Good, and unusually local for a town this size. Sturminster Newton has its own secondary school, which out here is not a given. The primaries are village-sized and scattered across the lanes. Most of the county's graded schools sit at good or better. The constraint is not quality, it is choice, and those two get confused by almost everyone house-hunting.
Ofsted has published a grade for 86 settings across the Dorset authority, and 68 of them sit at good or outstanding, which is roughly four in five. Two hold outstanding, 17 require improvement and one is rated inadequate. A further 52 settings carry no published grade at all, which means not yet inspected under the current arrangements rather than quietly failing. All of those counts describe the whole authority rather than the schools within reach of this town, so they set the weather rather than the forecast for any particular classroom.
Living near a school buys proximity and nothing else. Admission runs on the authority's own rules and each individual school's oversubscription criteria, and in a district where families will happily drive twenty minutes for the right place, a popular school fills from a much wider area than a map implies. Offer day in the spring separates the households that read the admissions criteria from the households that read the property listing, and the criteria are honest about it in advance.
Sturminster Newton High School is the secondary, and having one in the town is the single biggest practical difference between living here and living in the parishes that feed it. William Barnes Primary School is the in-town primary. Yewstock School sits alongside them. Beyond the town, Hazelbury Bryan Primary School and Stalbridge Church of England Primary School serve their own villages, with two further primaries in Marnhull, and the rest of the choice is a matter of which lane you are on when the forms go in. Department for Transport modelling from 2019 puts a primary about 21 minutes away on foot or 9 by car, and a secondary about 19 minutes on foot or 8 by car, which is the kind of geography that makes a school run a walk rather than a scheduling problem.
Schools are one of the stronger reasons to buy in the town rather than in the villages around it. A secondary on the doorstep, primaries inside walking distance, and a county record that mostly stands up is more than most rural towns this size can put on the table.