Budžeta pabeidzot formula (BAC formula)
Budžeta pabeidzot (BAC) formula ir Earned Value Management pamats. Tā nosaka kopējo apstiprināto budžetu visiem projekta darbiem. Saskaņā ar PMBOK 6. izdevumu (263. lpp.), BAC formula ir:
Vienkāršiem vārdiem: katra darba pakete, izmaksu kategorija un neparedzēto gadījumu rezerve tiek novērtēta un sasummēta. Kopsumma ir jūsu BAC. Kad tā ir apstiprināta bāzes līnijā, tā ir fiksēta — BAC nemainās, kad tiek pārsniegtas izmaksas. Mainās tikai Estimate at Completion (EAC).
BAC formula EVM kontekstā
Budžeta pabeidzot formula tieši ietekmē katru citu EVM metriku:
| Metrika | Izmanto BAC? | Formula |
|---|---|---|
| Planned Value (PV) | ✓ | % Plānotais × BAC |
| Earned Value (EV) | ✓ | % Pabeigtais × BAC |
| CPI | Netieši | EV / AC |
| EAC (tipiska) | ✓ | BAC / CPI |
| VAC | ✓ | BAC − EAC |
| TCPI | ✓ | (BAC − EV) / (BAC − AC) |
Neprecīzs BAC padara katru nākamo EVM metriku neuzticamu. Pareiza BAC formulas izmantošana ir vissvarīgākais solis projekta izmaksu pārvaldībā.
5 metodes BAC aprēķināšanai
Nav viena algoritma BAC izveidošanai. PMBOK definē vairākas novērtēšanas pieejas, katra piemērota atšķirīgam projekta definīcijas līmenim:
1. Augšupēja novērtēšana (Visprecīzākā)
Novērtējiet katru atsevišķo darba paketi, pēc tam sasummējiet visus novērtējumus. Precizitāte: ±5–10%. Nepieciešama detalizēta apjoma definīcija. Šo pieeju izmanto mūsu BAC Builder cilnē.
2. Analoģiskā novērtēšana
Izmantojiet datus no salīdzināma pabeigta projekta kā sākumpunktu. Precizitāte: ±25–75%. Ātra, bet atkarīga no atbilstošu vēsturisko datu esamības. Vislabāk agrīnās stadijas budžetiem.
3. Parametriskā novērtēšana
Atvasiniet izmaksas no statistiskās sakarības starp projekta apjomu un vienības izmaksām. Precizitāte: ±10–20%. Izplatīta būvniecībā (izmaksas/m²), programmatūrā ($izmaksas/funkcijas punkts) un ražošanā.
4. Trīspunktu novērtēšana (PERT)
Novērtējiet trīs scenārijus, lai iegūtu ar varbūtību svērtu novērtējumu. PERT ņem vērā grafika un izmaksu nenoteiktību, padarot to uzticamāku nekā vienpunkta novērtējums.
5. Ekspertu vērtējums
Konsultējieties ar kvalificētiem jomas ekspertiem, ja nav salīdzināmu datu. Apvienots ar jebkuru no iepriekš minētajām metodēm. Precizitāte pilnībā atkarīga no eksperta pieredzes.
Praktisks piemērs: BAC formulas pielietošana
Uzņēmums plāno biroja renovācijas projektu. Projekta vadītājs katrai darba paketei izmanto augšupēju novērtēšanu:
| Darba pakete | Budžets | |||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Demontāža un vietas sagatavošana | $80,000 | |||||||||||||||||||||||||||||||||||||||||
| Būvkonstrukciju darbi | $220,000 | |||||||||||||||||||||||||||||||||||||||||
| Elektrība un santehnika | Budget at Completion Formula (BAC Formula)The Budget at Completion (BAC) formula is the foundation of Earned Value Management. It defines the total approved budget for all project work. Per PMBOK 6th Edition (p.263), the BAC formula is: BAC = Sum of all budgets established for the work to be performed In plain terms: every work package, cost category, and contingency reserve is estimated and summed. The total is your BAC. Once approved at baseline, it is fixed — BAC does not change when costs overrun. Only the Estimate at Completion (EAC) changes. BAC Formula in Context of EVMThe Budget at Completion formula feeds directly into every other EVM metric:
An inaccurate BAC makes every downstream EVM metric unreliable. Getting the BAC formula right is the most important step in project cost management. 5 Methods to Calculate BACThere is no single algorithm for building BAC. PMBOK defines several estimation approaches, each suited to a different level of project definition: 1. Bottom-Up Estimation (Most Accurate)BAC = Σ (cost of each work package) Estimate every individual work package, then sum all estimates. Accuracy: ±5–10%. Requires detailed scope definition. This is the approach used in our BAC Builder tab. 2. Analogous EstimationBAC = Actual cost of similar past project × adjustment factor Use data from a comparable completed project as the starting point. Accuracy: ±25–75%. Fast but relies on having relevant historical data. Best for early-stage budgets. 3. Parametric EstimationBAC = unit cost × quantity (e.g. $/m² × project area) Derive cost from a statistical relationship between project scope and unit cost. Accuracy: ±10–20%. Common in construction (cost/m²), software ($cost/function point), and manufacturing. 4. Three-Point Estimation (PERT)BAC = (Optimistic + 4 × Most Likely + Pessimistic) / 6 Weight three scenarios to produce a probability-weighted estimate. PERT accounts for schedule and cost uncertainty, making it more reliable than a single-point estimate. 5. Expert JudgementConsult qualified subject matter experts when no comparable data exists. Combined with any of the above methods. Accuracy depends entirely on expert experience. Worked Example: Applying the BAC FormulaA company is planning an office renovation project. The project manager applies bottom-up estimation to each work package:
This is the BAC: $990,000. The management reserve ($50,000) is held separately and is NOT part of the BAC formula. If by month 4 the project has spent $420,000 on 38% of the work, the EVM metrics become:
What BAC Does NOT IncludeKey Rule: BAC = Cost Baseline = Direct Costs + Indirect Costs + Contingency Reserve. BAC does not include Management Reserve (held by management for unknown-unknown risks). BAC + Management Reserve = Total Project Budget. Why BAC Must Never Change Mid-ProjectA cost overrun does NOT change BAC. If your project overspends, you track this through:
If the project scope formally changes (approved change request), only then can the BAC be re-baselined. This is called a budget revision and requires formal change control. → Build Your BAC with Our Free Calculator 80,000 | |||||||||||||||||||||||||||||||||||||||||
| Iekšējā apdare | $340,000 | |||||||||||||||||||||||||||||||||||||||||
| Projektu vadība | $80,000 | |||||||||||||||||||||||||||||||||||||||||
| Neparedzēto gadījumu rezerve (10%) | $90,000 | |||||||||||||||||||||||||||||||||||||||||
| BAC (Izmaksu bāzes līnija) | $990,000 | |||||||||||||||||||||||||||||||||||||||||
| Vadības rezerve (5%) | $50,000 | |||||||||||||||||||||||||||||||||||||||||
| Kopējais projekta budžets | Budget at Completion Formula (BAC Formula)The Budget at Completion (BAC) formula is the foundation of Earned Value Management. It defines the total approved budget for all project work. Per PMBOK 6th Edition (p.263), the BAC formula is: BAC = Sum of all budgets established for the work to be performed In plain terms: every work package, cost category, and contingency reserve is estimated and summed. The total is your BAC. Once approved at baseline, it is fixed — BAC does not change when costs overrun. Only the Estimate at Completion (EAC) changes. BAC Formula in Context of EVMThe Budget at Completion formula feeds directly into every other EVM metric:
An inaccurate BAC makes every downstream EVM metric unreliable. Getting the BAC formula right is the most important step in project cost management. 5 Methods to Calculate BACThere is no single algorithm for building BAC. PMBOK defines several estimation approaches, each suited to a different level of project definition: 1. Bottom-Up Estimation (Most Accurate)BAC = Σ (cost of each work package) Estimate every individual work package, then sum all estimates. Accuracy: ±5–10%. Requires detailed scope definition. This is the approach used in our BAC Builder tab. 2. Analogous EstimationBAC = Actual cost of similar past project × adjustment factor Use data from a comparable completed project as the starting point. Accuracy: ±25–75%. Fast but relies on having relevant historical data. Best for early-stage budgets. 3. Parametric EstimationBAC = unit cost × quantity (e.g. $/m² × project area) Derive cost from a statistical relationship between project scope and unit cost. Accuracy: ±10–20%. Common in construction (cost/m²), software ($cost/function point), and manufacturing. 4. Three-Point Estimation (PERT)BAC = (Optimistic + 4 × Most Likely + Pessimistic) / 6 Weight three scenarios to produce a probability-weighted estimate. PERT accounts for schedule and cost uncertainty, making it more reliable than a single-point estimate. 5. Expert JudgementConsult qualified subject matter experts when no comparable data exists. Combined with any of the above methods. Accuracy depends entirely on expert experience. Worked Example: Applying the BAC FormulaA company is planning an office renovation project. The project manager applies bottom-up estimation to each work package:
This is the BAC: $990,000. The management reserve ($50,000) is held separately and is NOT part of the BAC formula. If by month 4 the project has spent $420,000 on 38% of the work, the EVM metrics become:
What BAC Does NOT IncludeKey Rule: BAC = Cost Baseline = Direct Costs + Indirect Costs + Contingency Reserve. BAC does not include Management Reserve (held by management for unknown-unknown risks). BAC + Management Reserve = Total Project Budget. Why BAC Must Never Change Mid-ProjectA cost overrun does NOT change BAC. If your project overspends, you track this through:
If the project scope formally changes (approved change request), only then can the BAC be re-baselined. This is called a budget revision and requires formal change control. → Build Your BAC with Our Free Calculator ,040,000 |
Tas ir BAC: $990,000. Vadības rezerve ($50,000) tiek turēta atsevišķi un NAV daļa no BAC formulas. Ja līdz 4. mēnesim projektam iztērēti $420,000 par 38% darbu, EVM metrikas kļūst šādas:
- AC = $420,000
- EV = 38% × $990,000 = $376,200
- CPI = $376,200 / $420,000 = 0.896 (pārsniedz budžetu)
- EAC = $990,000 / 0.896 =
Budget at Completion Formula (BAC Formula)
The Budget at Completion (BAC) formula is the foundation of Earned Value Management. It defines the total approved budget for all project work. Per PMBOK 6th Edition (p.263), the BAC formula is:
BAC = Sum of all budgets established for the work to be performedIn plain terms: every work package, cost category, and contingency reserve is estimated and summed. The total is your BAC. Once approved at baseline, it is fixed — BAC does not change when costs overrun. Only the Estimate at Completion (EAC) changes.
BAC Formula in Context of EVM
The Budget at Completion formula feeds directly into every other EVM metric:
Metric Uses BAC? Formula Planned Value (PV) ✓ % Planned × BAC Earned Value (EV) ✓ % Complete × BAC CPI Indirectly EV / AC EAC (typical) ✓ BAC / CPI VAC ✓ BAC − EAC TCPI ✓ (BAC − EV) / (BAC − AC) An inaccurate BAC makes every downstream EVM metric unreliable. Getting the BAC formula right is the most important step in project cost management.
5 Methods to Calculate BAC
There is no single algorithm for building BAC. PMBOK defines several estimation approaches, each suited to a different level of project definition:
1. Bottom-Up Estimation (Most Accurate)
BAC = Σ (cost of each work package)Estimate every individual work package, then sum all estimates. Accuracy: ±5–10%. Requires detailed scope definition. This is the approach used in our BAC Builder tab.
2. Analogous Estimation
BAC = Actual cost of similar past project × adjustment factorUse data from a comparable completed project as the starting point. Accuracy: ±25–75%. Fast but relies on having relevant historical data. Best for early-stage budgets.
3. Parametric Estimation
BAC = unit cost × quantity (e.g. $/m² × project area)Derive cost from a statistical relationship between project scope and unit cost. Accuracy: ±10–20%. Common in construction (cost/m²), software ($cost/function point), and manufacturing.
4. Three-Point Estimation (PERT)
BAC = (Optimistic + 4 × Most Likely + Pessimistic) / 6Weight three scenarios to produce a probability-weighted estimate. PERT accounts for schedule and cost uncertainty, making it more reliable than a single-point estimate.
5. Expert Judgement
Consult qualified subject matter experts when no comparable data exists. Combined with any of the above methods. Accuracy depends entirely on expert experience.
Worked Example: Applying the BAC Formula
A company is planning an office renovation project. The project manager applies bottom-up estimation to each work package:
Work Package Budget Demolition & Site Prep $80,000 Structural Work $220,000 Electrical & Plumbing $180,000 Interior Fit-Out $340,000 Project Management $80,000 Contingency Reserve (10%) $90,000 BAC (Cost Baseline) $990,000 Management Reserve (5%) $50,000 Total Project Budget $1,040,000 This is the BAC: $990,000. The management reserve ($50,000) is held separately and is NOT part of the BAC formula. If by month 4 the project has spent $420,000 on 38% of the work, the EVM metrics become:
- AC = $420,000
- EV = 38% × $990,000 = $376,200
- CPI = $376,200 / $420,000 = 0.896 (over budget)
- EAC = $990,000 / 0.896 = $1,104,911 (projected overrun of $114,911)
What BAC Does NOT Include
Key Rule: BAC = Cost Baseline = Direct Costs + Indirect Costs + Contingency Reserve.
BAC does not include Management Reserve (held by management for unknown-unknown risks).
BAC + Management Reserve = Total Project Budget.Why BAC Must Never Change Mid-Project
A cost overrun does NOT change BAC. If your project overspends, you track this through:
- CV (Cost Variance) = EV − AC → shows current overrun amount
- EAC → shows revised total cost forecast
- VAC (Variance at Completion) = BAC − EAC → shows projected final overrun
If the project scope formally changes (approved change request), only then can the BAC be re-baselined. This is called a budget revision and requires formal change control.
→ Build Your BAC with Our Free Calculator ,104,911 (prognozētaisBudget at Completion Formula (BAC Formula)
The Budget at Completion (BAC) formula is the foundation of Earned Value Management. It defines the total approved budget for all project work. Per PMBOK 6th Edition (p.263), the BAC formula is:
BAC = Sum of all budgets established for the work to be performedIn plain terms: every work package, cost category, and contingency reserve is estimated and summed. The total is your BAC. Once approved at baseline, it is fixed — BAC does not change when costs overrun. Only the Estimate at Completion (EAC) changes.
BAC Formula in Context of EVM
The Budget at Completion formula feeds directly into every other EVM metric:
Metric Uses BAC? Formula Planned Value (PV) ✓ % Planned × BAC Earned Value (EV) ✓ % Complete × BAC CPI Indirectly EV / AC EAC (typical) ✓ BAC / CPI VAC ✓ BAC − EAC TCPI ✓ (BAC − EV) / (BAC − AC) An inaccurate BAC makes every downstream EVM metric unreliable. Getting the BAC formula right is the most important step in project cost management.
5 Methods to Calculate BAC
There is no single algorithm for building BAC. PMBOK defines several estimation approaches, each suited to a different level of project definition:
1. Bottom-Up Estimation (Most Accurate)
BAC = Σ (cost of each work package)Estimate every individual work package, then sum all estimates. Accuracy: ±5–10%. Requires detailed scope definition. This is the approach used in our BAC Builder tab.
2. Analogous Estimation
BAC = Actual cost of similar past project × adjustment factorUse data from a comparable completed project as the starting point. Accuracy: ±25–75%. Fast but relies on having relevant historical data. Best for early-stage budgets.
3. Parametric Estimation
BAC = unit cost × quantity (e.g. $/m² × project area)Derive cost from a statistical relationship between project scope and unit cost. Accuracy: ±10–20%. Common in construction (cost/m²), software ($cost/function point), and manufacturing.
4. Three-Point Estimation (PERT)
BAC = (Optimistic + 4 × Most Likely + Pessimistic) / 6Weight three scenarios to produce a probability-weighted estimate. PERT accounts for schedule and cost uncertainty, making it more reliable than a single-point estimate.
5. Expert Judgement
Consult qualified subject matter experts when no comparable data exists. Combined with any of the above methods. Accuracy depends entirely on expert experience.
Worked Example: Applying the BAC Formula
A company is planning an office renovation project. The project manager applies bottom-up estimation to each work package:
Work Package Budget Demolition & Site Prep $80,000 Structural Work $220,000 Electrical & Plumbing $180,000 Interior Fit-Out $340,000 Project Management $80,000 Contingency Reserve (10%) $90,000 BAC (Cost Baseline) $990,000 Management Reserve (5%) $50,000 Total Project Budget $1,040,000 This is the BAC: $990,000. The management reserve ($50,000) is held separately and is NOT part of the BAC formula. If by month 4 the project has spent $420,000 on 38% of the work, the EVM metrics become:
- AC = $420,000
- EV = 38% × $990,000 = $376,200
- CPI = $376,200 / $420,000 = 0.896 (over budget)
- EAC = $990,000 / 0.896 = $1,104,911 (projected overrun of $114,911)
What BAC Does NOT Include
Key Rule: BAC = Cost Baseline = Direct Costs + Indirect Costs + Contingency Reserve.
BAC does not include Management Reserve (held by management for unknown-unknown risks).
BAC + Management Reserve = Total Project Budget.Why BAC Must Never Change Mid-Project
A cost overrun does NOT change BAC. If your project overspends, you track this through:
- CV (Cost Variance) = EV − AC → shows current overrun amount
- EAC → shows revised total cost forecast
- VAC (Variance at Completion) = BAC − EAC → shows projected final overrun
If the project scope formally changes (approved change request), only then can the BAC be re-baselined. This is called a budget revision and requires formal change control.
→ Build Your BAC with Our Free Calculator 14,911 pārtēriņš)
Ko BAC NEIETVER
BAC neietver Vadības rezervi (ko vadība tur nezināmiem riskiem).
BAC + Vadības rezerve = Kopējais projekta budžets.
Kāpēc BAC nekad nedrīkst mainīties projekta vidū
Izmaksu pārtēriņš NEMAINĀ BAC. Ja jūsu projekts tērē pārāk daudz, jūs to izsekojat, izmantojot:
- CV (Izmaksu novirze) = EV − AC → parāda pašreizējo pārtēriņa apjomu
- EAC → parāda pārskatīto kopējo izmaksu prognozi
- VAC (Novirze pabeidzot) = BAC − EAC → parāda prognozēto galīgo pārtēriņu
Ja projekta apjoms formāli mainās (apstiprināts izmaiņu pieprasījums), tikai tad BAC var pārskatīt. To sauc par budžeta pārskatīšanu, un tam nepieciešama formāla izmaiņu kontrole.
→ Izveidojiet savu BAC, izmantojot mūsu bezmaksas kalkulatoru