FTE Adjustment Model: Modeling Productivity Ramps During Employee Leave

Overview

Many companies need to track FTE (Full-Time Equivalent) values for planning, budgeting, and resource allocation. When employees take extended leave, most systems treat capacity as a binary state: either 1.0 FTE (fully present) or 0.0 FTE (absent).

In reality, employee productivity doesn't drop instantly to zero when leave begins, nor does it snap back to 100% immediately upon return. Employees typically experience a gradual ramp-down period before extended leave as they transfer knowledge and wrap up projects. Similarly, they need a ramp-up period after returning to reintegrate and regain full productivity.

This model addresses that gap by calculating adjusted FTE values that account for these transition periods, giving stakeholders a more accurate picture of available capacity.

Business Goals

More Accurate Planning

Realistic Budget Forecasts

Better Resource Allocation

Improved Capacity Models

How It Works

The model applies weighted FTE multipliers during four distinct phases:

Ramp Down Start

Ramp Down Spillover

Absence

Ramp Up Start

Ramp Up Spillover

Ramp Down: 14 calendar days before absence begins, FTE is weighted at 75%
Absence: During the leave period, FTE is 0%
Ramp Up: 28 calendar days after absence ends, FTE is weighted at 50%

Phase Breakdown

The algorithm breaks the ramp-down and ramp-up periods into four potential monthly adjustments, each with its own calculation:

Ramp Down Start

Month where ramp-down begins

P₁ =

D₁

M₁

R₁

M₁

× 0.75

D₁ = Days before ramp down

M₁ = Total days in month

R₁ = Days during ramp down (up to 14)

Effect: Adds unweighted FTE before ramp down to weighted FTE during ramp down. If R₁ < 14 days, remaining ramp down days spill into P2

Ramp Down Spillover

Continuation into next month (if needed)

P₂ =

R₂

M₂

× 0.75

R₂ = Days remaining from P1

M₂ = Total days in spillover month

Effect: If ramp down extends beyond P1 month end, applies 75% FTE weighting to remaining ramp down days. Otherwise, 0.

Ramp Up Start

Month where ramp-up begins

P₃ =

R₃

M₃

× 0.5 +

D₃

M₃

R₃ = Days during ramp up (up to 28)

M₃ = Total days in month

D₃ = Days after ramp up ends

Effect: Adds weighted FTE during ramp up to unweighted FTE after ramp up. If ramp up extends beyond month end, remaining ramp up days spill into P4

Ramp Up Spillover

Continuation into next month (if needed)

P₄ =

R₄

M₄

× 0.5 +

D₄

M₄

R₄ = Days remaining from P3

M₄ = Total days in spillover month

D₄ = Days after ramp up ends

Effect: If ramp up extends beyond P3 month end, applies 50% FTE weighting to remaining ramp up days, then unweighted FTE after. Otherwise, 0.

Algorithm Implementation

We perform the same basic calculation on each period:
(Unweighted Days / Total Days) + ((Ramp Weight Factor) × (Weighted Days / Total Days))

The Ramp Weight Factor is 0.75 for ramp-down periods (P1, P2) and 0.50 for ramp-up periods (P3, P4)

BEG_RD_PD as P1_PD,
(D1 / M1) + ((R1 / M1) * 0.75) as P1DAYS,

BEG_ABS_PD as P2_PD,
((R2 / M2) * 0.75) as P2DAYS,

END_ABS_PD as P3_PD,
((R3 / M3) * 0.5) + (D3 / M3) as P3DAYS,

END_RU_PD as P4_PD,
((R4 / M4) * 0.5) + (D4 / M4) as P4DAYS

What it does: Calculates the FTE adjustment for each phase using a consistent two-part formula:

Phase 1 (Ramp-Down Start):
Unweighted Days / Days in Month — The proportion of the month before ramp-down begins (full FTE)
+
Weighted Days / Days in Month × 0.75 — The proportion of the month during ramp-down (capped at 14 days)

Phase 2 (Ramp-Down Spillover):
Weighted Days / Days in Month × 0.75 — If ramp-down extends into the next month, the remaining days are weighted at 75%

Phase 3 (Ramp-Up Start):
Weighted Days / Days in Month × 0.5 — The proportion of the month during ramp-up (capped at 28 days)
+
Unweighted Days / Days in Month — The proportion of the month after ramp-up ends (full FTE)

Phase 4 (Ramp-Up Spillover):
Weighted Days / Days in Month × 0.5 — If ramp-up extends into the next month, the remaining ramp days are weighted at 50%
+
Unweighted Days / Days in Month — The proportion of the month after ramp-up ends (full FTE)

This approach ensures that FTE adjustments are prorated correctly based on how many days each phase impacts in each month.

Employee	Ramp Down Start	Ramp Down End	P1 FTE Calculation	P2 FTE Calculation
Employee 1	2024-07-21	2024-08-04	(20/31) + ((11/31) × 0.75)	((3/31) × 0.75)
Employee 2	2025-03-15	2025-03-29	(14/31) + ((14/31) × 0.75)	0
Employee 3	2025-05-08	2025-05-22	(7/31) + ((14/31) × 0.75)	0

* Note that the ramp-down for Employee 1 extends into the next month, creating a non-zero P2 value.

Unpivot and Aggregate by Employee / Month

After applying the algorithm to all four phases, we wind up with a dataset that looks like this:

Employee	P1	P1 FTE	P2	P2 FTE	P3	P3 FTE	P4	P4 FTE
Employee 1	202407	0.911	202408	0.073	202501	0.161	202502	0.679
Employee 2	202503	0.790	NULL	0.000	202507	0.145	202508	0.694
Employee 3	202505	0.565	NULL	0.000	202509	0.500	NULL	0.000

SELECT t.*

into #FTE_TABLE

FROM #tmp

CROSS APPLY (

    VALUES

        (EMPLOYEE_NAME, [P1 MONTH], [P1 FTE])

      , (EMPLOYEE_NAME, [P2 MONTH], [P2 FTE])

      , (EMPLOYEE_NAME, [P3 MONTH], [P3 FTE])

      , (EMPLOYEE_NAME, [P4 MONTH], [P4 FTE])

) t(EMPLOYEE_NAME, MONTH, FTE)

-- Final aggregation into Employee/Month grouping

select 
  EMPLOYEE_NAME, 
  MONTH, 

  SUM(FTE) as FTE

from #FTE_TABLE

group by EMPLOYEE_NAME, MONTH

What it does: The CROSS APPLY with VALUES acts as an unpivot, transforming the wide format (P1, P2, P3, P4 columns) into a long format with one row per employee-month combination. This makes it easy to aggregate and report on FTE by month.

Employee	Month	FTE
Employee 1	202407	0.911
Employee 1	202408	0.073
Employee 1	202501	0.161
Employee 1	202502	0.679
Employee 2	202503	0.790
Employee 2	202507	0.145
Employee 2	202508	0.694
Employee 3	202505	0.565
Employee 3	202509	0.500

Results Visualized

Gradual Transitions: FTE values don't drop instantly to 0. They follow a graduated path, showing that productivity ramps down over time as employees prepare for leave.
Recovery Period: FTE values climb back gradually rather than jumping to full capacity. This captures the reintegration period that naturally occurs after extended leave.
Staggered Impact: Employee 1's ramp-down spans two months while the others span one month. The model adapts to different calendar alignments and leave timing.
Planning Accuracy: Stakeholders can more accurately forecast capacity needs, budget requirements, and staffing gaps rather than measuring FTE as "here/not here".

Bottom Line: The model takes in BEG_ABS and END_ABS dates and transforms them into a nuanced capacity forecast that accounts for employee transition periods, providing more realistic FTE counts for budgeting and resource allocation decisions.