Without a bench, a dumbbell press can still be possible from the floor. The upper arms meet the floor as the weights descend, limiting how far the elbows travel behind the body. That makes the movement different from a bench press rather than simply a cheaper version of it.
The limited range may appeal when you want a clearly defined lower position. It is not a universal solution for shoulder pain. A movement that hurts should be assessed on its own terms, and an individual restriction may require a different exercise altogether.
Before choosing weights, consider getting down and getting up. If floor transitions are difficult, a wall push-up or suitable machine may be easier to manage. You should not have to hold heavy dumbbells while inventing a way to sit up.
Rehearse the whole sequence
Ask a qualified instructor to demonstrate the entry, press and exit with light dumbbells. Use clear floor space on a firm, nonslip surface. A thin mat can make contact more comfortable; a soft mattress changes support and is not equivalent to the floor.
Once positioned, keep the weights under control over the arms, and lower deliberately until the upper arms make gentle contact. Do not bounce the elbows against the floor. Press back through a comfortable path, keeping the weights from drifting toward your face or far outside your control.
Breathing and grip matter here as they do in other pressing exercises. Use a load that lets you pay attention to both, rather than holding your breath through a long struggle. Stop with enough capacity to complete the planned exit. Training to the point that you have to drop the weights beside your head is not a sensible way to learn the movement.
A barbell floor press introduces different rack and safety requirements. It is not interchangeable with the light dumbbell example simply because both begin on the floor. Do not attempt a heavy barbell setup without appropriate equipment, instruction and a safe plan for an unfinished repetition.
Compare the right numbers
Because the floor limits the descent, a floor-press weight cannot be used as a direct prediction of your bench press. Record the variation accurately. When your goal is general pushing strength, choosing between floor, bench, wall or machine is a matter of fit, access and control. You do not need to graduate through them in a fixed order, and a convenient version can remain part of your routine for as long as it serves the intended purpose.
