C172 pilot reported engine roughness and subsequent engine failure led to an off-airport landing. There were no injuries or aircraft damage reported.

Narrative

The flight began at ZZZ2. Following the POH checklist; I completed preflight and checked oil (5 and 2/3 oil) and fuel. I had 14 and 12 gallons in each tank; I can't remember which was in the R or L. I had sumped the tanks and done a thorough preflight as my commercial check ride was the following day. I started the engine; taxied to the ZZZ2 run-up area; and let the plane warm up for 8 minutes. I have a timer in the aircraft and had started it; so I know how long it was. I completed a full run-up without any issues. No significant mag drop or differential drop between R and L. No signs of any carburetor icing. The plane ran smoothly at full idle with full carburetor heat applied. I made a radio call on CTAF and took off to ZZZ1; on the way to ZZZ; to top off my fuel so it would be ready for the check ride exam in the morning. Upon landing at ZZZ1; I had no issues. The plane ran great on the way there. Landed; off at the first taxiway; and taxied to fuel. I topped off both tanks and then taxied back to the ZZZ1 run-up area; where I performed a second complete engine run-up. Again no issues.I took off out of ZZZ1. I obtained the ZZZ ATIS 1; and reported my position and intentions: to complete two touch-and-go's followed by a full-stop landing. I planned to park the plane for the night and stay in a nearby hotel for the exam in the morning. Tower instructed an R base; reporting 2 mile R base and clear touch-and-go. I complied and did my first touch-and-go but did not land because I overshot my touchdown point (I was practicing a short-field landing). I went full power; carburetor heat off; and began climbing upwind. No issues. I entered mid-field right downwind for Runway XX and spoke with the tower; I was cleared to land; cleared for another touch-and-go; followed by a full stop. I completed this loop in the pattern without any issues. I landed this time and took back off; re-entering the upwind. Just before reaching the shoreline; I began to experience mild engine roughness. This seemed similar to when I picked up some carburetor ice; so I pulled the carburetor heat on; but there was no change in performance or engine roughness; so I placed the carburetor heat back off. As I crossed the shoreline and turned downwind; the engine roughness quickly moved from mild to moderate. This was when I made my first call to the tower. I told them about engine roughness and that I would like to do a 180 and land [Runway] XY. Tower approved; and I attempted to land. I gained too much altitude (I am still trying to figure out what my indicator was reading) as I had been trying to have as much room between myself and the ground as possible as soon as the roughness started. However; once facing the runway; it was clear I was high and fast; and there was a tailwind landing [Runway] XY. As the 1;000 foot marker approached; it became clear I would not be slow enough to land without damaging the plane or overrunning the runway and ending up on the road. I contacted tower again; letting them know I won't be able to land on Runway XY and that I would be departing XY. I thought the situation might be similar to the take-off of Runway XX; so I tried to gain altitude with a power setting between 1;500-2;000 RPM (as I was only getting any form of power here; full power; the engine felt like it was going to die and the same at idle). I could not gain much altitude; and it became clear as I tried to make another 180 to land [Runway] XX that I would not make the runway. It was in this turn that the engine completely failed. I told the tower I was aborting landing XX and planned to aim for a field. I found a field just north of my position and turned to land there. I put the plane down in a grass field north of the [Runway] XX numbers. It was a soft field landing with no prop strike. I could communicate with the tower once on the ground in the field and attempted to give them my location. Locals came to the field; and the tower was able to call emergency services for me. I told the tower I was the only person on board; there was no damage to the aircraft or myself; and the plane was safe in a field.