Hotel Attrition Calculator for Group Room Blocks
Group Hotel Attrition: Calculate Minimums, Shortfall, and Damages
Estimate attrition risk and damages before you sign. Upload your nightly grid or enter totals to model cumulative or per-night minimums, allowed attrition, resell credits, and final penalties.
Planning a group stay is easier when the math is clear. This Attrition Calculator turns contract terms into simple numbers you can use and understand; showing minimum performance, allowable drop, shortfall, and estimated damages in seconds.
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Attrition Calculator
Estimate minimum performance, allowable drop, shortfall, and damages for group room blocks. Choose Simple for a single ADR and total room nights, or Advanced to load a nightly grid and pick the calculation method.
Simple Advanced
Contracted room nights (total)
Allowed attrition %
Pickup (actual or forecast)
ADR used for damages
Damages % of rate
Resell credit (rooms)
Calculate Reset Simple method uses cumulative minimums.
Minimum performance—
Allowable drop—
Shortfall (rooms)—
Damages—
Inputs recap—
NotesFigures are estimates. Always follow the contract language for method and basis, and apply any wash/cutoff provisions first.
Allowed attrition %
Damages % of rate
Resell credit (rooms)
Method Cumulative
Per-night
CSV upload (optional) Columns: label/date, contracted, pickup, rate
Label / Date Contracted Pickup ADR Actions Add row Clear all
Calculate Reset
Minimum performance—
Allowable drop—
Shortfall (rooms)—
Damages—
Summary—
NotesCumulative compares totals across nights. Per-night applies nightly minimums and sums shortfalls. Resell credit subtracts rooms from shortfall, capped at the shortfall.
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// SIMPLE window.AC_computeSimple = function(){ const B = Math.max(0, parseFloat($("s_block").value)||0); const a = Math.max(0, parseFloat($("s_attrition").value)||0) / 100; const P = Math.max(0, parseFloat($("s_pickup").value)||0); const r = Math.max(0, parseFloat($("s_adr").value)||0); const d = Math.max(0, Math.min(100, parseFloat($("s_damages_pct").value)||0)) / 100; const R = Math.max(0, parseFloat($("s_resell").value)||0);
const M = B * (1 - a); // minimum performance const allowable = B - M; // allowable drop const S0 = Math.max(0, M - P); // shortfall before resell const S = Math.max(0, S0 - R); // billable shortfall after resell const damages = S * r * d;
$("s_min_out").textContent = Math.round(M).toLocaleString(); $("s_allow_out").textContent = Math.round(allowable).toLocaleString(); $("s_short_out").textContent = Math.round(S).toLocaleString(); $("s_damages_out").textContent = money(damages); $("s_breakdown").textContent = `Shortfall ${Math.round(S)} × ADR ${money(r)} × ${Math.round(d*100)}% damages`; $("s_recap").textContent = `Block ${Math.round(B)}, Attrition ${Math.round(a*100)}%, Pickup ${Math.round(P)}, Resell ${Math.round(R)}`; };
window.AC_resetSimple = function(){ $("s_block").value = 200; $("s_attrition").value = 20; $("s_pickup").value = 150; $("s_adr").value = 179; $("s_damages_pct").value = 80; $("s_resell").value = 0; AC_computeSimple(); };
// ADVANCED GRID const tableBody = () => $("a_table").querySelector("tbody");
function rowTemplate(label="Night 1", contracted=80, pickup=70, rate=179){ const tr = document.createElement("tr"); tr.innerHTML = ` Duplicate Remove
`; const [dupBtn, remBtn] = tr.querySelectorAll("button"); dupBtn.onclick = () => { const vals = getRowValues(tr); const clone = rowTemplate(vals.label+" (copy)", vals.contracted, vals.pickup, vals.rate); tableBody().appendChild(clone); }; remBtn.onclick = () => { tr.remove(); }; return tr; }
function getRowValues(tr){ const tds = tr.querySelectorAll("td"); return { label: tds[0].querySelector("input").value.trim() || "Night", contracted: Math.max(0, parseFloat(tds[1].querySelector("input").value)||0), pickup: Math.max(0, parseFloat(tds[2].querySelector("input").value)||0), rate: Math.max(0, parseFloat(tds[3].querySelector("input").value)||0) }; }
function getGrid(){ const rows = []; tableBody().querySelectorAll("tr").forEach(tr => rows.push(getRowValues(tr))); return rows; }
window.AC_addRow = function(){ tableBody().appendChild(rowTemplate(`Night ${tableBody().children.length+1}`, 50, 40, 169)); }; window.AC_clearRows = function(){ tableBody().innerHTML = ""; };
// CSV: columns label/date,contracted,pickup,rate window.AC_loadCSV = function(evt){ const file = evt.target.files && evt.target.files[0]; if (!file) return; const reader = new FileReader(); reader.onload = (e) => { const text = e.target.result; const lines = text.split(/\r?\n/).filter(Boolean); if (lines.length h.trim().toLowerCase()); const col = (n) => headers.indexOf(n); const idxL = col("label") >= 0 ? col("label") : col("date"); const idxC = col("contracted"); const idxP = col("pickup"); const idxR = col("rate"); if (idxC x.trim()); if (!cells.length) continue; const label = idxL >= 0 ? cells[idxL] : `Night ${i}`; const contracted = parseFloat(cells[idxC]) || 0; const pickup = parseFloat(cells[idxP]) || 0; const rate = parseFloat(cells[idxR]) || 0; tableBody().appendChild(rowTemplate(label, contracted, pickup, rate)); } }; reader.readAsText(file); };
window.AC_computeAdvanced = function(){ const a = Math.max(0, parseFloat($("a_attrition").value)||0) / 100; const d = Math.max(0, Math.min(100, parseFloat($("a_damages_pct").value)||0)) / 100; const R = Math.max(0, parseFloat($("a_resell").value)||0); const method = document.querySelector('input[name="a_method"]:checked').value;
const rows = getGrid(); if (!rows.length){ alert("Add at least one row."); return; }
const B = rows.reduce((s,r)=>s + r.contracted, 0); const P = rows.reduce((s,r)=>s + r.pickup, 0); const avgRateWeighted = rows.reduce((s,r)=>s + (r.rate * r.contracted), 0) / Math.max(1, B);
let M = 0, allowable = 0, shortfall = 0, damages = 0, breakdown = "";
if (method === "cumulative"){ M = B * (1 - a); allowable = B - M; const S0 = Math.max(0, M - P); const S = Math.max(0, S0 - R); shortfall = S;
// Use weighted average rate for damages damages = S * avgRateWeighted * d; breakdown = `Shortfall ${Math.round(S)} × Avg ADR ${money(avgRateWeighted)} × ${Math.round(d*100)}%`; } else { // per-night let S_total = 0; let nightlyShortfalls = []; rows.forEach(r => { const Mi = r.contracted * (1 - a); const si = Math.max(0, Mi - r.pickup); S_total += si; nightlyShortfalls.push({ short: si, rate: r.rate }); });
// Apply resell credit to highest-rate nights first nightlyShortfalls.sort((x,y)=>y.rate - x.rate); let Rleft = R; let damagesSum = 0; nightlyShortfalls.forEach(n => { if (Rleft s + r.contracted*(1-a), 0); allowable = B - M; shortfall = Math.max(0, S_total - R); damages = damagesSum; breakdown = `Per-night: shortfall ${Math.round(S_total)} minus resell ${Math.round(R)} = ${Math.round(shortfall)} billable; damages at nightly ADR × ${Math.round(d*100)}%`; }
$("a_min_out").textContent = Math.round(M).toLocaleString(); $("a_allow_out").textContent = Math.round(allowable).toLocaleString(); $("a_short_out").textContent = Math.round(shortfall).toLocaleString(); $("a_damages_out").textContent = money(damages); $("a_breakdown").textContent = breakdown;
$("a_summary").textContent = `Block ${Math.round(B)}, Pickup ${Math.round(P)}, Attrition ${Math.round(a*100)}%, Damages ${Math.round(d*100)}%, Resell ${Math.round(R)}. Method: ${method === "cumulative" ? "Cumulative totals" : "Per-night minimums"}.`; };
window.AC_resetAdvanced = function(){ $("a_attrition").value = 20; $("a_damages_pct").value = 80; $("a_resell").value = 0; $("a_cum").checked = true; AC_clearRows(); // Seed a few example nights tableBody().appendChild(rowTemplate("Night 1", 80, 70, 179)); tableBody().appendChild(rowTemplate("Night 2", 70, 50, 179)); tableBody().appendChild(rowTemplate("Night 3", 50, 30, 179)); };
// Initialize AC_resetSimple(); AC_resetAdvanced(); })();
What is hotel attrition?
Hotel attrition is the difference between the rooms you contracted and the rooms your group actually uses. Most group contracts allow a certain percentage of “slippage” without penalty. If your pickup falls below the minimum performance after that allowance, the hotel can charge damages based on the contract terms.
Attrition protects the hotel’s expected revenue while giving your group some flexibility. Your agreement will spell out the allowed attrition percentage, the method used to measure performance, and how damages are calculated.
How is attrition calculated?
There are two common methods:
Cumulative: Compare total pickup to one minimum across the entire stay. Nights can offset each other.
Per night: Each night has its own minimum. Shortfalls on one night are not offset by another night.
Typical damages are a percentage of the room rate used for damages. Contracts usually use the group ADR or a stated base rate. Some agreements allow a resell credit, which reduces your shortfall by the number of rooms the hotel resold.
Key terms you will see in contracts
Allowed attrition %: The slippage you can use without penalty, for example 20%.
Method: Cumulative or per night.
Damages % and rate basis: The percentage to charge and which rate to use, for example 80% of group ADR.
Resell or mitigation: Credit for rooms the hotel resold, sometimes capped at the shortfall.
Cutoff and wash: Dates that allow you to reduce the block before penalties apply.
Taxes and fees: Whether taxes or resort fees are included in damages. Many contracts exclude taxes from damages.
Quick example
Contracted room nights: 200
Allowed attrition: 20% → minimum performance = 160
Pickup: 150 → shortfall before resell = 10
Resell credit: 0 → billable shortfall = 10
ADR used for damages: $179
Damages percent: 80%
Damages = 10 × $179 × 0.80 = $1,432
Planner tips
Confirm the method. Per night is stricter than cumulative.
Apply wash or cutoff reductions first, then measure attrition.
Ask how resell credit is documented.
Check if damages include or exclude taxes and fees.
If your pattern shifts, revisit the block by night. Small moves can protect the minimum.
The math (clean formulas you can implement manually)
Cumulative method (single ADR)
Contracted room nights = BBB
Allowed attrition % = aaa
Minimum performance = M=B×(1−a)M = B \times (1 - a)M=B×(1−a)
Actual (or forecast) pickup = PPP
Shortfall (before resell) = S0=max(0,M−P)S_0 = \max(0, M - P)S0=max(0,M−P)
Resell credit rooms = RRR (if allowed)
Billable shortfall = S=max(0,S0−R)S = \max(0, S_0 - R)S=max(0,S0−R)
Group ADR used for damages = rrr
Damages % = ddd (e.g., 0.80 for 80%)
Damages = S×r×dS \times r \times dS×r×d(Optionally multiply by tax if contract requires, but usually it doesn’t.)
Per-night method (rooms-by-night) For each night iii:
BiB_iBi = contracted rooms, PiP_iPi = pickup, rir_iri = rate
Minimum Mi=Bi×(1−a)M_i = B_i \times (1 - a)Mi=Bi×(1−a)
Shortfall si=max(0,Mi−Pi)s_i = \max(0, M_i - P_i)si=max(0,Mi−Pi)
Billable shortfall after resell credit per night (if defined that way): si′s_i'si′
Damages =∑isi′×ri×d= \sum_i s_i' \times r_i \times d=∑isi′×ri×d
Tiny worked example (cumulative):
Contracted B=200B=200B=200, allowed attrition a=20%⇒M=160a=20\% \Rightarrow M=160a=20%⇒M=160
Pickup P=150⇒S0=10P=150 \Rightarrow S_0=10P=150⇒S0=10
Resell credit R=0⇒S=10R=0 \Rightarrow S=10R=0⇒S=10
ADR r=$179r=\$179r=$179, damages % d=80%d=80\%d=80%
Damages =10×179×0.8=$1,432= 10 \times 179 \times 0.8 = \$1{,}432=10×179×0.8=$1,432 If the hotel resold 20 rooms and the contract credits resell, R=20⇒S=max(0,10−20)=0⇒$0R=20 \Rightarrow S=\max(0,10-20)=0 \Rightarrow \$0R=20⇒S=max(0,10−20)=0⇒$0 damages.
Per-night example (shows why method matters): Block by night = 80 / 70 / 50; with 20% attrition → minimums = 64 / 56 / 40 Pickup = 70 / 50 / 30 → shortfalls = 0 / 6 / 10 → 16 total shortfall Cumulative totals: block 200, min 160, pickup 150 → shortfall 10. So per-night can be stricter than cumulative.
