Overview
TBW means terabytes written over a specified endurance rating. DWPD expresses the number of times the drive's rated capacity can be written per day over the stated endurance period.
Engineering considerations
A simple conversion is DWPD = TBW ÷ (drive capacity × number of days in the rated period). The rating is a vendor qualification metric under defined conditions, not a guarantee that a drive will fail immediately after reaching TBW.
How to plan it
Workload matters. Random writes, write amplification, temperature, over-provisioning and firmware behaviour can influence NAND wear and performance. Vendor specifications should be used for final procurement decisions.
Design implications
Estimate the application's daily write volume, include write amplification where the platform provides a defensible figure, and compare the result with the SSD's published endurance class.
Operational considerations
Use the SSD Endurance Calculator for an initial TBW/DWPD comparison, then validate against the manufacturer's qualification data.