Take a load off: The Ro Knee Relief Calculator
Every pound you lose is 4 pounds each knee stops carrying with every step. See how much weight loss could take a load off each knee.
Knee Relief Calculator
Losing takes about off each knee with every step.
Move the slider to see what comes off your knees.
Off each knee, per step
Off each knee, per mile
That’s per mile walked. Federal limits cap them at 80,000 lbs on US interstates.
The load-bearing details
Walking isn’t the same as standing on one leg at a time. Your quads and hamstrings clamp the knee to keep you upright, so the joint takes a multiple of your body weight with every step. When researchers ran people with knee arthritis through 3D gait analysis before and after a weight-loss trial, each pound lost showed up as roughly 4 pounds less compressive force.
- Multipliers: 4× per step and 4,800× per mile, from Messier et al., Arthritis & Rheumatism, 2005. The per-mile figure assumes 1,200 strides, as the authors did.
- The 4:1 ratio was measured in older adults with knee osteoarthritis who lost modest weight through diet and exercise. Extending it to 50 or 100 lbs is our extrapolation, not theirs.
- It’s compressive load during level walking. Stairs, hills, running and carrying groceries all multiply differently.
- Less load isn’t the same as less damage. Weight loss reliably lowers knee pain and improves function, and long-term MRI studies link it to slower cartilage wear, but no randomized trial has yet shown it slows osteoarthritis progression.
Sources
- Messier et al., Arthritis & Rheumatism, 2005. Weight loss reduces knee-joint loads in knee osteoarthritis.
- Messier et al., JAMA, 2013. The IDEA trial: diet and exercise in knee osteoarthritis.
- Gersing et al., Radiology, 2017. Weight loss and knee cartilage changes on MRI over 48 months.
- Gersing et al., Osteoarthritis and Cartilage, 2019. Weight loss and cartilage degeneration over 96 months.
A physics estimate for curiosity, not medical advice.