Thailand's manufacturing production index (MPI) in March dropped 2.54% from a year earlier, led by lower production of computers, steel and rubber products, the Industry Ministry said on Tuesday.
That compares with a forecast fall of 2.7% in a Reuters poll, and against February's 1.6% contraction.
Capacity utilisation was at 74.38% in March, up from February's 69%.
The ministry expects the MPI to rise between 2% and 3% this year, after 2018's 2.8% rise.