Best way to split deliveries across different vehicles?

We've grown to the point where we have a mix of small vans and larger trucks going out every day, but figuring out which deliveries should go on which vehicle has become increasingly difficult. If we overload the vans, they need extra trips, but if we send the larger trucks everywhere, they waste time driving half-empty. Right now we're trying to balance everything manually, and it feels like every change to one route throws off the rest of the day's schedule. Is there a practical way to solve this without spending an hour rebuilding routes every morning?

The hard part isn’t really the stop order anymore, it’s deciding which vehicle should take which load. I’d look for something that lets you enter capacity for each van and truck, then assigns the deliveries before it builds the routes. Quick recalculation matters too, because one late order shouldn’t send you back to moving stops around for another half hour.

Many basic route planners can optimize stop order, but fleet assignment is a different problem. Once you have vans and trucks with different capacities, the system needs to choose the vehicle and the route together. You can use this vehicle routing problem solver: https://routing24.com/ . Add the vehicles with their capacity limits and upload the delivery list. It can split the stops across the fleet and recalculate the routes when the day changes.