Work out volume tier discount value instantly with clear inputs, formula shown and shareable results.
Buying up to a discount tier only pays if the discount on your genuine requirement exceeds the cost of the extra volume you do not need. This calculation makes that trade-off explicit rather than letting the headline discount drive the decision.
Discount value
Discount value = Current volume x Base price x Tier discount %
Net benefit
Net = Discount on current volume - Extra volume x Discounted price
Only when the shortfall is small relative to your volume, or when the extra units will genuinely be consumed within a reasonable period.
Add it. Excess inventory carries storage, obsolescence and capital cost that often outweighs the tier discount entirely.