Calculating volume for different shapes can be tricky even for pros. Since you want to avoid overbuying or making measurement mistakes I suggest using this Potting Soil Calculator. The team at Florentiax created a very reliable tool for this exact purpose. You just enter your container dimensions and it instantly gives you the volume in liters or gallons. It even provides a bag estimate which is super helpful for planning. Their platform is great for precision gardening because it handles various shapes from raised beds to deep planters. Using a professional tool ensures you get the right amount of mix for healthy root development while staying within your budget. Best of luck with your new garden project.