Biudžetas užbaigus vs Sąmata užbaigus (BAC vs EAC)
Dažniausiai painiojamas dalykas Earned Value Management yra ryšys tarp Biudžeto užbaigus (BAC) ir Sąmatos užbaigus (EAC). Jie atrodo panašiai, abu atspindi „bendrą projekto kainą“, bet jie elgiasi visiškai priešingai.
BAC = kaina, kurią planavote prieš pradedant projektą. Tai yra fiksuota.
EAC = kaina, kurią šiuo metu prognozuojate pabaigai. Ji keičiasi projektui vystantis.
Greitas palyginimas: BAC vs EAC
| Savybė | BAC (Biudžetas užbaigus) | EAC (Sąmata užbaigus) |
|---|---|---|
| Apibrėžimas | Bendras patvirtintas bazinis biudžetas | Prognozuojama bendra projekto kaina |
| Kada nustatoma | Vieną kartą, projekto pradžioje | Perskaičiuojama vykdymo metu |
| Keičiasi? | Tik formaliai peržiūrint bazinę liniją | Taip — atnaujinama kiekvieną ataskaitinį laikotarpį |
| Remiasi | Tik planiniais įvertinimais | Faktinėmis išlaidomis + našumo indeksais |
| Formulė | Σ (visi darbo paketų biudžetai) | BAC / CPI (dažniausia iš 4 formulių) |
| PMBOK ref. | 6-asis leidimas p. 263 | 6-asis leidimas p. 264–265 |
Projekto pradžioje: BAC = EAC
Tuo momentu, kai patvirtinama projekto bazinė linija, BAC ir EAC yra identiški. Jokie darbai neatlikti, jokios faktinės išlaidos nepatirtos, o našumas yra tiksliai toks, kaip planuota. Vos tik prasideda vykdymas ir atsiranda realūs duomenys (AC, EV), EAC pradeda skirtis nuo BAC.
Koks skirtumas tarp BAC ir EAC?
Skirtumas tarp BAC ir EAC yra Dispersija užbaigus (VAC). VAC yra galutinio biudžeto pertekliaus arba trūkumo prognozė remiantis stebimu našumu.
Apsvarstykite šį pavyzdį: programinės įrangos projektas su BAC = $400,000.
- Po 3 mėnesių: AC =
Budget at Completion vs Estimate at Completion (BAC vs EAC)
The most common point of confusion in Earned Value Management is the relationship between Budget at Completion (BAC) and Estimate at Completion (EAC). They look similar, they both represent a "total project cost", but they behave in completely opposite ways.
BAC = the cost you planned before the project started. It is fixed.
EAC = the cost you currently forecast to finish. It changes as the project evolves.
Quick Comparison: BAC vs EAC
Property BAC (Budget at Completion) EAC (Estimate at Completion) Definition Total approved baseline budget Forecasted total project cost When set Once, at project baseline Recalculated throughout execution Changes? Only via formal re-baselining Yes — updated every reporting period Based on Planned estimates only Actual cost + performance indices Formula Σ (all work package budgets) BAC / CPI (most common of 4 formulas) PMBOK ref. 6th Ed. p.263 6th Ed. p.264–265 At Project Start: BAC = EAC
At the moment a project baseline is approved, BAC and EAC are identical. No work has been performed, no actual costs have been incurred, so the forecast equals the plan. As soon as execution begins and real data appears (AC, EV), EAC starts to diverge from BAC.
What is the difference between BAC and EAC?
The key distinction: BAC represents commitment — what was formally agreed with stakeholders. EAC represents reality — what the project is actually projected to cost based on observed performance.
Consider this example: a software project with BAC = $400,000.
- After 3 months: AC = $130,000, EV = $100,000 (25% complete)
- CPI = EV / AC = 100,000 / 130,000 = 0.769 (over budget)
- EAC = BAC / CPI = 400,000 / 0.769 = $520,156
- VAC = BAC − EAC = 400,000 − 520,156 = −$120,156 (projected overrun)
BAC is still $400,000. EAC is now $520,156. The $120,156 gap is what the project manager needs to explain and manage.
Can BAC change during a project?
Yes, but only through a formal process. BAC changes in two scenarios:
- Approved scope change — Additional work packages are added via change control, increasing (or decreasing) the authorized budget.
- Re-baselining — Senior management formally approves a new cost baseline, typically when the original BAC is no longer achievable and a fresh start is needed. This is a significant governance event.
Cost overruns alone NEVER change BAC. They are reflected in EAC and VAC instead.
What does it mean when EAC exceeds BAC?
When EAC exceeds BAC (VAC is negative), the project is projected to finish over budget. The difference represents the forecasted cost overrun. Project managers must report this to stakeholders and take corrective action to drive CPI closer to 1.0 — which reduces EAC.
Research cited in PMBOK shows that once CPI drops below 0.9, it rarely recovers significantly after the 20% completion mark. This makes early EAC forecasting critical.
When EAC is Below BAC
When EAC is less than BAC, VAC is positive — the project is forecast to finish under budget. This is favorable and represents a budget surplus.
The 4 EAC Formulas and How They Relate to BAC
All four PMBOK EAC formulas reference BAC:
EAC₁ = BAC / CPI ← typical performance continues (most common)
EAC₂ = AC + (BAC − EV) ← one-time variance; future at planned rate
EAC₃ = AC + (BAC − EV) / CPI ← sustained CPI impact (= EAC₁)
EAC₄ = AC + (BAC − EV) / (CPI × SPI) ← schedule pressure adds costThe relationship between BAC and each EAC determines VAC = BAC − EAC. The formula you choose reflects your assumption about future performance — but all four start from the same fixed BAC.
Summary Table
→ Calculate BAC, EAC and VAC Instantly 30,000, EV =Situation BAC EAC VAC Meaning On track $500K $500K $0 On budget Cost overrun $500K $560K −$60K Projected to exceed budget Under budget $500K $470K +$30K Forecast surplus Re-baselined $580K $580K $0 New approved baseline Budget at Completion vs Estimate at Completion (BAC vs EAC)
The most common point of confusion in Earned Value Management is the relationship between Budget at Completion (BAC) and Estimate at Completion (EAC). They look similar, they both represent a "total project cost", but they behave in completely opposite ways.
BAC = the cost you planned before the project started. It is fixed.
EAC = the cost you currently forecast to finish. It changes as the project evolves.
Quick Comparison: BAC vs EAC
Property BAC (Budget at Completion) EAC (Estimate at Completion) Definition Total approved baseline budget Forecasted total project cost When set Once, at project baseline Recalculated throughout execution Changes? Only via formal re-baselining Yes — updated every reporting period Based on Planned estimates only Actual cost + performance indices Formula Σ (all work package budgets) BAC / CPI (most common of 4 formulas) PMBOK ref. 6th Ed. p.263 6th Ed. p.264–265 At Project Start: BAC = EAC
At the moment a project baseline is approved, BAC and EAC are identical. No work has been performed, no actual costs have been incurred, so the forecast equals the plan. As soon as execution begins and real data appears (AC, EV), EAC starts to diverge from BAC.
What is the difference between BAC and EAC?
The key distinction: BAC represents commitment — what was formally agreed with stakeholders. EAC represents reality — what the project is actually projected to cost based on observed performance.
Consider this example: a software project with BAC = $400,000.
- After 3 months: AC = $130,000, EV = $100,000 (25% complete)
- CPI = EV / AC = 100,000 / 130,000 = 0.769 (over budget)
- EAC = BAC / CPI = 400,000 / 0.769 = $520,156
- VAC = BAC − EAC = 400,000 − 520,156 = −$120,156 (projected overrun)
BAC is still $400,000. EAC is now $520,156. The $120,156 gap is what the project manager needs to explain and manage.
Can BAC change during a project?
Yes, but only through a formal process. BAC changes in two scenarios:
- Approved scope change — Additional work packages are added via change control, increasing (or decreasing) the authorized budget.
- Re-baselining — Senior management formally approves a new cost baseline, typically when the original BAC is no longer achievable and a fresh start is needed. This is a significant governance event.
Cost overruns alone NEVER change BAC. They are reflected in EAC and VAC instead.
What does it mean when EAC exceeds BAC?
When EAC exceeds BAC (VAC is negative), the project is projected to finish over budget. The difference represents the forecasted cost overrun. Project managers must report this to stakeholders and take corrective action to drive CPI closer to 1.0 — which reduces EAC.
Research cited in PMBOK shows that once CPI drops below 0.9, it rarely recovers significantly after the 20% completion mark. This makes early EAC forecasting critical.
When EAC is Below BAC
When EAC is less than BAC, VAC is positive — the project is forecast to finish under budget. This is favorable and represents a budget surplus.
The 4 EAC Formulas and How They Relate to BAC
All four PMBOK EAC formulas reference BAC:
EAC₁ = BAC / CPI ← typical performance continues (most common)
EAC₂ = AC + (BAC − EV) ← one-time variance; future at planned rate
EAC₃ = AC + (BAC − EV) / CPI ← sustained CPI impact (= EAC₁)
EAC₄ = AC + (BAC − EV) / (CPI × SPI) ← schedule pressure adds costThe relationship between BAC and each EAC determines VAC = BAC − EAC. The formula you choose reflects your assumption about future performance — but all four start from the same fixed BAC.
Summary Table
→ Calculate BAC, EAC and VAC Instantly 00,000 (užbaigta 25%)Situation BAC EAC VAC Meaning On track $500K $500K $0 On budget Cost overrun $500K $560K −$60K Projected to exceed budget Under budget $500K $470K +$30K Forecast surplus Re-baselined $580K $580K $0 New approved baseline - CPI = EV / AC = 100,000 / 130,000 = 0.769 (viršytas biudžetas)
- EAC = BAC / CPI = 400,000 / 0.769 = $520,156
- VAC = BAC − EAC = 400,000 − 520,156 = −
Budget at Completion vs Estimate at Completion (BAC vs EAC)
The most common point of confusion in Earned Value Management is the relationship between Budget at Completion (BAC) and Estimate at Completion (EAC). They look similar, they both represent a "total project cost", but they behave in completely opposite ways.
BAC = the cost you planned before the project started. It is fixed.
EAC = the cost you currently forecast to finish. It changes as the project evolves.
Quick Comparison: BAC vs EAC
Property BAC (Budget at Completion) EAC (Estimate at Completion) Definition Total approved baseline budget Forecasted total project cost When set Once, at project baseline Recalculated throughout execution Changes? Only via formal re-baselining Yes — updated every reporting period Based on Planned estimates only Actual cost + performance indices Formula Σ (all work package budgets) BAC / CPI (most common of 4 formulas) PMBOK ref. 6th Ed. p.263 6th Ed. p.264–265 At Project Start: BAC = EAC
At the moment a project baseline is approved, BAC and EAC are identical. No work has been performed, no actual costs have been incurred, so the forecast equals the plan. As soon as execution begins and real data appears (AC, EV), EAC starts to diverge from BAC.
What is the difference between BAC and EAC?
The key distinction: BAC represents commitment — what was formally agreed with stakeholders. EAC represents reality — what the project is actually projected to cost based on observed performance.
Consider this example: a software project with BAC = $400,000.
- After 3 months: AC = $130,000, EV = $100,000 (25% complete)
- CPI = EV / AC = 100,000 / 130,000 = 0.769 (over budget)
- EAC = BAC / CPI = 400,000 / 0.769 = $520,156
- VAC = BAC − EAC = 400,000 − 520,156 = −$120,156 (projected overrun)
BAC is still $400,000. EAC is now $520,156. The $120,156 gap is what the project manager needs to explain and manage.
Can BAC change during a project?
Yes, but only through a formal process. BAC changes in two scenarios:
- Approved scope change — Additional work packages are added via change control, increasing (or decreasing) the authorized budget.
- Re-baselining — Senior management formally approves a new cost baseline, typically when the original BAC is no longer achievable and a fresh start is needed. This is a significant governance event.
Cost overruns alone NEVER change BAC. They are reflected in EAC and VAC instead.
What does it mean when EAC exceeds BAC?
When EAC exceeds BAC (VAC is negative), the project is projected to finish over budget. The difference represents the forecasted cost overrun. Project managers must report this to stakeholders and take corrective action to drive CPI closer to 1.0 — which reduces EAC.
Research cited in PMBOK shows that once CPI drops below 0.9, it rarely recovers significantly after the 20% completion mark. This makes early EAC forecasting critical.
When EAC is Below BAC
When EAC is less than BAC, VAC is positive — the project is forecast to finish under budget. This is favorable and represents a budget surplus.
The 4 EAC Formulas and How They Relate to BAC
All four PMBOK EAC formulas reference BAC:
EAC₁ = BAC / CPI ← typical performance continues (most common)
EAC₂ = AC + (BAC − EV) ← one-time variance; future at planned rate
EAC₃ = AC + (BAC − EV) / CPI ← sustained CPI impact (= EAC₁)
EAC₄ = AC + (BAC − EV) / (CPI × SPI) ← schedule pressure adds costThe relationship between BAC and each EAC determines VAC = BAC − EAC. The formula you choose reflects your assumption about future performance — but all four start from the same fixed BAC.
Summary Table
→ Calculate BAC, EAC and VAC Instantly 20,156 (prognozuojamas viršijimas)Situation BAC EAC VAC Meaning On track $500K $500K $0 On budget Cost overrun $500K $560K −$60K Projected to exceed budget Under budget $500K $470K +$30K Forecast surplus Re-baselined $580K $580K $0 New approved baseline
Šiame scenarijuje originalus biudžetas (BAC) vis dar yra griežtai $400,000. Jums nedavė daugiau pinigų. Tačiau jūsų prognozė (EAC) rodo, kad jums reikės $520,156, kad baigtumėte. Vadovybei turėsite paaiškinti ir valdyti šį −
Budget at Completion vs Estimate at Completion (BAC vs EAC)
The most common point of confusion in Earned Value Management is the relationship between Budget at Completion (BAC) and Estimate at Completion (EAC). They look similar, they both represent a "total project cost", but they behave in completely opposite ways.
BAC = the cost you planned before the project started. It is fixed.
EAC = the cost you currently forecast to finish. It changes as the project evolves.
Quick Comparison: BAC vs EAC
| Property | BAC (Budget at Completion) | EAC (Estimate at Completion) |
|---|---|---|
| Definition | Total approved baseline budget | Forecasted total project cost |
| When set | Once, at project baseline | Recalculated throughout execution |
| Changes? | Only via formal re-baselining | Yes — updated every reporting period |
| Based on | Planned estimates only | Actual cost + performance indices |
| Formula | Σ (all work package budgets) | BAC / CPI (most common of 4 formulas) |
| PMBOK ref. | 6th Ed. p.263 | 6th Ed. p.264–265 |
At Project Start: BAC = EAC
At the moment a project baseline is approved, BAC and EAC are identical. No work has been performed, no actual costs have been incurred, so the forecast equals the plan. As soon as execution begins and real data appears (AC, EV), EAC starts to diverge from BAC.
What is the difference between BAC and EAC?
The key distinction: BAC represents commitment — what was formally agreed with stakeholders. EAC represents reality — what the project is actually projected to cost based on observed performance.
Consider this example: a software project with BAC = $400,000.
- After 3 months: AC = $130,000, EV = $100,000 (25% complete)
- CPI = EV / AC = 100,000 / 130,000 = 0.769 (over budget)
- EAC = BAC / CPI = 400,000 / 0.769 = $520,156
- VAC = BAC − EAC = 400,000 − 520,156 = −$120,156 (projected overrun)
BAC is still $400,000. EAC is now $520,156. The $120,156 gap is what the project manager needs to explain and manage.
Can BAC change during a project?
Yes, but only through a formal process. BAC changes in two scenarios:
- Approved scope change — Additional work packages are added via change control, increasing (or decreasing) the authorized budget.
- Re-baselining — Senior management formally approves a new cost baseline, typically when the original BAC is no longer achievable and a fresh start is needed. This is a significant governance event.
Cost overruns alone NEVER change BAC. They are reflected in EAC and VAC instead.
What does it mean when EAC exceeds BAC?
When EAC exceeds BAC (VAC is negative), the project is projected to finish over budget. The difference represents the forecasted cost overrun. Project managers must report this to stakeholders and take corrective action to drive CPI closer to 1.0 — which reduces EAC.
Research cited in PMBOK shows that once CPI drops below 0.9, it rarely recovers significantly after the 20% completion mark. This makes early EAC forecasting critical.
When EAC is Below BAC
When EAC is less than BAC, VAC is positive — the project is forecast to finish under budget. This is favorable and represents a budget surplus.
The 4 EAC Formulas and How They Relate to BAC
All four PMBOK EAC formulas reference BAC:
EAC₂ = AC + (BAC − EV) ← one-time variance; future at planned rate
EAC₃ = AC + (BAC − EV) / CPI ← sustained CPI impact (= EAC₁)
EAC₄ = AC + (BAC − EV) / (CPI × SPI) ← schedule pressure adds cost
The relationship between BAC and each EAC determines VAC = BAC − EAC. The formula you choose reflects your assumption about future performance — but all four start from the same fixed BAC.
Summary Table
| Situation | BAC | EAC | VAC | Meaning |
|---|---|---|---|---|
| On track | $500K | $500K | $0 | On budget |
| Cost overrun | $500K | $560K | −$60K | Projected to exceed budget |
| Under budget | $500K | $470K | +$30K | Forecast surplus |
| Re-baselined | $580K | $580K | $0 | New approved baseline |
Ar BAC gali keistis projekto metu?
Taip, bet tik per formalų procesą. BAC keičiasi dviem atvejais:
- Apimties keitimas: Klientas prideda naujų reikalavimų. Tai eina per pokyčių kontrolę, padidinant (arba sumažinant) patvirtintą biudžetą.
- Bazinės linijos peržiūra: Projektas taip nukrypo nuo kurso, kad pradinė bazinė linija nebeturi prasmės, o vadovybė sutinka nustatyti naują bazinę liniją (retai, ir paprastai po didelio valdymo įvykio).
Vien tik išlaidų viršijimas NIEKADA nekeičia BAC. Vietoj to jis atsispindi EAC ir VAC.
Kaip pasirinkti tinkamą EAC formulę
Nors BAC turi tik vieną apibrėžimą, PMBOK pateikia kelis būdus EAC apskaičiuoti, priklausomai nuo projekto sąlygų:
1. Tipinis našumas (EAC = BAC / CPI)
Naudokite, kai tikitės, kad dabartinis CPI (geras ar blogas) išliks toks pats iki projekto pabaigos. Tai yra numatytasis skaičiavimas.
2. Vienkartinė dispersija (EAC = AC + (BAC − EV))
Naudokite, kai ankstesnės išlaidų problemos buvo vienkartinis įvykis (pvz., unikali įrangos gedimo avarija), ir tikitės, kad likę darbai bus atlikti pagal pradinį biudžetą.
3. CPI ir SPI įtaka (EAC = AC + [(BAC − EV) / (CPI × SPI)])
Naudokite, kai projektas vėluoja IR viršija biudžetą, ir vėlavimas turės įtakos būsimoms išlaidoms (pvz., teks mokėti už viršvalandžius, kad pasivytumėte).
4. Vertinimas iš apačios į viršų ETC (EAC = AC + Bottom-up ETC)
Naudokite, kai pradinis įvertinimas buvo iš esmės klaidingas ir jums reikia iš naujo įvertinti visus likusius darbus nuo nulio.
Apibendrinimas
Pagalvokite apie tai kaip apie kelionę automobiliu. BAC yra pinigų suma, kurią planavote išleisti benzinui prieš išvykstant. EAC yra suma, kurią manote, kad išleisite dabar, kai pamatėte, kad jūsų automobilis naudoja daugiau kuro nei tikėtasi.
→ Išbandykite BAC skaičiuoklę nemokamai