Spreadsheet vs leave software: the breaking points at 10, 20, 30 employees
Most teams start leave tracking with a spreadsheet because it's free, familiar, and "seems simple enough." For 5-7 people, it often works fine. But as you grow, spreadsheets break in predictable ways: approval workflows become inconsistent, visibility lags behind reality, and manual errors compound.
This guide breaks down the specific breaking points at 10, 20, and 30 employees, backed by data on absence rates, spreadsheet error research, and practical checklists to help you decide when (and how) to upgrade.
TL;DR Answer
Spreadsheets can work for leave tracking at very small team sizes, but they break in predictable ways as you grow: approvals become inconsistent, visibility becomes unreliable, and errors creep in. At 10 employees you start feeling coordination friction, at 20 you see real delivery risk from overlapping leave, and at 30 the admin load and audit/compliance risk usually outweigh the cost of proper leave software.
Q: Why does leave tracking break as teams grow?
A: Scaling friction in leave tracking comes from five predictable patterns:
- More requests: 5 people = ~10 leave requests/year. 30 people = ~60 requests/year. Volume alone creates coordination overhead.
- More overlap: The probability that 2+ people want the same week off rises exponentially with team size.
- More roles/locations: Different roles have different cover requirements. Multiple locations mean multiple public holiday calendars.
- More policies: Part-time staff, contractors, different accrual rules — simple policies become complex.
- Higher delivery impact: Losing 1 person in a 5-person team is 20% capacity. In a 30-person team, it's 3.3% — but if that person is the only deployer or client contact, the impact is still 100%.
Simple capacity math:
- 10-person team: 1 person off = 10% capacity drop
- 20-person team: 1 person off = 5% capacity drop
- 30-person team: 1 person off = 3.3% capacity drop
But this is deceptive: if that one person is a critical role (only QA lead, only DevOps, only finance approver), the effective capacity drop is far higher. Leave visibility directly impacts delivery planning and resource allocation.
Q: What legal/compliance pressure makes tracking important (UK baseline)?
A: In the UK, tracking leave isn't optional — it's a legal requirement:
Holiday entitlement (GOV.UK):
According to GOV.UK guidance, "Most workers who work a 5-day week must receive at least 28 days' paid annual leave a year." This is a statutory minimum.
Record-keeping (ACAS):
ACAS guidance on working time rules states that "Employers must keep these records for 2 years..." covering daily working hours, weekly hours, and leave taken.
Practical implication: If an employee disputes their leave balance or HMRC audits your payroll, you need accurate records. A spreadsheet with manual edits, unclear approval trails, and version conflicts doesn't meet this standard. This is not legal advice — check your specific legal obligations and employment contracts — but the compliance baseline is clear: accurate records, retained for 2+ years, with approval trails.
Q: What does real-world 'unplanned absence' look like in numbers?
A: Even with perfect annual leave planning, you still need to account for unplanned absence. According to the ONS Sickness Absence in the Labour Market report (2023 and 2024):
- 2.0% of working hours were lost to sickness absence in 2024
- 148.9 million working days were lost across the UK
- The average worker took 4.4 days off sick per year
Why this matters: Your 20-person team will lose approximately 88 days to sickness absence per year (20 × 4.4 days). That's nearly 18 weeks of cumulative capacity. If your leave tracking only shows planned annual leave, you're missing a huge piece of the capacity planning puzzle. Teams that track only annual leave get surprised by sick leave patterns — but those patterns are predictable at population level.
Q: Why spreadsheets fail (it's not Excel — it's operational risk)
A: Spreadsheets aren't inherently bad. The problem is operational risk: errors, version control, and audit trails.
Spreadsheet error research: According to Raymond R. Panko's comprehensive research on spreadsheet errors, studies of audited spreadsheets consistently find that 88% or more contain errors. The Dartmouth literature review on spreadsheet errors documents decades of similar findings across industries.
Operational consequences: The European Spreadsheet Risks Interest Group (EUSPRIG) maintains a collection of real-world spreadsheet error stories — many involving payroll, financial reporting, and compliance failures. The common thread: manual processes, multiple contributors, and no automated validation.
Context switching cost: Leave tracking via spreadsheet also has a hidden cost. According to Gallup research on workplace interruptions, workers take an average of 23 minutes and 15 seconds to resume work after an interruption. Manual leave approval via email/spreadsheet creates constant context switches for managers.
The fair argument: Spreadsheets are fine until the cost of mistakes (wrong balances, missed overlaps, compliance gaps) plus admin time (chasing updates, reconciling versions) exceeds the cost of proper software. For most teams, that inflection point is between 10 and 20 employees.
Q: Breaking points by team size (10 vs 20 vs 30)
A: Leave tracking breaks in predictable stages. Here's what typically fails first:
| Team size | What breaks first | Symptoms | Risk level | What to do next |
|---|---|---|---|---|
| ~10 employees | Version control & visibility | "Which sheet is right?"; approvals via email/Slack; people forget to update | Low-Medium | Lock sheet, single owner, form intake, sync to calendar |
| ~20 employees | Overlapping leave & delivery risk | 2+ people off same week monthly; critical skills gaps; public holiday confusion (multi-location) | Medium-High | Weekly team calendar review, cover planning, consider software with approval workflow |
| ~30 employees | Audit trail, reporting & admin load | Can't prove approvals; disputes increase; utilisation reports manual/slow; admin spends 5+ hrs/week on leave tracking | High | Move to dedicated leave software; software cost < admin time cost |
Q: Comparison table — spreadsheet vs calendar vs leave software
A: You need one source of truth for leave. Here's how the main approaches compare:
| Approach | Visibility | Approval workflow | Audit trail | Error risk | Best for |
|---|---|---|---|---|---|
| Spreadsheet | Manual, lag | Email/Slack (off-system) | None or weak | High (88%+ error rate) | Teams under 10, infrequent requests |
| Shared calendar | Good (real-time) | Email/Slack (off-system) | None | Medium (no balance tracking) | Visibility only; no compliance needs |
| Leave software | Excellent (real-time) | Built-in (request→approve→track) | Complete (who/what/when) | Low (validation, no manual calc) | Teams 10+; compliance; overlaps |
Key insight: A shared calendar solves visibility but not approval workflow, balance tracking, or audit trail. A spreadsheet tries to do everything but lacks real-time sync and validation. Dedicated leave management software is the only approach that handles all four dimensions well.
Q: The "Breaking Points Checklist" (when to upgrade)
A: Run this checklist weekly (for teams 10-20) or quarterly (for teams under 10) to catch breaking points early:
📋 Breaking Points Checklist
- Count monthly leave requests and approval paths
How many requests happen "offline" (email, Slack, verbal) vs in your system? If >20% are outside the spreadsheet, you have a visibility problem. - Check overlap frequency
Count weeks where 2+ people in the same team are off simultaneously. If this happens monthly and causes delivery issues, you need better planning visibility. - Check "time-to-approve" and "time-to-update"
Measure how long requests sit unapproved and how long it takes to update the sheet. Lag >48 hours creates planning surprises. - Check single points of failure
Identify roles where only one person has critical skills (only deployer, only payroll/finance approver, only client contact). If they're off and nobody knew in advance, you have a coverage planning problem. - Validate balances (carry-over, accrual, part-time)
Audit a random sample of 5-10 employee balances. Spot inconsistencies (carry-over errors, wrong accrual calculations) indicate manual calculation errors. - Check record-keeping readiness
Can you produce approval records and leave history if asked by HMRC or in a dispute? If not, you have a compliance risk. - Decide: stay on spreadsheet with fixes OR move to software
If you have 2+ upgrade triggers (see below), define success metrics (time saved, disputes reduced, overlaps caught) and budget for proper software.
Upgrade triggers (2+ means it's time):
- 2+ leave-related disputes per quarter
- 3+ overlap incidents per month causing delivery issues
- >20% of requests approved outside your system
- Admin spends 5+ hours per week on leave tracking
- Balance errors found in >10% of employee records
- Can't produce audit trail when requested
Q: Failure points & fixes (if you must stay on a spreadsheet)
A: If you're not ready to move to software yet, here are pragmatic mitigation steps. These buy you 6-12 months but don't solve the long-term scaling issues:
| Failure point | Why it happens | Fix this week |
|---|---|---|
| Version conflicts | Multiple people edit simultaneously | Lock sheet; single owner updates; use Google Form for intake |
| Approval lag | Requests via email, nobody updates sheet | Require all requests via form; auto-notify manager; set 48hr SLA |
| Balance errors | Manual formulas, copy-paste mistakes | Add validation checks; audit 10% of records monthly |
| Visibility lag | Sheet updated days after approval | Sync to shared calendar daily (or use Zapier/script) |
| Overlap surprises | No forward planning view | Weekly team review meeting; flag 2-4 week ahead overlaps |
| No audit trail | Approvals via email, not logged | Add "Approved by" + "Date" columns; require email screenshot |
| Inconsistent categories | People invent their own leave types | Standardize: Annual, Sick, Unpaid, Compassionate, Parental |
Q: Before vs after — what changes when you move to leave software?
A: The shift from spreadsheet to dedicated software creates measurable operational improvements:
| Scenario | Before (spreadsheet) | After (leave software) |
|---|---|---|
| Approvals tracked | Email/Slack (no central record) | Full audit trail (who approved, when, notes) |
| Calendar visibility | Manual sync (lags 2-7 days) | Real-time team calendar (same day) |
| Disputes | "My balance is wrong" (can't verify) | "Here's your history + calculations" (transparent) |
| Planning speed | Check sheet manually, 10-15 min per week | Dashboard view, 2-3 min per week |
| Reporting | Manual pivot tables, prone to errors | Automated utilisation/absence reports |
| Audit readiness | Hunt through emails + versions | Export full history in minutes (HMRC-ready) |
Bottom line: Teams moving from spreadsheets to leave software report 60-80% reduction in admin time, 3-5x faster approval cycles, and near-elimination of balance disputes.
Q: A data-backed PR angle (credible, not salesy)
A: If you want to share lessons learned or improvements in your leave tracking (team updates, blog posts, internal comms), here are credible stats:
- Absence baseline: UK workers lost 2.0% of working hours to sickness in 2024 (148.9m days; 4.4 days per worker average) — ONS
- Record-keeping requirement: UK employers must keep leave records for 2 years minimum — ACAS
- Spreadsheet error rate: Studies consistently find 88%+ of audited spreadsheets contain errors — Panko research / Dartmouth review
"Most teams outgrow leave spreadsheets between 10 and 20 employees — not because spreadsheets are bad, but because the operational cost (admin time + error risk + compliance gaps) exceeds the cost of proper software."
FAQ
Is a spreadsheet OK for leave tracking under 10 employees?
Yes, if leave requests are infrequent (2-3 per month) and your team works mostly in one location with simple policies. Once you hit 5+ requests per month or have overlapping leave causing delivery issues, consider upgrading.
What breaks first at around 10 employees?
Version control and visibility. Multiple people need to access the sheet, approvals happen over email/Slack, and the "which version is right?" question appears weekly. Approval workflows also become inconsistent.
Why does overlap become a real delivery risk around 20 employees?
At 20 people you typically have 2-3 small teams. When 2+ people from the same team take leave the same week (happens monthly), you lose critical skills and delivery slips. Without forward visibility, you catch this too late to adjust.
What changes at 30 employees that makes software worth it?
Audit trail, reporting, and admin load. You need to prove approvals for compliance, run utilisation reports for planning, ensure multi-team consistency, and the time spent chasing updates and fixing errors exceeds the cost of software.
What's the simplest fix if we stay on spreadsheets for now?
Single owner, sheet lock with form intake, weekly review meeting, and sync to a shared calendar. This buys you 6-12 months but requires discipline. Still no audit trail or automated approval workflow.
What should we look for in leave software?
Request/approval workflow, team calendar view, balance tracking with accruals, manager visibility, audit trail (who approved what when), and integration with payroll or HR systems if needed. Flat-fee pricing helps with budget predictability.
A simple option if you want leave + approvals + visibility without per-seat pricing
If you want leave management with request/approval workflow, team calendar visibility, balance tracking, and audit trails — without per-seat pricing — Zotrack offers flat-fee pricing that doesn't change as your team grows. Built for teams at the 10-30 employee breaking point.
References
- GOV.UK: Holiday entitlement rights
- ACAS: Working time rules (including record-keeping requirements)
- ONS: Sickness absence in the labour market, 2023 and 2024
- Raymond R. Panko: What We Know About Spreadsheet Errors (PDF)
- Dartmouth: Spreadsheet Errors Literature Review (PDF)
- EUSPRIG: Spreadsheet Error Horror Stories (operational risk examples)
- Gallup: Too Many Interruptions at Work? (context switching cost)