How to Calculate Scuba Diving Allowance: Step-by-Step

Scuba diving allowance in one line

A scuba diving allowance is simple: a monthly base amount, plus the number of paid scuba diving sessions multiplied by the price of one scuba diving session, all multiplied by twelve for the year. Base plus scuba diving sessions times price, then times twelve. The worked example throughout is a $100.00 monthly base, 2 scuba diving sessions a month, and $75.00 per scuba diving session, which totals $250.00 a month and $3,000.00 a year. That one line is the whole method; everything that follows is about getting the three inputs right, because a wrong input repeats itself twelve times in the year total.

Step 1: Price the monthly base allowance

The base allowance is the flat amount set each month for scuba diving extras, before any paid scuba diving sessions. Regulator servicing set aside monthly, mask and fin upkeep, mouthpieces, defogger and small recurring extras belong here. A new tank or full gear set, a dive-club membership and travel do not: a membership paid yearly is a lump sum, tanks and gear sets are one-off purchases, and travel varies by session and by dive site. If your club or employer sets the base, use their figure exactly. If you set it yourself, look at last season: add up a typical month of regulator servicing, mask upkeep, mouthpieces, defogger and small extras, and use that monthly average. Check that your base is monthly before multiplying by twelve, because a yearly figure mistaken for a monthly one inflates the answer twelvefold.

Step 2: Count only the paid scuba diving sessions

Session-counting is the heart of this step: count the scuba diving sessions you pay for individually each month, and nothing else. Sessions covered by a dive-club membership or already included in the base allowance cost $0.00 extra, and counting them inflates the total by a full per-session price each time. A month with 2 paid sessions and 6 covered boat dives is a 2-session month for this calculation, not an 8-session month. If your schedule varies, use the average month across the season: 24 paid sessions over a 12-month year is 2 a month, even if one month held 4 and another held none. The average is what makes the year total honest.

Step 3: Add the lines and multiply by 12

Multiply the paid sessions by the per-session price — 2 × $75.00 = $150.00 — then add the base: $100.00 + $150.00 = $250.00 a month. Multiply by 12 for the year: $250.00 × 12 = $3,000.00, split as $1,200.00 of base ($100.00 × 12) and $1,800.00 of sessions ($150.00 × 12). Keep the two lines separate all the way through: the split is what lets you check the result, compare seasons, and see which line is driving the total. The base share here is $100.00 ÷ $250.00 = 40.00% of the month, and it rises whenever sessions fall, because the base stays fixed while the sessions line shrinks.

Step 4: Check the result backwards

Work backwards from the monthly total to prove each input. The base behind $250.00 a month is $250.00 − $150.00 = $100.00; move it to $90.00 and the month falls to $240.00, move it to $110.00 and the month rises to $260.00. The per-session price behind $250.00 a month is ($250.00 − $100.00) ÷ 2 = $75.00; at $65.00 the month is $230.00, at $85.00 it is $270.00. The sessions behind $250.00 a month are ($250.00 − $100.00) ÷ $75.00 = 2; at 1 session the month is $175.00, at 3 sessions it is $325.00. If any backward check lands somewhere you did not expect, the input behind it is the one to re-examine, and the check costs nothing but a minute.

A season in numbers

Scuba diving rarely runs flat across the year, so test the method on a short season before trusting the yearly figure. Take four months: a holiday month with 4 sessions, two ordinary months with 2 sessions each, and a winter month with 0 sessions. The months cost $400.00, $250.00, $250.00 and $100.00, which add to $1,000.00 over the four months — an average of $250.00 a month, exactly the worked example. That average is the honest input for the year total: pricing the holiday month as if it were every month would turn the season into $1,600.00 for those four months alone, while pricing the winter month as typical would understate it at $400.00. Seasons, not single months, are what the year total describes.

Common mistakes

The most common mistake is counting covered sessions as paid ones: a boat dive already inside the membership is not a $75.00 session, and adding it double-counts the membership. The second is putting one-off kit into the base: a new tank belongs in the month it is bought, not spread across every month of the year. The third is entering the busiest month as if it were every month: a 4-session holiday month priced as the average turns a $3,000.00 year into a $4,800.00 year on paper. The fourth is a per-session price that omits tank fills or guide fees: the boat fee alone is not the session cost when fills and a guide are also paid, and the missing amount repeats every session, so a $10.00 omission becomes $240.00 over a 24-session year.

Worked example, start to finish

Base $100.00, 2 scuba diving sessions, $75.00 per scuba diving session. Sessions line: 2 × $75.00 = $150.00. Monthly total: $100.00 + $150.00 = $250.00. Yearly total: $250.00 × 12 = $3,000.00 — $1,200.00 base plus $1,800.00 sessions. Check it backwards: $250.00 − $150.00 = $100.00 base, ($250.00 − $100.00) ÷ 2 = $75.00 per session, ($250.00 − $100.00) ÷ $75.00 = 2 sessions. Add a third session and the month becomes $325.00; drop to one session and it becomes $175.00. Raise the base to $120.00 and the month becomes $270.00, the year $3,240.00. The base share is $100.00 ÷ $250.00 = 40.00% of the month.

What changes the answer most

Sessions move this allowance more than anything else, because each one carries a full per-session price: a $10.00 change in the per-session price moves the month by $20.00, while the same $10.00 change in the base moves it by only $10.00. A miscounted session is a $75.00 monthly error, or $900.00 over the year. Check the sessions first when an allowance feels wrong, then the per-session price, and only then the base.

Frequently asked questions