In general, homeowners can measure their own built-in stoves to ensure that a new unit can fit. However, allowances are small on in-wall appliances, so hiring an expert can help homeowners avoid wasted labor and transportation costs.
Most newer homes have built-in spaces designed to handle standard appliance sizes, which don't vary much. However, even a fraction of an inch can make the difference between a range or oven that fits and one that doesn't. In addition, some spaces may be designed for appliances made by a manufacturer that no longer exists. Unless the replacement model is a perfect match for the measured size, it may be best to hire an expert to take a look.