No need for a big fish scale. Just find an airport with a long runway with no obstructions near the end. Then try taking off with less than full throttle. How much less? Try it at 95% power. Then 90% and so on until you find the minimum acceptable to get safely airborne. Oh, and be sure to do this on a hot summer day with high density altitude. You migh be surprised how quickly your plane’s performance degrades.