The Earth has an average density of about 5500 kg/m^3. For a small planet, the density would be pretty similar throughout. Therefore the force of gravity you would experience on a planet with Earth density is: Your Mass * 5500 * 4/3pi * r^3 / r^2 * 6.6723 * 10^-11
This is equal to about 1.456 * 10^-6 * Your Mass * Radius of Small Planet.
(I know, if you check the multiplication, it doesn't work out, that is because the simplified equation I wrote down is more accurate)
This is also assuming all of your mass is concentrated on your feet, this is not true, but the overall equations remain the same. We could try to integrate the force on every cross-section of your body combined with the cross-sections density. This statement shows how complicated it would be to accurately find the force. Instead we could just assume your mass is concentrated halfway up your body.
So our new equation is: 1.456 * 10^-6 * Your Mass * Radius of Mini Planet Cubed / (Radius of Mini Planet + Half of Your Height) Squared
An excellent article on what it would feel like to walk around, stand on, and jump on a mini planet is found at the following link:
When the radius was increased, you would feel stronger gravity, but less tidal forces. When the radius was decreased, you would feel weaker gravity, but more tidal forces.
Although the tidal forces involved may be small, it would feel as though you were laying on a ball, or laying with your head near the center of a merry-go-round.
Escape Velocity for a planet is found with the formula sqrt(2GM/r). An average human can jump at a velocity of .153 m/s upward. So to jump off of a mini planet with Earth density, the planet would have to be smaller than 87.33 m in radius. An interesting point noted in the article is that an object will escape the pull of a planet if the object is moving at escape velocity in any direction, provided that it is not moving at the planet. An average human can run at 5.6 m/s. So a mini-planet would have to be smaller than 3193.81 m in radius to run off of it. To just walk off a mini planet, it would have to be smaller than 798.45 m in radius.