Guide · Worked examples · Updated 20 September 2026

Night shift allowance: four examples you can check on paper

This page is the long-form arithmetic behind the Nights tab. Every row uses the same two rules the toolkit uses. It is not your company’s policy. If HR pays a published slab, skip the percentage model entirely.

Rule A (estimated %): per night ≈ (annual CTC ÷ working days) × allowance %. Default working days in the tool: 240. Default %: 25% (a midpoint of the 20–30% range people quote in Indian software conversations).

Rule B (fixed ₹): per night = the rupee amount on the offer letter or HRMS. Month = per night × nights rostered.

Yearly column in the calculator is “if this month repeated twelve times,” not a tax year forecast.

Example 1 — ₹12 lakh CTC, 25%, 18 nights

Daily CTC = 12,00,000 ÷ 240 = ₹5,000. Night slice at 25% = ₹1,250. Eighteen nights = ₹22,500 this month. If that pattern held all year, 22,500 × 12 = ₹2,70,000 extra before tax, attendance, and whether NSA sits inside CTC.

Step	Working	Result
Daily CTC	12,00,000 / 240	₹5,000
Per night	5,000 × 0.25	₹1,250
This month	1,250 × 18	₹22,500
If month repeats	22,500 × 12	₹2,70,000

That is the sample the homepage “Try a sample” button fills. It does not save to Remember unless you later Calculate with Remember ticked.

Example 2 — ₹8 lakh CTC, 20%, 22 nights

Some letters sit at the low end of the percentage band. Daily = 8,00,000 ÷ 240 ≈ ₹3,333.33. Twenty percent = ₹666.67 per night. Twenty-two nights ≈ ₹14,667.

Step	Working	Result
Daily CTC	8,00,000 / 240	₹3,333.33
Per night	3,333.33 × 0.20	₹666.67
This month	666.67 × 22	₹14,667

Example 3 — ₹18 lakh CTC, 260 working days, 25%, 12 nights

If your calendar is closer to 260 paid working days, daily CTC falls. Daily = 18,00,000 ÷ 260 ≈ ₹6,923.08. At 25% that is ₹1,730.77 a night. Twelve nights ≈ ₹20,769. Using 240 days instead would overstate the night rate. Always match working days to how HR defines them, not to a blog default.

Example 4 — Fixed ₹800 a night, 20 nights

Some software employers skip the percentage and publish a slab. If the letter says ₹800 a night: 800 × 20 = ₹16,000. Weekend or on-call rates are a second line — the free calculator uses one rate. Do not multiply ₹800 by 25% “just in case.”

What usually makes the payslip disagree

NSA already baked into CTC, so “extra” on the tool is not extra in bank.
Eligibility only if the shift starts after a clock time (often 10 pm).
Proration for unpaid leave, OD, or a half-month join.
PF or professional tax on the component.
A different day-count (22 per month, 26, or 365).

When the tool and the slip disagree, the slip (and the policy PDF) win. Use these examples to know whether a month is closer to ₹4,000 or ₹40,000 before you plan rent or a SIP.

Hike and tax sit on a different tab

Allowance is one cashflow. A 12% CTC hike is another. New versus old regime is a third. Mixing them in one cell is how people misread a letter. Run Nights, then Hike, then In-hand on the new CTC if you are signing. See whether 12% is typical and new vs old regime.