function calcSmallHall() {
  var hallType = document.getElementById('smallHallType').value;
  var timeSlot = document.getElementById('smallTimeSlot').value;
  var dayType  = document.getElementById('smallDayType').value;
  var aircon   = document.getElementById('smallAircon').value;
  var profit   = Number(document.getElementById('smallProfit').value);
  var advance  = document.getElementById('smallAdvance').value;
  var extend   = document.getElementById('smallExtend').value;

  // 小ホール（本番）
  var feeSmallMain = {
    morning: 9000, afternoon: 12000, night: 13500,
    daytime: 18000, day_night: 25500, allday: 30000
  };

  // 小ホール（準備）
  var feeSmallPrep = {
    morning: 4500, afternoon: 6000, night: 6750,
    daytime: 9000, day_night: 12750, allday: 15000
  };

  // 使用時間
  var hours = {
    morning: 3, afternoon: 4, night: 4,
    daytime: 8, day_night: 9, allday: 13
  };

  // 基本料金
  var base = 0;
  if (hallType === 'small_main') base = feeSmallMain[timeSlot];
  if (hallType === 'small_prep') base = feeSmallPrep[timeSlot];

  // 土日祝 2割増
  var addHoliday = (dayType === 'holiday') ? Math.round(base * 0.2) : 0;

  // 空調 5割増
  var addAircon = (aircon === 'yes') ? Math.round(base * 0.5) : 0;

  // 小計
  var fee4 = base + addHoliday + addAircon;

  // 営利割増（基本料金から算出）
  var addProfit = Math.round(base * profit);

  // 繰上・延長
  var count = 0;
  if (advance === 'yes') count++;
  if (extend === 'yes') count++;

  var finalFee = fee4 + addProfit;

  if (count > 0) {
    var extra = Math.floor((fee4 / hours[timeSlot]) * 1.3 * count);
    finalFee += extra;
  }

  // ★ 最終結果だけ一の位切り捨て
  finalFee = Math.floor(finalFee / 10) * 10;

  document.getElementById('smallHallResult').innerText = finalFee.toLocaleString();
}