Heel-to-toe drop (also called "drop" or "offset") is the difference in height between the heel and forefoot of a shoe, measured in millimeters. A shoe with 25mm of cushion at the heel and 15mm at the forefoot has a 10mm drop. A zero drop shoe has the same height at both ends — your heel and forefoot sit on a level platform.
Why Drop Matters
Drop changes how your foot strikes the ground. Conventional running shoes typically have 10-12mm of drop, which tilts your foot forward and encourages heel striking. Zero drop shoes place your foot in a neutral position, closer to how you'd stand barefoot.
This difference affects the entire chain of movement from your feet up through your ankles, knees, hips, and spine. A level platform allows your body to use its natural shock absorption — the arch of the foot, the Achilles tendon, and the calf muscles — rather than relying on shoe cushioning alone.
Common Drop Ranges
- 0mm (zero drop) — Level heel-to-toe. Brands like Altra, Xero Shoes, and Vivobarefoot specialize in this. Promotes natural foot mechanics and midfoot or forefoot striking.
- 4-6mm (low drop) — A compromise between conventional and zero drop. Some runners find this easier to transition to than going straight to zero. Brands like Topo Athletic and Inov-8 offer options here.
- 8-12mm (standard drop) — Most conventional running shoes fall in this range. Encourages heel striking and relies on cushioning to absorb impact.
Drop vs Stack Height
Drop and stack height are different measurements that people often confuse. Drop is the difference between heel and forefoot height. Stack height is the total amount of material between your foot and the ground.
A shoe can be zero drop with high stack height (like the Altra Olympus with 33mm of cushion) or zero drop with minimal stack height (like the Xero HFS with 5.5mm). Both are level, but the ground feel is completely different.
How Drop Affects Running Form
High drop (8-12mm) tends to encourage landing on your heel first. The elevated heel catches the ground before the forefoot, creating a braking force with each step. The shoe's cushioning absorbs the impact rather than your body's natural mechanisms.
Zero drop (0mm) encourages a midfoot or forefoot landing. Without an elevated heel, your foot naturally lands under your center of gravity rather than reaching out ahead. This typically results in shorter strides, higher cadence, and less braking force per step.
Neither pattern is inherently right or wrong. But if you want to run with a more natural gait, zero drop removes the shoe from the equation and lets your body find its preferred movement pattern.
Transitioning from High Drop to Zero Drop
The most common mistake is switching too fast. Your calves, Achilles tendons, and foot muscles need time to adapt to the increased workload that comes with a lower drop.
A safe approach:
- Start with zero drop shoes for short walks and daily wear
- After 2-3 weeks, try short runs (1-2 miles) in zero drop shoes
- Alternate between your old shoes and zero drop shoes for 4-6 weeks
- Gradually increase the proportion of miles in zero drop shoes
- Listen to calf tightness and Achilles soreness — both are signals to slow down
See the Transition Guide for a detailed week-by-week plan.
Does Zero Drop Prevent Injuries?
Zero drop shoes don't automatically prevent injuries, but they change which structures bear the load. High-drop shoes shift stress toward the knees and hips. Zero drop shoes shift stress toward the calves, Achilles, and plantar fascia.
The research suggests that the best drop for you depends on your body, your running form, and your injury history. What zero drop does reliably is allow your foot to function more naturally, which many runners find reduces chronic issues over time.