball rolls away on the table.
- Fridge: absorption fridges work properly only within a limited tilt.
- Water: sinks and shower trays drain better on a level vehicle.
- Stability: a level caravan is easier to steady with its corner supports.
What you need
- A phone with a calibrated level app. See how to calibrate your phone as a spirit level.
- Levelling ramps or blocks that are rated for your vehicle's weight.
- Wheel chocks.
- A tape measure for the wheelbase (front-to-rear wheel distance) and the track width (distance between left and right wheels).
Step by step
- Park on the best spot you can find and put the handbrake on.
- Lay the phone flat on the floor, screen up, with its top edge pointing to the front of the vehicle.
- Read both tilts: how much the front is higher or lower than the rear, and how much the right side is higher or lower than the left.
- Work out the raise for each wheel (see below).
- Place the ramps or blocks in front of or behind the wheels that need lifting, and drive or reverse slowly onto them.
- Check again. Re-read the phone, adjust, then chock the wheels and apply the handbrake before you settle in.
The formula
The height a wheel must be raised is its distance from the highest wheel multiplied by the sine of the tilt angle in that direction:
- front-to-back: wheelbase × sin(front-to-back tilt)
- side-to-side: track width × sin(side-to-side tilt)
The highest wheel stays at zero, and every other wheel is raised to meet it. For tilts of a few degrees, the sine and the tangent are almost the same, so a calculator on your phone is enough.
A worked example
A motorhome has a 3.6 m wheelbase and a 1.9 m track width. The phone shows the front is 1.5° higher than the rear and the right side is 1.0° higher than the left. The highest wheel is the front right.
| Wheel | Calculation | Raise |
|---|---|---|
| Front right | highest wheel | 0 |
| Front left | 1.9 m × sin 1.0° | 33 mm (1.3 in) |
| Rear right | 3.6 m × sin 1.5° | 94 mm (3.7 in) |
| Rear left | 94 mm + 33 mm | 127 mm (5.0 in) |
Caravans
A caravan usually has two wheels on one axle and a hitch jack or jockey wheel at the front. Level it side to side by raising the low wheel with a ramp or block, using the axle track width in the formula. Level it front to back by winding the hitch jack up or down, using the distance from the axle to the hitch. Always chock the wheels before you unhitch.
Safety
- Use ramps or blocks rated for the full weight of your vehicle, and place them on firm, flat ground.
- Never work under a vehicle that is held up only by a jack or a stack of blocks.
- Drive onto the ramps slowly and stop when you are level. Do not overshoot.
Measure the tilt with Engineer Tools
Engineer Tools shows a circular level and a horizontal and a vertical vial together, each with its own reading, so one placement of the phone gives you the front-to-back and the side-to-side tilt. Calibrate it first with a two-point flip, read both tilts in degrees, and use the formula above for each wheel. Read more about Engineer Tools, which is coming soon to Google Play.
Frequently asked questions
How do I work out how high to raise each wheel?
Multiply the distance between two wheels by the sine of the tilt angle between them. For example, 3.6 m between the front and rear wheels at 1.5 degrees means about 94 mm (3.7 in).
How level does a motorhome or caravan need to be?
Level enough to sleep comfortably, for water to drain and for the fridge to work. Many absorption fridges allow only a few degrees of tilt, often around 3, so check your fridge manual.
Can I use Engineer Tools for this?
Yes, to measure the tilt. Its bubble level shows a circular level and a horizontal and a vertical vial together, each with its own reading, so with the phone laid flat you read both tilts at once. You then work out each wheel's raise with the formula in this guide. Engineer Tools is coming soon to Google Play.
More guides
- Slope conversion: degrees to percent, mm per metre and inches per foot
Convert an angle in degrees to percent slope, millimetres per metre, inches per foot and a 1:n ratio, with formulas and ready-made tables for common slopes.
- How to use your phone as a spirit (bubble) level and calibrate it
How a phone bubble level works, how to place it, and how to calibrate it with a two-point flip so the reading is accurate on any surface.