Decide whether you need true tomato-juice thinness (drinks/simmering liquids) or just tomato flavor (soups/sauces).
Pick the closest option from the grouping: strained crushed tomatoes or reconstituted tomato paste for best match.
Use the listed ratio, then adjust: add a splash of water for thickness or a pinch of salt/acid (lemon or vinegar) for balance.
If using anything with solids (crushed/diced), strain through a fine sieve for 3-5 minutes for a smoother pour.
Taste after 2 minutes of heating in the dish so the flavor settles and the acidity reads correctly.