Lowering the response times of fire and rescue services (FRS) can reduce costs and the risk of fatalities in emergencies. Ensuring everyone can be reached by the FRS as quickly as possible is therefore a key objective for planners, who often rely on estimated response times to know where response times are long. To be reliable, such estimations need to be validated against real response times. Therefore, this study investigates the spatial patterns of FRS in Sweden in 2018, and compares how estimated and real response times correspond, as well as what factors explain under- or overestimation of the real times. Network analysis performed in a Geographical Information System (GIS) and regression modelling underpin the methodology. In most FRS events (81.3%), estimated response times are shorter than real response times with an average of 83.6 s. Both real and estimated response times are highest in rural municipalities. However, on average, underestimations are larger in urban municipalities. Response times also tend to be underestimated in municipalities with formalized cooperation agreements. Joint organization of FRS resources is thus not necessarily an effective way to reduce response times, with implications for the way FRS is delivered. This study highlights the heterogeneous spatial patterns of difference between estimated and real response times, and shows the importance of being event and area specific when planning the FRS system.