Bulletin № 01 — Established 2026 · İstanbul

Browse the toolkit → Read the philosophy
Built for Turkish SMEs + global
Language EN / TR
Format Single HTML file
Tools live 02 / ∞
Status Shipping
§ 01 — The toolkit Updated April 2026

Tool / 01 — LE-INV Shipping

  • Economic Order Quantity with sensitivity bands
  • Safety stock — combined demand + lead-time variance
  • Reorder point + cycle time on operating calendar
  • Interactive cost breakdown
  • Plain-language interpretation block
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Tool / 02 — LE-FCT Shipping

  • Four forecasting models side-by-side
  • Automatic best-model selection by MAPE
  • CSV drag-and-drop — any ERP export works
  • Configurable horizon: 1 to 24 periods
  • MAPE / MAE / accuracy bars for every model
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§ 02 — Philosophy Why single-file tools
Our position

Three principles

i.

ii.

iii.

§ 03 — Readership Who buys these tools

  • A
    Production & operations managers
    Manufacturing plants, 20–500 employees
  • B
    Supply chain analysts
    S&OP, demand planning, procurement
  • C
    IE students & young graduates
    Learning by doing, not reading textbooks
  • D
    SME owners wearing every hat
    Running ops, finance, and everything else
Direct line

Email
hello@letta.earth
→
LinkedIn
Letta Earth
→
Storefront
letta.gumroad.com
→
Writing
medium.com/@letta.earth
→