A gas turbine engine comprising a gas turbine engine core comprising high and low pressure compressors (15, 14) and high and low pressure turbines (17, 19), the high pressure compressor and high pressure turbine being coupled by a high pressure shaft, and the low pressure compressor and low pressure turbine being coupled by a low pressure shaft, the engine further comprising a fan coupled to the low pressure shaft by a reduction gearbox, wherein: the low pressure compressor comprises no more than two compressor stages (41, 42), and the low and high pressure compressor (14, 15) together define a cruise overall core pressure ratio of between 30 and 50, and wherein the engine comprises a core inlet passage extending between a core inlet and an inlet of the low pressure compressor, a first radius change ΔR 1 being defined by a difference between a radius (R inlet) at a mid-height of the leading edge of an engine section stator aerofoil at an axially forward end of the core inlet passage, and an outlet radius R outlet of the core inlet passage measured at a mid-height at a leading edge of a first rotor stage of the low pressure compressor, a first duct loading Δ R 1 / L 1 being defined by a ratio of the first radius change ΔR 1 to a first axial length L of the inlet duct between the axially forward end and the leading edge of the first stage of the low pressure compressor, wherein the first duct loading is between 0.35 and 0.55, and wherein the first compressor rotor of the low pressure compressor defines a hub to tip ratio defined by a radius of a root of a leading edge of the compressor rotor divided by a radius of a tip at the leading edge of the compressor rotor, wherein the hub to tip ratio is between 0.6 and 0.75; characterised in that the engine core comprises an inter-compressor duct extending between an outlet of the low pressure compressor and an inlet of the high pressure compressor, the inter-compressor duct defining a second duct loading ΔR 2 /L 2 comprising a second radius change ΔR 2 divided by a second axial length L 2 of the inter-compressor duct, wherein the second radius change ΔR 2 can be determined by a difference between a radius R IPC of the inter-compressor passage measured at a mid-height of the trailing edge of an axially rearmost low pressure compressor rotor at an axially forward end of the inter-compressor passage, and a radius R HPC of the inter-compressor passage measured at a mid-height at a leading edge of a first rotor stage of the high pressure compressor, wherein the second duct loading is between 0.3 and 0.6. the low pressure compressor comprises no more than two compressor stages (41, 42), and the low and high pressure compressor (14, 15) together define a cruise overall core pressure ratio of between 30 and 50, and wherein the engine comprises a core inlet passage extending between a core inlet and an inlet of the low pressure compressor, a first radius change ΔR 1 being defined by a difference between a radius (R inlet) at a mid-height of the leading edge of an engine section stator aerofoil at an axially forward end of the core inlet passage, and an outlet radius R outlet of the core inlet passage measured at a mid-height at a leading edge of a first rotor stage of the low pressure compressor, a first duct loading Δ R 1 / L 1 being defined by a ratio of the first radius change ΔR 1 to a first axial length L of the inlet duct between the axially forward end and the leading edge of the first stage of the low pressure compressor, wherein the first duct loading is between 0.35 and 0.55, and wherein the first compressor rotor of the low pressure compressor defines a hub to tip ratio defined by a radius of a root of a leading edge of the compressor rotor divided by a radius of a tip at the leading edge of the compressor rotor, wherein the hub to tip ratio is between 0.6 and 0.75; characterised in that the engine core comprises an inter-compressor duct extending between an outlet of the low pressure compressor and an inlet of the high pressure compressor, the inter-compressor duct defining a second duct loading ΔR 2 /L 2 comprising a second radius change ΔR 2 divided by a second axial length L 2 of the inter-compressor duct, wherein the second radius change ΔR 2 can be determined by a difference between a radius R IPC of the inter-compressor passage measured at a mid-height of the trailing edge of an axially rearmost low pressure compressor rotor at an axially forward end of the inter-compressor passage, and a radius R HPC of the inter-compressor passage measured at a mid-height at a leading edge of a first rotor stage of the high pressure compressor, wherein the second duct loading is between 0.3 and 0.6.