About the Treadmill Incline Calculator
Raising the incline is the simplest way to make a treadmill workout harder without going faster. A few percent of grade turns an easy walk into a real workout, and steep incline walking has become popular as a low-impact alternative to running. But how much harder is it? This calculator puts a number on it by translating your incline workout into the speed you would need on flat ground to work as hard.
Enter your weight, your treadmill speed and incline, and the time. Using the American College of Sports Medicine walking and running equations, the calculator works out the oxygen cost of the workout, the flat-ground speed with the same cost, the calories burned, how many more that is than walking or running at the same speed with no incline, and how much height you climbed.
How to Use the Treadmill Incline Calculator
Enter your body weight in kg or lb.
Enter the treadmill speed in km/h or mph and the incline in percent.
Enter the time in minutes.
The Formulas
walking (up to 6.4 km/h): VO₂ = 0.1v + 1.8v × grade + 3.5
running (faster): VO₂ = 0.2v + 0.9v × grade + 3.5
v in metres per minute, grade as a fraction, VO₂ in ml/kg/min
flat equivalent: the speed whose VO₂ at 0% equals your VO₂
calories per minute = VO₂ × kg ÷ 1,000 × 5Step-by-Step Example
A 70 kg person walking at 5 km/h on a 10% incline for 30 minutes.
speed 5 km/h = 83.3 m/min (walking equation)
VO₂ 0.1 × 83.3 + 1.8 × 83.3 × 0.10 + 3.5 = 26.8 ml/kg/min
flat 0.1 × 83.3 + 3.5 = 11.8 → 127% more at 10%
equivalent (26.8 − 3.5) ÷ 0.2 = 116.7 m/min = 7 km/h running
calories 26.8 × 70 ÷ 1,000 × 5 × 30 ≈ 282 kcal (158 more than at 0%)
climb 2.5 km × 10% = 250 mHow the Equations Work
Each equation has a horizontal term for moving forward, a vertical term for lifting your body up the slope, and 3.5 for resting. The vertical term for walking, 1.8 × speed × grade, is large: at 10% it is nearly twice the horizontal term. For running, the vertical coefficient is half that, 0.9, because runners move in a way that already includes some vertical work. The calculator uses the walking equation at speeds up to about 6.4 km/h (4 mph) and the running equation above that.
The Flat Equivalent
The flat equivalent answers the question people often ask: "What does this incline equal on flat ground?" It finds the speed with the same oxygen cost at 0%. If that speed would be faster than a normal walk, it is given as a running speed. Steep incline walking often matches easy jogging in effort, which explains why a brisk incline walk can raise heart rate as much as a run.
Popular Incline Workouts
The "12-3-30" workout, walking at 12% incline and 3 mph for 30 minutes, became popular on social media. For a 70 kg person it costs about 29 ml/kg/min, a little over 8 METs, burning roughly 300 calories, similar to jogging around 7.5 km/h on the flat. Enter your own weight to see your figure. Build up to steep inclines gradually, as they load the calves and Achilles tendons heavily.
Handrails and Form
The equations assume you walk freely without holding on. Gripping the rails, especially leaning back on them, takes much of your weight and lets the belt do the work, cancelling much of the incline's effect. Stand tall, swing your arms and take natural steps. If you need the rails to stay on, reduce the incline or speed.
Accuracy
The ACSM equations are most accurate for steady exercise at moderate speeds and grades. Above about 15% grade, at very slow speeds, and for people with unusual walking economy, the estimates can be off. Treadmill calibration also varies: belt speed and incline readings are not always exact.
Incline for Runners
Runners often set the treadmill to 1% incline to mimic the effort of running outdoors, where air resistance adds a little work that a treadmill lacks. Steeper inclines are a useful way to train for hilly races and to build leg strength without the pounding of fast downhill running. Because the running equation's vertical term is smaller than the walking one, the same incline adds proportionally less to running than to walking.
Calories and Body Weight
Calories scale directly with body weight, because every extra kilogram must be lifted up the slope with every step. A 90 kg person burns nearly 30% more than a 70 kg person on the same incline and speed. That makes incline walking an efficient choice for heavier people who want a hard workout without the impact of running.
Building an Incline Routine
Start with moderate grades of 3 to 6% for 20 to 30 minutes and add a percent or two each week. Warm up on the flat, alternate harder and easier minutes, and finish with a few minutes of flat walking. If your calves or shins ache, reduce the grade and progress more slowly.
Understanding Your Result
The headline gives the flat-ground equivalent speed.
The effort line gives oxygen cost, METs and the increase over 0%.
The calories line gives total calories and the extra from the incline.
The climb line gives the vertical height climbed.
When Should You Use This Calculator?
Use it to compare incline walking with running.
Use it to plan treadmill workouts at a target effort.
Use it to see how many extra calories an incline adds.
Common Mistakes
Holding the rails. It cancels much of the incline.
Jumping straight to steep grades. Build up to protect calves and tendons.
Comparing machine calorie readouts. Many ignore your actual weight.
Assuming incline equals speed one-for-one. The relationship depends on speed.