Measure the height, measure the space in front of it, and tell us about your pet’s joints. We will tell you whether a ramp or steps are safer, what angle is safe, and how much load the thing has to carry.
Safe ramp angle and step size by condition
These are the limits this calculator uses. The angle given is a maximum, never a target — a shallower ramp always loads the joints less. Shorter steps are safer than tall ones, and deeper tread is safer than shallow.
| Condition | Max ramp angle | Max step rise | Min step depth | Weight factor |
|---|---|---|---|---|
| Dogs | ||||
| Healthy adult | 25° | 18 cm | 28 cm | 2.0× |
| Mild stiffness or arthritis | 20° | 15 cm | 30 cm | 2.0× |
| Advanced arthritis or hip dysplasia | 15° | 12 cm | 32 cm | 2.2× |
| Post-surgery or IVDD recovery | 12° | 10 cm | 34 cm | 2.5× |
| Cats | ||||
| Healthy adult | 30° | 20 cm | 18 cm | 2.0× |
| Senior or arthritic | 22° | 14 cm | 22 cm | 2.0× |
Weight factor is the multiple of your pet’s body weight the ramp or step has to carry. It rises with the condition because a pet that cannot control its descent puts far more load through the surface than it does standing still.
How much floor run a ramp needs
Floor run is the horizontal distance a ramp eats up. Find your angle across the top, then read down to the height you need to climb. If your available space is shorter than that number, a ramp is the wrong answer — steps are.
| Height to climb | 30° | 25° | 22° | 20° | 15° | 12° |
|---|---|---|---|---|---|---|
| 15 cm | 26 cm | 33 cm | 38 cm | 42 cm | 56 cm | 71 cm |
| 20 cm | 35 cm | 43 cm | 50 cm | 55 cm | 75 cm | 95 cm |
| 30 cm | 52 cm | 65 cm | 75 cm | 83 cm | 112 cm | 142 cm |
| 40 cm | 70 cm | 86 cm | 100 cm | 110 cm | 150 cm | 189 cm |
| 50 cm | 87 cm | 108 cm | 124 cm | 138 cm | 187 cm | 236 cm |
| 60 cm | 104 cm | 129 cm | 149 cm | 165 cm | 224 cm | 283 cm |
Required floor run = height ÷ tan(angle). Ramp surface length = height ÷ sin(angle). That and the table above are the whole calculation — there is nothing hidden inside the tool.
Why angle is the whole question
A ramp that is too steep is worse than no ramp at all — it loads the same joints you were trying to protect, with less grip. The safe angle depends on the animal, not on the furniture, which is why a healthy two-year-old and a dog recovering from surgery get different answers here.
How this is calculated
- Maximum safe angle — set per condition, from 25° for a healthy dog down to 12° for post-surgery recovery.
- Required floor run — the height divided by the tangent of that angle. This is the number that decides whether a ramp fits your room.
- Ramp surface length — the height divided by the sine of the angle, so you buy the right length and not a guess.
- Step elevation and depth — per condition, so the alternative is also built to a standard rather than improvised.
This is not veterinary advice
Joint conditions vary enormously, and a vet who has examined your pet will always beat a calculator. Use these numbers to shop with, and confirm the target angle with your vet before you buy — particularly for anything recovering from surgery or living with a neurological condition.